I didn't know his daughter passed. I been watching David's vids for about 6 months. I myself had extreme depression and anxiety and his voice and information I been putting on late at night. Its not the world us born before 1980 grew up in.. This man knows his stuff. No doubt
Funny you use the Ft/Lbs per C.I. instead of HP per C.I. I understand why you do it but, thru the modern day HP Torque equation and that equation's 5252 variable, HP and TQ are joined at the hip. I bought Vizards books back in the early 90's. It taught me to look at efficiencies or the lack thereof and how to qualify those efficiencies. First, the reasoning behind HP and Torque. The early engineers thinking of power and rotational force (torque), at a flywheel, was: The linear distance covered at the circumference of rotation is a product of the radius and angles covered. Therefor: linear distance = radius x angular distance Further: linear distance = linear speed x time Ergo: Power is, radius x angular speed x time Finally we can say: Torque = radius x force This can be transposed as: Force = torque ÷ radius = power Boring! Most ppl dont understand HP. Ppl thru the years have romantisized the HP variable into something its not. HP is a dimensionless unit. Not until you add Displacement and RPM via the use of Radians can HP be measured. TQ on the other hand can be measured; without any other variable. Prior to the 1870's TQ was known as the Moment of Force. The HP Tq equation was created to qualify TQ per minute per second; aka, RPM. I'll try to be quick here. Radians, regarding Circular Functions such as Rotational Frequency as applied to an engine's flywheel have 2pi for one rotion; 1 RPM. Half a rotation is 1pi or half a Radian. So, 3.14159 is 1pi, while 6.283 is 2pi.., 1Radian, or 360°. Keep that to the side for the moment. James Watt back in the late 1600's qualified HP with his 33,000 ft/lbs per minute equation or 550 HP per second. However, RPM was never qualified. To qualify HP we take Watt's equation one step further. Take the 2pi per rotation and divide it by 60 seconds. 6.283 ÷ 60 = .1047166 This number gives us Radians per second. Now divide Watt's 1/HP per second number by Radians per second. 550 ÷ .1047166 = 5252 There is your Time Qualifier for HP. In other words, how efficient or inefficient is TQ being utilized at any given RPM. You can also use the 33,000 number and divide by 6.283. 33,000 ÷ 6.283 = 5252 The 5252 variable is nothing more than a "Time" qualifier of Torque. By default once Torque is qualified into a Per Minute Per Second equation, you have also qualified or Time Stamped HP per minute per second for any given RPM. There's the skinny on the HP, TQ, RPM, and the 5252 equation. Some say HP doesnt exist. That is an incorrect conclusion. HP, without Displacement and RPM, doesnt exist is a correct conclusion --Edited for typo's--
@@kevinshasteen5682 said "James Watt back in the late 1600's qualified HP with his 33,000 ft/lbs per minute equation " ... I just want to add that Watt was selling a steam engine to replace horses that were lifting water out of mines with ropes and pulleys. An 8 Horse Power engine would do the work of 8 horses, including the resting horses and the ones walking backwards to re-set the bucket for the next load of water. An actual draft horse can make 16 Horsepower for a few minutes then needs a break. A Tour De France cyclist makes 2/3 Horsepower during the race, then there's the guy who pedaled the plane across the English Channel. Horsepower is a really handy way of comparing cars and motorcycles.
@@peterdarr383 I used to ride a mountain bike long distance for exercise. Furthest I ever went was 55 miles; nothing like the Tour De France guys - those guys are in a league all their own. One interesting tid bit on James Watt. In his days, late 1600's to early 1700's, it was a bragging right to obtain a patten/copyright from the King or an Engineering Guild, also regulated by the king, for any new idea to help distribute your product. Even though James Watt never qualified Torque Per Minute Per Second (per RPM), James Watt had created a Pressure Wave signature for his Steam Engine Cylinder he built but never applied for copyright/patton on his Pressure Wavw tech; and kept it secret, hence his reputation for always being able to build a more efficient engine than others. It took the engine building world another 100 years to catch up to his Pressure Wave graphing technology. Must've been amazing times in the early days of Engine Modeling.
@@kevinshasteen5682 Actually, can you answer some questions for me? 1. Why do HP and TQ appear as two separate lines on a dynamometer if they are derived from one another? Asked another way: why do people measure both variables if they are part of the same equation? Couldn't/shouldn't we just be measuring power with one line and call it a day? 2. If TQ and HP are so intricately related (which I believe they are), how is it that Torque can drop off so rapidly, but HP continues to rise through the RPM range? And why does HP normally start to take off right around the time TQ drops? I haven't done the math, but the increased RPM doesn't seem like it would make up the difference. 3. I like your explanation that HP is a measure of how efficiently torque is being applied at a given RPM. What affects the ability of the torque to be applied? If it's an engine-only dyno (not a rear-wheel dyno), it can't be the transmission, driveshaft, rear differential, or wheels. What parts/processes in the engine make the torque be applied more efficiently at some RPM and less efficiently at others? 4. How the hell does a dyno measure Torque? I've always wondered that. Is it just that the spinning drum can tell how much force is being applied to it (if it's that kind of dyno) and can somehow calculate TQ and also differentiate it from Horsepower?
I found David in recent months,what a wealth of knowledge,ive rebuilt a bunch of engines but just went by factory specs of cams etc.Then I watch his variable adjustable cam drive and cams need to talk /match heads and on and on.
Dear Mr. David Vizard. I love your books and mow THIS! This is really cool. One suggestion, maybe consider using a wireless microphone on your collar. If you don’t take my suggestion I will still watch everything you put on your channel. You’re one of my personal heroes. Keep up the good work.
I watch your channel most every night. I just subscribed per your request. Have read several of your books over the years and they are second to none for the info I seek. Thanx so much sir and carry on.
Thank you David for many years of dedicated information sharing. I followed as a kid ‘Gods Manual ‘ to the series A and managed to make my Mild road build clubman 1275 ‘feel like a 1380 to the Dyno man . Never seen your videos until Richard Holdener mentioned you in one of his. Hope you carry on for many more years !!
He’s one of the best to give you the information without all the hoopla. A truly good man with vast knowledge on the engineering of a motor for the job.
Thanks very much, I have your porting book and how to make big power on a budget BBC and your Holley carb tuning book , I have leaned loads of information and love them .
Hey david. Love the research you have done, and always enjoy learning new things from your books and videos. You and the late Bill Metzner (lazer cams) have taught me a lot, especially on lsa. You guys are the only ones who are on the other side of the LSA spectrum , from the cam companies. I built a 406 sbc with 11.5-1 comp and a mech flat tappet on a 104 (custom) LSA. My boys thought I was nuts!. But it ran way better than expected, and they had a blast with it. Thank You!
Mr. Vizard, I thoroughly enjoy watching your videos and that you share your experience and expertise with us. I have learned a great deal from you. Long story short… I experienced what a bowl port and port matching can do as a teen. I have been an enthusiast ever since. I am watching your naturally aspirated vs boosted/nitrous discussion now. I value your opinions. Keep it up and God Speed!
i would love to know how to take advantage of long con rod ratios and ir intakes . all of the local speed shops race car specialist in my area think i am backwards or nuts, ive read most of your books they are very good well worth the money. thank you for your amazing knowledge .
CBob's Country Bunker his books state that properly tuned IR intakes are the best, but incredibly expensive. Within the parameters of a production block, con rod ratios aren't worth too much power. Bad ratios are worse with lower compression engines, as high compression does most work towards the top of the downstroke, minimizing side-loading.
what engine? i'll help. i'll give you my calculus blueprint of engine and you double check it or use it or get some one to compare theirs. what kind of engine do you want? chevy , ford , mopar? other? number of cylinders.
@port nut yeah in the end, stuffing as many cubic inches in to the block will get the most power, even with the additional piston wall friction. As RPM rises, frictional losses increase exponentially. So, for a street motor, with about 10.5:1 compression, and a Max room of about 6,500, don't even worry about rod length.
@port nut that said, long rods increase tdc dwell, allowing the charge mixture more time to enter the cylinder. Potential "5th stroke" power is improved. (That's the ability of the tuned exhaust to create a negative pulse during overlap. Get that timing right, and you have effectively "super-charged" the cylinder with more air than the volume of the cylinder should hold.) That's the pro-stock way. Like greater than 115% efficiency.
The "width" of the torque curve & where torque is made are also important. The lower the rpm & longer the engine builds good torque, the more useable it will be on the street. You can build a 302 with about 10:1 compression, flat juice cam, ported OE big chamber heads, & a dual plane intake that will build more mid range torque than a 460.
i have used all your books on small block mopar and were very helpful helped me to win many street races. wish you would get into the gen 3 hemi and see what you can do
yeah chevy 355 street builds getting 380 tq, less than the 400tq of a 302 ford is the common build. and 350 sbc that get 400 tq and 415 hp round abouts still a far cry of the 400tq and greater hp of the 302 on a thought out attention to detail build like david vizard'S builds and studies. What a great science it is, engine building.
Theoretical CR in a motor is related to cam events so wouldn't it be OK to use actual cranking pressure to be able to use a higher theoretical CR? I've been using the same (cheap) compression tester for about 30 yrs using a max cranking pressure of 220lbs/in2 with good results. The theoretical CR is usually around 13~15:1, BUT, it's on air-cooled motorcycle engines with probably easier/better heat transfer with small combustion chambers
Hello my friend I just wanted to start thanking you for all the correct information on all your videos, I have a 2010 grand cherokee wk1 srt8 6.1 hemi and recently got a bad lifter lifter so now I'm in the process of swapping a better performance camshaft on my stock 6.1L hemi 370 CI with a 10.2 to 1 compression ratio with 2.08'' intake valve diameter & 1.60'' exhaust valve diameter and has been searching online for the specs of my stock cam ( with no luck ) to be able to compare it to the many different aftermarket options out there so I can make the right decision on what camshaft/springs etc to go with on the stock torque converter in order to get the most physically possible torque/power out of my engine which I'll use on the streets every day so PLEASEEEE if you don't mind and can provide me the specs/manufacturer for the correct camshaft I need it'll be greatly appreciated, THANKS IN ADVANCE
Hey: Tony Robbins can't wrap his head around physics. I'm ok leaving this content to the real pros. But youtube has rescued you with one little trick: use their 1.25x speed setting, and it presents better with the quicker pace. Problem solved.
Flinch, thank you, I would’ve never thought of that. Dave S. Not so much. I agree. David Vizard is has great knowledge, but is hard to listen to. I think it would help if he used a microphone on his collar. God bless UA-cam.
I GOT A 1990 K5 BLAZER 5.7 WITH ECU GOT ENGINE REBUILD GOT THE BLOCK BORED 30 OVER AND DID A FEW UP GRADES IM USING EX262H CAM IN IT WHAT WOULD BE A GOOD COVERTER TO USE I TOOK THE STOCK ONE OUT..AND GOT 2000 TO 2400 STALL .. IS THAT GOOD WITH THAT CAM
*Part 1* You're right in a lot of senses but HP is a misleading component to the uninitiated. As to some extent the crossover point (of Torque and HP) is merely a function of what, years ago, one person (Mr. Watt) roughly assumed the work a horse could do; in order to normalize predictions/calculations related to horse and work requirements. After all, there is no one ideal horse that is identical to all others, for all years. Many other variables also exist. You can't have HP without torque. Your view (or at least what I understand it be) is correct; in that Torque is force over a distance and HP a product/derivative of it. However, I find it easier to consider Torque as a force associated with objects that spin and/or rotate - it is simply another force, albeit an angular one/force. HP is also a force - a force that is (derived from Torque and) usually associated with objects that move in a straight or linear path. To a great extent HP (within the car industry) only exists because yesteryear’s engineers and mechanics were befuddled about why internal combustion engines continued to generate higher peak force/thrust numbers at times when the BPEP of the engine was falling most due to poor cylinder filling. It is correct to assume that the car with the greater HP figure will (at some point {provided both cars have the same weight and aerodynamic drag} usually win the race) enable the car it is fitted to to experience the greatest forward force/thrust - but usually that’s only for that limited amount of time when the car with the greater Torque (but lower HP) maintains complete Torque (cylinder filling). So long as that happens forward thrust will usually to be greater than that produced by, say, another competitor car with less Torque and less peak crankshaft rotational speeds; and this is so because the engine/car will accelerate faster due to the faster engines speeds made available by way of the accumulation rising rate of the crankshafts rotational speeds (even though the cylinders are not completely filling and torque may be compromised). This is one reason why electric cars with less maximum HP than internal combustion engine vehicles often beat them off the mark and sometime across the entire ¼ mile. Their Torque(and HP) are either consistently higher for a longer period of time than most internal combustion engines, or the internal combustion engine has a lower Torque specification. Same for a lot of diesel engines out there that produce significant Torque figures and relatively low HP figures. If these engines were to produce their max/high Torque output at really low RPM (as most do) and also maintain that for a few thousand revs (as most do), then usually they will deliver - to the tail-shaft force and/or thrust - greater numbers and cylinder filling that will allow the electric vehicle within which that harnesses it, to beat a typical gasoline engine that must climb to its rev ceiling to access the peak HP. It may sound like I am splitting hairs here, but it is these nuances that confuse people about Torque and HP; as some people can't understand why one car does not beat another (with an equivalent engine, mass, ect) when/if the losing car has greater torque. A good understudy (and video opportunity ) as to how Torque offsets HP and vice versa, is how the La Ferrari, McLaren and Porsche Spyder perform in a ¼ mile drag race. They all have differing Torque shaping systems of either the electric or manifold compression sorts, or both; and it is interesting to note how all the trade offs - in internal combustion engine and electric motor power/Torque, and overall weight, turbocharger lag, and peak available current to the electric motors - play out. Another good understudy as to how Torque offsets HP and vice versa is within Audi’s range of turbocharged 6 and 8 cylinder offerings (with high Torque figures in low RPM) compared to the naturally aspirated (but high HP) Audi R8. -Torque-: I find it easy to explain Torque (for an internal combustion engine) as the peak pressure (or force resulting from combustion and/or BMEP) in the cylinders at any 1 point in time. This is (loosely) the BMEP approach to explaining Torque. Peak Torque of an old steam engine is at peak pressure; and that holds within reason to be the same for the internal combustion engine. When the pressure between the cylinders and head is at peak pressure or peak BMEP, this is where the maximum Torque is. Obviously there are differences; but there are also a lot of similarities. Jim Stanley. EX AMG Powertrain Engineer. Electronic/Electrical Engineer. PhD Electroacoustics
Part 2 Anyway, (and here is the kicker) as the engine’s crankshaft (a rotational object) speeds increase there is less and less time for effective/complete cylinder filling, so naturally this limitation on gas exchange will dictate a lower peak pressure (or force/Torque) resulting from less than optimal combustion within the cylinders; as less fuel/air gets in (as RPM rises); and therefore it results in a lower maximum Torque figure. -Horse Power-: can be simply thought of as the cumulative amounts of individual Torque instances (resulting from combustion) that, as the engine’s crankshaft (a rotational object) speed increases and accumulates (as RPM climbs) all the poorly filled cylinders, to create an accrued force; that often (above 5000 RPM) equates to a force - even if/when there is less (Torque) time for effective/complete cylinder filling - that can be greater than the individual peak Torque figure(s).
In effect HP is a way to explain why vehicles often accelerate (with but with less force) faster even though their engine’s Torque diminishes; and this is why HP is often associated with objects that move in a straight line and/or linear plane. Within an internal combustion gasoline engine and above 5K/RPM its HP force will usually increase past Torque to offset the above-mentioned decrease in Torque presented by cylinder filling and other limitations; at around ~5Krpm. However, as most HP and Torque plots show, as the RPM increases the aforementioned cylinder filling and other limitations that plagued Torque grow until they will not be able to be suitably offset by the increased RPM; as there are limitations as to how long HP can offset these issues/limitations and provide an increased rate of the crankshaft’s rotational speed all whilst there is less and less time for gas exchange rates to occur. To be clear; even though there are limitations that plague Torque within internal combustion engines there comes a time (usually around 5Krpm) when the increased number of (poor) cylinder filling events will not be able to be suitably offset by the increased RPM of cylinders that are not full. Usually - especially with true high performance car/engines - they can extend their torque curve and fill their cylinders beyond the point of the average vehicle, such that their HP numbers suitably benefit even though as rpm’s rise there is less and less time for a complete charge to exist within the car’s cylinders. However, at some point, cylinder filling becomes so depleted and the Torque figure starts to drop off and/or become so low that an engine simply can not spin it’s crankshaft fast enough to both, reclaim enough of the diminished Torque and/or generate the high HP numbers that are essential to offset the poor cylinder filling (and/or BMEP) associated with increased the rpm; to increase HP. And, in fact, if it could it would only exacerbate the cylinder filling issues by providing ever smaller time frames for the air/fuel to enter the engine. So, HP is; A) Accumulated Torque. B) Simply a way to explain how quantized combustion/Torque events transferred to the cranktrain change its angular velocity/momentum in ways that produce a total force greater than that produced by Torque alone such that it can, for a given RPM range, compensate for and/or offset the decrease in Torque presented by the diminishing cylinder filling issues (and/or torque) at higher rotational crankshaft speeds. Horsepower is a form of Torque, but Torque is not a form of Horsepower. It’s worth noting too that there are 3 types of torque in an internal combustion engine; instantaneous (individual cylinder firing combustion Torque), inertial (rotating mass of crank/valve train), and composite (instantaneous and inertial Torque). Dynamometers average the peaks, troughs, and figures of these 3 out, so they don’t really give a clear insight into them. In essence what I am saying is that HP is a way to explain how the diminished returns of torque can still yield more thrust (than otherwise would be the case) due to the increasingly higher crankshaft rotational speeds that increase at a rate that offsets how quickly the torque (and therefore optimum cylinder filling) starts to drop off from poor cylinder filling. So (even though the force and velocity equations are purposeful) the crossover point just at a slightly above 5K/rpm on a HP and Torque plot is to some extent arbitrary, even though HP remains as a popular/useful means to explain how objects move in straight lines and/or linear paths as a result of engines and/or motors that rotate. And this is so because Watt’s figure of 33,000 foot-pounds per minute - as the denominator to the equations - “disturbs” and "poisons" the other equations and their components (that all have a strong/reliable quantitative relationship to science/math); effectively rendering Watt’s figure for HP and/or Torque to be as questionable and accepted as Einstein’s cosmological constant. Which also means a crossover point around ~5.2K/rpm on a HP and Torque plot is also something that should not be too heavily invested into also, even if it does seem that the engine produces more HP as engine rpm rises above 6Krpm. As such the crossover point (of Torque & HP) just around ~5.2K/rpm on a HP and Torque plot is to some extent capricious; because all the HP plot is revealing is how the increased rate of poor cylinder filling (ie; the drop off in torque) offsets the usual drop in BMEP and/or torque that is the result of poor cylinder filling. It is also why, in another video, here ( ua-cam.com/video/u-MH4sf5xkY/v-deo.html ) I explain HP and Torque within the context of quantized instantaneous/other torque/combustion events that - up until a given point - usually supply an increased Torque-force and increase in HP-force as RPM increases. I know you may have said that HP and Torque are different units, but even though that is correct, to a great extent they are also contributing to the same (force/thrust); and I substantiate that by way of inference within my above-mentioned comments. HP is simply a force-product of (and therefore similar to Torque-forces) that can possess more (HP) force than the Torque itself due to the increased rpm and/or combustion events (even if the cylinders are not totally filled due to the increasingly smaller amount of time provided for each cylinder to properly fill); but only up until the engine’s crankshaft rotation speed can no longer accelerate/increase. HP’s usefulness within the motor industry is (aside from selling cars) simply its ability to portray/describe the collection of increasing and/or more Torque-force(s) per given time - as RPM increases - in ways that allow more overall force to be converted into thrust than the peak Torque-force figure alone/itself and/or the HP would dictate. However, that said, within the motor and power train industry HP is rarely used to discuss force at RPM less than 5K/rpm, and that is because usually we are only interested in HP when it provides more force/thrust than Torque alone. Jim Stanley. EX AMG Powertrain Engineer. Electronic/Electrical Engineer. PhD Electroacoustics
Part 3 HP is just another force - one that is similar to and derived from Torque, that - for the most part - it only remains within our vernacular to explain how increasingly more/rapid (as RPM increases) collections of force are available to offset the aforementioned falling composite Torque-forces that can often offset the decrease in individual Torque-forces presented by poor cylinder filling and other high RPM attributes. Torque-force is the is the cylinder compression/expansion pressure of any 1 engine cycle at; any 1 point in time. Max Torque-force is the peak cylinder compression/expansion pressure of any 1 engine cycle; at any 1 point in time. HP-force is; A) Multiple Torque-forces accumulatively measured/averaged over time; whether or not they be the result of decreasing rates of cylinder filling and/or torque. B) Usually only employed to describe/explain how the overall force the engine generates increases as both, RPM increases and the Torque-force decreases. I hope that makes sense; as in essence as what I am saying is that - when it comes to internal combustion engines, their crankshaft’s rotational speeds will inherently come to a point (usually around 5Krpm) when complete cylinder filling can’t occur as the increasing revs provide a smaller and smaller amount of time to fill the cylinders. But the HP can still increase (as the engine rpm can still increase even though cylinder filling is not optimal) whilst the engine can spin to higher (than ~5K ) rotational speeds, as at that stage there is still enough accumulated events of (less than optimal) cylinder filling to offset the reduction in torque. This is one of the main reasons HP - within internal combustion engines - exists. To explain the phenomena of an increased force (at the flywheel and/or are wheels) despite the fact that torque and/or cylinder pressures may be dropping off because the cylinders are not experiencing the ideal gas exchange characteristics of a fully filled cylinder; those in the automotive industry turn to HP. fdPut simply the HP figure describes how an engine can still increase the force it produces whilst cylinder filling (and therefore torque) is not optimal; due to the fact that higher RPMs (up to a certain point) often offset poor cylinder filling and torque; because as the engine/crankshaft increases its rotational speed it does so for a given rate that is greater than the torque diminishes; therefore providing higher HP up until that limit when both the rpm and instantaneous torque events can no longer spin the cranktrain at increased rates. Good video. Jim Stanley. EX AMG Powertrain Engineer. Electronic/Electrical Engineer. PhD Electroacoustics
@@StormCentre88 ,,,,Read all of this concise information.....Gotta save it.....I like your last three paragraphs as closing statements......I wish I , had three more lifetimes,,,,,,I failed as becoming an Engineer..........Algebra,,Geometry,,Trigonometry,,,Calculus,,,,,it goes next into Quantum physics...............I'm lucky ,, I have a great eye and hands-on talent to be a better than good Machinist.........Weldor.......Fabricator.............................God bless the formal education of some ........Thank You,,,Jim Stanley.....
I just had to say that I have been a fan for forty years! I have bought every book you have made to my knowledge. I still refer to your books prior to building an engine. No matter the manufacturer. I have really enjoyed the PowerTec 10 videos.I just wanted to thank you for a lifetime of your hard work. I have watched in great detail your video on degreeing camshaft timing for compression and cubic inch displacement. I am not sure if I have missed it or not but do you have a formula for finding the best lobe separation for maximum power and drive ability? I am putting together a 383 sbc that has a 10.5 to 1 compression ratio. I know to set the intake centerline at 106 degrees. I haven't decided on what camshaft to run. I am trying to decide between a 107 to 110 lobe separation. I would love to hear back from you either through hear or through one of your videos.
Mr. David Vizard sir, I recall your stated static compression for your friends Chevy 427 making 600+ lb ft of torque, but I never hear you discuss effective CR, or dynamic based on the variables like IC abdc, torque at lower engine speeds, highest dynamic CR for putrid California 91 pump gas.
GREAT videos, David! I've been reading your stuff for years, and thoroughly enjoy your style. Having read your books and listening to this, my third UA-cam video from your channel, I am very intrigued by the 289 vintage racing engine you mentioned. Could you please do a spec-sheet type video on that engine? I'm not interested so much in any proprietary info, but I am a huge 289 fan, and have been since around 1967!!?? I have many parts I'm putting together for a "close-to-original" '65 Shelby GT350R build. Thanks for such informative content!
I am doing professionaly 5 years preparation of 289 heads for FIA approved classic racing. Been around 25 years prepping heads. The 289 head , and block need a lot of fine detail work to make power and reliability.... Valves we are stuck with 1.88 and 1.6 as per regulations. Intake size at the gasket fixed sizes. ( a bit smaller then Felpro gasket ). Also on exhaust, but I dont make the exhaust that big... not at all!!! keeping the port wall thick to prevent cracking...... If you use on the intake 1.88 valves, in my opinion , removing the guide is useless. Flow is not increased , guide wear shoots through the roof. Streamlining the guide works. Same for exhaust. And dont be sad if you have thermector heads with bump in exhaust near gasket. If well done , it flows even better then without.... Inner radiuses : VERY IMPORTANT. Also only flat tappets , as per regulations...No roller cams..... Chamber is opened up to create more flow AND swirl... As these are used for road racing , I keep ports small , as throtlle response is very important . Compression is pretty high , ( not high compared to modern engines...) as volumetric effeciancy is low. Hp with dual plane is well beyond 430 hp with a dual plane Edelbrock. And with Webers on it 460 hp, have done even more, is possible. Torque figures dont know exactly... but from 2500-3000 enough power to have customers happily complaining: tires spins.... also whwn shifting to next gear...short tire spin...So not more torque for these racing cars , as tires limits that. More hp might be possible......but the 289 is difficult ti get more out of. And yes...with the 351 heads on a 289....its easier..... But scruteneering is intensified as from England came recast 289 heads with 351 ports and chambers....so forget about a recast or 351 head using on your engine in these FIA approved races....... .m.facebook.com/pages/category/Business-Service/BFS-airflow-research-162541440518599/?locale2=nl_NL Hope it helps a bit....
Ez Go DV, I HAVE A VERY LOW MILEAGE 1975 SBC 400 WITH FACTORY STOCK DISHED PISTONS. I AM GOING TO PUT SOME VORTEC HEADS ON THIS ENGINE WITH THE SPRING AREA MODIFIED FOR MORE CAM LOBE TRAVEL. AND DRILLING THE STEAM HOLES IN THE HEADS. I REALLY NEED SOME ADVICE ON THE RIGHT CAM FOR THIS ENGINE. I WANT TO PUT A ADJUSTABLE TIMING CHAIN SET IN IT ALSO. THIS ENGINE WITH THE STOCK PISTONS AND THE VORTEC HEADS SHOULD HAVE AROUND 10.1 COMPRESSION. ANY HELP WOULD BR GREATLY APPRECIATED. THANKS.
David I like to work with big block ford FE, & 385 series engines & aftermarket aluminum heads are not realisticly in my budget ever. I dont work with engines as a business, just a hobby, so I'm always just working with my own equipment for fun. I have big 4x4 trucks I like to just hotrod around the country side with & enter a occasional mud run in the street classes. The last one I went to I won my class out of about 10 trucks & got second place in the open class out of maybey 30 trucks. But I would like to learn more about porting on the old oem iron stuff. Do you have any books that might help me gain some knowledge at becoming better at it? If so I would be interested in purchasing it.
Much better than the first video! I would love to know how to make my 289 make close to that power level. Obviously I can't get 97 octane. I can only get 91 in Arizona at most gas stations. What did you have to do to that 289 to get that amount of power?
Beware of methodology: I think the EU does not average MON + RON at the pump, but gives the higher of the two values in RON only. So when they say 97 octane, you are probably looking at a US equivalent of 91 or thereabouts.
You gave info how to build torque but nothing on the cfm flow or port volume of the heads to create low rpm torque at low lift that being said no lift numbers or duration/lsa for a low end application. More information toward this would help a man with not alot of money make something work
Daddy cool 😎 I have a bare block Pontiac 400 and #13 bare heads that need porting I wish he could build it for me 😎😁. The block is the thick older model not the thin crap 500557 cast of the mid 70s smod era. Its ready for a balanced forged lightened crank rods and pistons set perhaps from Butler. Everyone strokes a Pontiac 400 to 461 but they also have a 4" stroker that makes it about a 427. I would rather go with the shorter stroke with those heads or it won't be pump gas friendly
I think of power as the VOLUME of torque. Visualize torque as force. Think of a hammer slamming into a scale and seeing the reading go up. You will see a spike of peak FORCE during the strike. Visualize power as how MANY hammer strikes you make in any given time frame. This is also known as WORK. If you have a nail and it takes 2 strikes to drive it into a board that is work. Interestingly you may use a lighter hammer that you can swing faster but produces less peak force for each strike and it takes 3 strikes to drive the nail into the board. If you can swing that lighter hammer faster and make 3 strikes in less time than the heavier hammer takes to make 2 strikes... the lighter hammer just delivered more POWER/WORK than the heavier hammer even though the PEAK force is higher with the heavier hammer.
That is all true and a good way to think of it fundamentally. But it does not explain 1 fact. Acceleration is always at it peak when torque is at it's peak in any fixed ratio drive train and does not follow horsepower level at all. Legendary engineer, researcher, professor and author C.F.Taylor coined the term "unavailable horsepower" in fixed ratio drives, regarding acceleration, to describe it. This is a strange phenomenon but it explains much. Acceleration is force based not work based, with fixed ratios it mirrors only the force(torque). The only way to access the acceleration potential of peak horsepower is to have a CVT, constant variable transmission. One way to think of it is: With any particular overall ratio, maximum acceleration always occurs at peak torque - At any particular SPEED with gearing open to any ratio then maximum acceleration is at peak horsepower. This is a difficult concept but well worth understanding and essential to know about.
Hey. Is this book designed to some particular cylinder head or can the infromation be used to other cylinder heads aswell? David Vizard's How to Port & Flow Test Cylinder
I have used this as a basis for porting... Ford Essex/Cleveland, Holden 308/304 V8s and Buick 3.8 V6, Toyota 7MGTE (4 valve) 4AGE (5 valve) and Mitsubishi FTO, which was a 2.0, MIVEC V6. If success is defined by flow improvement over stock, then ALL heads did just that while retaining the stock sized valves. His books are a guide, not a full LEGO type, step-by-step, breakdown of what each head needs. Some are universal, some specific. That's where your experience falls as to how to apply what he is teaching. That and buy a flowbench. That book explains that, too.
Can anyone here give me thoughts on the power difference of a SBC with vortec heads that has an AFR of 11.0 vs an AFR of 12.5...how much power am i losing? My engine is a 388 SBC stroker, 9.3 compression, stock vortec heads, 277/277...223/223@.050...450/450 lift w1.5 cam on a 106 LSA, 102 ICL..i only made 415 ftlbs at 2800 but the AFR was fat , at around 11.0-11.5....i should be making more torque? The dyno operator said that the Stuska dyno we used usually shows 10% less power than most other dynos....i thought he was just trying to make me feel like less of a loser, but he told others the same thing? ....any thoughts? thanks.
11.0:1 is very rich, I’d definitely lean it out to 12.5:1 or 13.0:1 and make a few more pulls if you can. Also 106 LSA is pretty tight, you’d see a broader torque curve and higher peak torque at 108 LSA.
You are losing a good bit of power with that rich of a fuel to air ratio. An easy way for you to make a good bit more power is to put a set of 1.6 to 1 rockers on the intake side only. Think about that, with that small of a camshaft that will make more power
Interesting. Share my 454 build that didn't turn out. 049 heads with 2.19/1.88 valves pocket ported, flowed with high flow numbers by a head specialist with a hydraulic roller 262/272 duration 210/218 @ 50 .510 .525 lift on 112 centers. Daul plane 2161 edelbrock intake Q jet carb. 9 to 1 compression and long tube headers. Keith Black hyperutectic pistons. The engine doesn't have any power or torque under 3500rpm rpm and is a terrible gas hog in a 6000 lb 1 ton pickup for pulling. Worse engine I've ever put together and the most expensive, never do again. I believe the peanut port heads would of been way better and keep the small valves. High flow air flow numbers didn't do shit here but make it worse, no air velocity at low rpm? What u think is the problem? And my cam may be a tad to big? Want a stump puller power off idle to 4000rpm. What do u recommend?
You know? Head Porting is like a secret. You know what it does. You don't get the reward until, Someone rides in your car or truck & says. This thing runs GOOD! You already knew that. But they didn't yet. And it's just my TRUCK. Wait till I Port it! You don't have to ride in it. I Do!
Hello. I use various books written by Mr. Vizard and the content presentet was often an eye opener for me But. The title here says "Torque vs Horsepower". And in the whole video I can see no real connection to the title. Greetings. Martin
Maximum torque per displacement is meaningless when talking about performance engines. Even BMEP or IMEP is meaningless. The only thing that counts is the integral of horsepower within the used rpm range.
I didn't know his daughter passed. I been watching David's vids for about 6 months. I myself had extreme depression and anxiety and his voice and information I been putting on late at night. Its not the world us born before 1980 grew up in.. This man knows his stuff. No doubt
Funny you use the Ft/Lbs per C.I. instead of HP per C.I. I understand why you do it but, thru the modern day HP Torque equation and that equation's 5252 variable, HP and TQ are joined at the hip. I bought Vizards books back in the early 90's. It taught me to look at efficiencies or the lack thereof and how to qualify those efficiencies. First, the reasoning behind HP and Torque. The early engineers thinking of power and rotational force (torque), at a flywheel, was:
The linear distance covered at the circumference of rotation is a product of the radius and angles covered. Therefor:
linear distance = radius x angular distance
Further:
linear distance = linear speed x time
Ergo: Power is,
radius x angular speed x time
Finally we can say:
Torque = radius x force
This can be transposed as:
Force = torque ÷ radius = power
Boring! Most ppl dont understand HP. Ppl thru the years have romantisized the HP variable into something its not. HP is a dimensionless unit. Not until you add Displacement and RPM via the use of Radians can HP be measured. TQ on the other hand can be measured; without any other variable. Prior to the 1870's TQ was known as the Moment of Force. The HP Tq equation was created to qualify TQ per minute per second; aka, RPM. I'll try to be quick here. Radians, regarding Circular Functions such as Rotational Frequency as applied to an engine's flywheel have 2pi for one rotion; 1 RPM. Half a rotation is 1pi or half a Radian. So, 3.14159 is 1pi, while 6.283 is 2pi.., 1Radian, or 360°. Keep that to the side for the moment. James Watt back in the late 1600's qualified HP with his 33,000 ft/lbs per minute equation or 550 HP per second. However, RPM was never qualified. To qualify HP we take Watt's equation one step further. Take the 2pi per rotation and divide it by 60 seconds.
6.283 ÷ 60 = .1047166
This number gives us Radians per second. Now divide Watt's 1/HP per second number by Radians per second.
550 ÷ .1047166 = 5252
There is your Time Qualifier for HP. In other words, how efficient or inefficient is TQ being utilized at any given RPM.
You can also use the 33,000 number and divide by 6.283.
33,000 ÷ 6.283 = 5252
The 5252 variable is nothing more than a "Time" qualifier of Torque. By default once Torque is qualified into a Per Minute Per Second equation, you have also qualified or Time Stamped HP per minute per second for any given RPM. There's the skinny on the HP, TQ, RPM, and the 5252 equation. Some say HP doesnt exist. That is an incorrect conclusion. HP, without Displacement and RPM, doesnt exist is a correct conclusion
--Edited for typo's--
@@kevinshasteen5682 said "James Watt back in the late 1600's qualified HP with his 33,000 ft/lbs per minute equation " ... I just want to add that Watt was selling a steam engine to replace horses that were lifting water out of mines with ropes and pulleys. An 8 Horse Power engine would do the work of 8 horses, including the resting horses and the ones walking backwards to re-set the bucket for the next load of water. An actual draft horse can make 16 Horsepower for a few minutes then needs a break.
A Tour De France cyclist makes 2/3 Horsepower during the race, then there's the guy who pedaled the plane across the English Channel.
Horsepower is a really handy way of comparing cars and motorcycles.
@@peterdarr383 I used to ride a mountain bike long distance for exercise. Furthest I ever went was 55 miles; nothing like the Tour De France guys - those guys are in a league all their own. One interesting tid bit on James Watt. In his days, late 1600's to early 1700's, it was a bragging right to obtain a patten/copyright from the King or an Engineering Guild, also regulated by the king, for any new idea to help distribute your product. Even though James Watt never qualified Torque Per Minute Per Second (per RPM), James Watt had created a Pressure Wave signature for his Steam Engine Cylinder he built but never applied for copyright/patton on his Pressure Wavw tech; and kept it secret, hence his reputation for always being able to build a more efficient engine than others. It took the engine building world another 100 years to catch up to his Pressure Wave graphing technology. Must've been amazing times in the early days of Engine Modeling.
@@kevinshasteen5682 Thank you for writing out this explanation of TQ and HP. This stuff is fascinating
@@kevinshasteen5682 Actually, can you answer some questions for me?
1. Why do HP and TQ appear as two separate lines on a dynamometer if they are derived from one another? Asked another way: why do people measure both variables if they are part of the same equation? Couldn't/shouldn't we just be measuring power with one line and call it a day?
2. If TQ and HP are so intricately related (which I believe they are), how is it that Torque can drop off so rapidly, but HP continues to rise through the RPM range? And why does HP normally start to take off right around the time TQ drops? I haven't done the math, but the increased RPM doesn't seem like it would make up the difference.
3. I like your explanation that HP is a measure of how efficiently torque is being applied at a given RPM. What affects the ability of the torque to be applied? If it's an engine-only dyno (not a rear-wheel dyno), it can't be the transmission, driveshaft, rear differential, or wheels. What parts/processes in the engine make the torque be applied more efficiently at some RPM and less efficiently at others?
4. How the hell does a dyno measure Torque? I've always wondered that. Is it just that the spinning drum can tell how much force is being applied to it (if it's that kind of dyno) and can somehow calculate TQ and also differentiate it from Horsepower?
This gentleman is extremely knowledgeable.... I enjoyed watching this video....
Great info. Thanks.
Yes he is and highly respected in the performance industry
I found David in recent months,what a wealth of knowledge,ive rebuilt a bunch of engines but just went by factory specs of cams etc.Then I watch his variable adjustable cam drive and cams need to talk /match heads and on and on.
Thank you for documenting & sharing your knowledge for the kids coming behind you. It’s gracious and invaluable.
Dear Mr. David Vizard. I love your books and mow THIS! This is really cool. One suggestion, maybe consider using a wireless microphone on your collar. If you don’t take my suggestion I will still watch everything you put on your channel. You’re one of my personal heroes. Keep up the good work.
I watch your channel most every night. I just subscribed per your request. Have read several of your books over the years and they are second to none for the info I seek. Thanx so much sir and carry on.
David. You are the only voice of reason on youtube.
Thank you David for many years of dedicated information sharing.
I followed as a kid ‘Gods Manual ‘ to the series A and managed to make my Mild road build clubman 1275 ‘feel like a 1380 to the Dyno man .
Never seen your videos until Richard Holdener mentioned you in one of his.
Hope you carry on for many more years !!
He’s one of the best to give you the information without all the hoopla. A truly good man with vast knowledge on the engineering of a motor for the job.
So glad Uncle Tony told me about this channel. I just wish I had known about it sooner
Thank you sir for providing all the information you have to the public. I will be buying more of your books in the future.
Just the beginning of an extremely deep dive.
Thanks very much, I have your porting book and how to make big power on a budget BBC and your Holley carb tuning book , I have leaned loads of information and love them .
Thank you for these videos. They are very informative.
Hey david. Love the research you have done, and always enjoy learning new things from your books and videos. You and the late Bill Metzner (lazer cams) have taught me a lot, especially on lsa. You guys are the only ones who are on the other side of the LSA spectrum , from the cam companies. I built a 406 sbc with 11.5-1 comp and a mech flat tappet on a 104 (custom) LSA. My boys thought I was nuts!. But it ran way better than expected, and they had a blast with it. Thank You!
Chris, I knew Bill - good guy!
Mr. Vizard, I thoroughly enjoy watching your videos and that you share your experience and expertise with us. I have learned a great deal from you. Long story short… I experienced what a bowl port and port matching can do as a teen. I have been an enthusiast ever since. I am watching your naturally aspirated vs boosted/nitrous discussion now. I value your opinions. Keep it up and God Speed!
Again David. Your knowledge comes shining through TY..
..
Thank you for these videos, so useful, hi from argentina buenos aires
30+years ago there was a books How about building small block chevy I learned alot from it thank you David
i would love to know how to take advantage of long con rod ratios and ir intakes . all of the local speed shops race car specialist in my area think i am backwards or nuts, ive read most of your books they are very good well worth the money. thank you for your amazing knowledge .
CBob's Country Bunker his books state that properly tuned IR intakes are the best, but incredibly expensive. Within the parameters of a production block, con rod ratios aren't worth too much power. Bad ratios are worse with lower compression engines, as high compression does most work towards the top of the downstroke, minimizing side-loading.
what engine? i'll help. i'll give you my calculus blueprint of engine and you double check it or use it or get some one to compare theirs. what kind of engine do you want? chevy , ford , mopar? other? number of cylinders.
@port nut yeah in the end, stuffing as many cubic inches in to the block will get the most power, even with the additional piston wall friction. As RPM rises, frictional losses increase exponentially. So, for a street motor, with about 10.5:1 compression, and a Max room of about 6,500, don't even worry about rod length.
@port nut that said, long rods increase tdc dwell, allowing the charge mixture more time to enter the cylinder. Potential "5th stroke" power is improved. (That's the ability of the tuned exhaust to create a negative pulse during overlap. Get that timing right, and you have effectively "super-charged" the cylinder with more air than the volume of the cylinder should hold.) That's the pro-stock way. Like greater than 115% efficiency.
The "width" of the torque curve & where torque is made are also important. The lower the rpm & longer the engine builds good torque, the more useable it will be on the street. You can build a 302 with about 10:1 compression, flat juice cam, ported OE big chamber heads, & a dual plane intake that will build more mid range torque than a 460.
Oh, I believe you. Do you also have a bridge to sell me?
@@fasteddy Only the one in your mind connecting the use of the standard mentality & failure to grow.
i have used all your books on small block mopar and were very helpful helped me to win many street races. wish you would get into the gen 3 hemi and see what you can do
i would love to be at next seminar
yeah chevy 355 street builds getting 380 tq, less than the 400tq of a 302 ford is the common build. and 350 sbc that get 400 tq and 415 hp round abouts still a far cry of the 400tq and greater hp of the 302 on a thought out attention to detail build like david vizard'S builds and studies. What a great science it is, engine building.
Well, that was as light a brush stroke as possible on a fairly complex subject. Almost told us something.
David, love your tech, however, referring to the 351. Please in the future can you designate. Windsor, or Cleveland. Thank u.
I always hear about torque, but at what rpm? I'm looking for ways to make torque at the 2500 rpm for pulling. I see no discussion on this
Theoretical CR in a motor is related to cam events so wouldn't it be OK to use actual cranking pressure to be able to use a higher theoretical CR? I've been using the same (cheap) compression tester for about 30 yrs using a max cranking pressure of 220lbs/in2 with good results. The theoretical CR is usually around 13~15:1, BUT, it's on air-cooled motorcycle engines with probably easier/better heat transfer with small combustion chambers
Hello my friend I just wanted to start thanking you for all the correct information on all your videos, I have a 2010 grand cherokee wk1 srt8 6.1 hemi and recently got a bad lifter lifter so now I'm in the process of swapping a better performance camshaft on my stock 6.1L hemi 370 CI with a 10.2 to 1 compression ratio with 2.08'' intake valve diameter & 1.60'' exhaust valve diameter and has been searching online for the specs of my stock cam ( with no luck ) to be able to compare it to the many different aftermarket options out there so I can make the right decision on what camshaft/springs etc to go with on the stock torque converter in order to get the most physically possible torque/power out of my engine which I'll use on the streets every day so PLEASEEEE if you don't mind and can provide me the specs/manufacturer for the correct camshaft I need it'll be greatly appreciated, THANKS IN ADVANCE
Amazing knowledge, thank you for sharing!
I’m working on sending you a gif of my first lesson of porting aluminum
99% correct there are a couple other factors that will increase engine efficiency. IE torque. Thanks
Loved the original A series book from Mr Vizard 30+ years ago. I do wish he wasn't so dull to listen to.
Hey: Tony Robbins can't wrap his head around physics. I'm ok leaving this content to the real pros.
But youtube has rescued you with one little trick: use their 1.25x speed setting, and it presents better with the quicker pace. Problem solved.
a compliment wrapped in an insult. You are the dull one here, Paul
Flinch, thank you, I would’ve never thought of that. Dave S. Not so much. I agree. David Vizard is has great knowledge, but is hard to listen to. I think it would help if he used a microphone on his collar. God bless UA-cam.
Hi David sorry I missed your seminar in November , I had some issues with my back, when is the next one? I cant wait to go. Thank You
I have a suggestion for y'all Dave. How about a feature on your REC 18 degree entry?
I GOT A 1990 K5 BLAZER 5.7 WITH ECU GOT ENGINE REBUILD GOT THE BLOCK BORED 30 OVER AND DID A FEW UP GRADES IM USING EX262H CAM IN IT WHAT WOULD BE A GOOD COVERTER TO USE I TOOK THE STOCK ONE OUT..AND GOT 2000 TO 2400 STALL .. IS THAT GOOD WITH THAT CAM
Nice mug... bacon does make everything better - including this presentation, I assume? Another fine presentation for those of us looking to know more.
bacon is chocolate for men
*Part 1*
You're right in a lot of senses but HP is a misleading component to the uninitiated. As to some extent the crossover point (of Torque and HP) is merely a function of what, years ago, one person (Mr. Watt) roughly assumed the work a horse could do; in order to normalize predictions/calculations related to horse and work requirements.
After all, there is no one ideal horse that is identical to all others, for all years.
Many other variables also exist.
You can't have HP without torque.
Your view (or at least what I understand it be) is correct; in that Torque is force over a distance and HP a product/derivative of it.
However, I find it easier to consider Torque as a force associated with objects that spin and/or rotate - it is simply another force, albeit an angular one/force.
HP is also a force - a force that is (derived from Torque and) usually associated with objects that move in a straight or linear path.
To a great extent HP (within the car industry) only exists because yesteryear’s engineers and mechanics were befuddled about why internal combustion engines continued to generate higher peak force/thrust numbers at times when the BPEP of the engine was falling most due to poor cylinder filling.
It is correct to assume that the car with the greater HP figure will (at some point {provided both cars have the same weight and aerodynamic drag} usually win the race) enable the car it is fitted to to experience the greatest forward force/thrust - but usually that’s only for that limited amount of time when the car with the greater Torque (but lower HP) maintains complete Torque (cylinder filling).
So long as that happens forward thrust will usually to be greater than that produced by, say, another competitor car with less Torque and less peak crankshaft rotational speeds; and this is so because the engine/car will accelerate faster due to the faster engines speeds made available by way of the accumulation rising rate of the crankshafts rotational speeds (even though the cylinders are not completely filling and torque may be compromised).
This is one reason why electric cars with less maximum HP than internal combustion engine vehicles often beat them off the mark and sometime across the entire ¼ mile. Their Torque(and HP) are either consistently higher for a longer period of time than most internal combustion engines, or the internal combustion engine has a lower Torque specification.
Same for a lot of diesel engines out there that produce significant Torque figures and relatively low HP figures. If these engines were to produce their max/high Torque output at really low RPM (as most do) and also maintain that for a few thousand revs (as most do), then usually they will deliver - to the tail-shaft force and/or thrust - greater numbers and cylinder filling that will allow the electric vehicle within which that harnesses it, to beat a typical gasoline engine that must climb to its rev ceiling to access the peak HP.
It may sound like I am splitting hairs here, but it is these nuances that confuse people about Torque and HP; as some people can't understand why one car does not beat another (with an equivalent engine, mass, ect) when/if the losing car has greater torque.
A good understudy (and video opportunity ) as to how Torque offsets HP and vice versa, is how the La Ferrari, McLaren and Porsche Spyder perform in a ¼ mile drag race. They all have differing Torque shaping systems of either the electric or manifold compression sorts, or both; and it is interesting to note how all the trade offs - in internal combustion engine and electric motor power/Torque, and overall weight, turbocharger lag, and peak available current to the electric motors - play out.
Another good understudy as to how Torque offsets HP and vice versa is within Audi’s range of turbocharged 6 and 8 cylinder offerings (with high Torque figures in low RPM) compared to the naturally aspirated (but high HP) Audi R8.
-Torque-: I find it easy to explain Torque (for an internal combustion engine) as the peak pressure (or force resulting from combustion and/or BMEP) in the cylinders at any 1 point in time.
This is (loosely) the BMEP approach to explaining Torque. Peak Torque of an old steam engine is at peak pressure; and that holds within reason to be the same for the internal combustion engine. When the pressure between the cylinders and head is at peak pressure or peak BMEP, this is where the maximum Torque is.
Obviously there are differences; but there are also a lot of similarities.
Jim Stanley.
EX AMG Powertrain Engineer.
Electronic/Electrical Engineer. PhD Electroacoustics
Part 2
Anyway, (and here is the kicker) as the engine’s crankshaft (a rotational object) speeds increase there is less and less time for effective/complete cylinder filling, so naturally this limitation on gas exchange will dictate a lower peak pressure (or force/Torque) resulting from less than optimal combustion within the cylinders; as less fuel/air gets in (as RPM rises); and therefore it results in a lower maximum Torque figure.
-Horse Power-: can be simply thought of as the cumulative amounts of individual Torque instances (resulting from combustion) that, as the engine’s crankshaft (a rotational object) speed increases and accumulates (as RPM climbs) all the poorly filled cylinders, to create an accrued force; that often (above 5000 RPM) equates to a force - even if/when there is less (Torque) time for effective/complete cylinder filling - that can be greater than the individual peak Torque figure(s).
In effect HP is a way to explain why vehicles often accelerate (with but with less force) faster even though their engine’s Torque diminishes; and this is why HP is often associated with objects that move in a straight line and/or linear plane.
Within an internal combustion gasoline engine and above 5K/RPM its HP force will usually increase past Torque to offset the above-mentioned decrease in Torque presented by cylinder filling and other limitations; at around ~5Krpm.
However, as most HP and Torque plots show, as the RPM increases the aforementioned cylinder filling and other limitations that plagued Torque grow until they will not be able to be suitably offset by the increased RPM; as there are limitations as to how long HP can offset these issues/limitations and provide an increased rate of the crankshaft’s rotational speed all whilst there is less and less time for gas exchange rates to occur.
To be clear; even though there are limitations that plague Torque within internal combustion engines there comes a time (usually around 5Krpm) when the increased number of (poor) cylinder filling events will not be able to be suitably offset by the increased RPM of cylinders that are not full.
Usually - especially with true high performance car/engines - they can extend their torque curve and fill their cylinders beyond the point of the average vehicle, such that their HP numbers suitably benefit even though as rpm’s rise there is less and less time for a complete charge to exist within the car’s cylinders.
However, at some point, cylinder filling becomes so depleted and the Torque figure starts to drop off and/or become so low that an engine simply can not spin it’s crankshaft fast enough to both, reclaim enough of the diminished Torque and/or generate the high HP numbers that are essential to offset the poor cylinder filling (and/or BMEP) associated with increased the rpm; to increase HP.
And, in fact, if it could it would only exacerbate the cylinder filling issues by providing ever smaller time frames for the air/fuel to enter the engine.
So, HP is;
A) Accumulated Torque.
B) Simply a way to explain how quantized combustion/Torque events transferred to the cranktrain change its angular velocity/momentum in ways that produce a total force greater than that produced by Torque alone such that it can, for a given RPM range, compensate for and/or offset the decrease in Torque presented by the diminishing cylinder filling issues (and/or torque) at higher rotational crankshaft speeds.
Horsepower is a form of Torque, but Torque is not a form of Horsepower.
It’s worth noting too that there are 3 types of torque in an internal combustion engine; instantaneous (individual cylinder firing combustion Torque), inertial (rotating mass of crank/valve train), and composite (instantaneous and inertial Torque).
Dynamometers average the peaks, troughs, and figures of these 3 out, so they don’t really give a clear insight into them.
In essence what I am saying is that HP is a way to explain how the diminished returns of torque can still yield more thrust (than otherwise would be the case) due to the increasingly higher crankshaft rotational speeds that increase at a rate that offsets how quickly the torque (and therefore optimum cylinder filling) starts to drop off from poor cylinder filling.
So (even though the force and velocity equations are purposeful) the crossover point just at a slightly above 5K/rpm on a HP and Torque plot is to some extent arbitrary, even though HP remains as a popular/useful means to explain how objects move in straight lines and/or linear paths as a result of engines and/or motors that rotate.
And this is so because Watt’s figure of 33,000 foot-pounds per minute - as the denominator to the equations - “disturbs” and "poisons" the other equations and their components (that all have a strong/reliable quantitative relationship to science/math); effectively rendering Watt’s figure for HP and/or Torque to be as questionable and accepted as Einstein’s cosmological constant.
Which also means a crossover point around ~5.2K/rpm on a HP and Torque plot is also something that should not be too heavily invested into also, even if it does seem that the engine produces more HP as engine rpm rises above 6Krpm.
As such the crossover point (of Torque & HP) just around ~5.2K/rpm on a HP and Torque plot is to some extent capricious; because all the HP plot is revealing is how the increased rate of poor cylinder filling (ie; the drop off in torque) offsets the usual drop in BMEP and/or torque that is the result of poor cylinder filling.
It is also why, in another video, here ( ua-cam.com/video/u-MH4sf5xkY/v-deo.html ) I explain HP and Torque within the context of quantized instantaneous/other torque/combustion events that - up until a given point - usually supply an increased Torque-force and increase in HP-force as RPM increases.
I know you may have said that HP and Torque are different units, but even though that is correct, to a great extent they are also contributing to the same (force/thrust); and I substantiate that by way of inference within my above-mentioned comments.
HP is simply a force-product of (and therefore similar to Torque-forces) that can possess more (HP) force than the Torque itself due to the increased rpm and/or combustion events (even if the cylinders are not totally filled due to the increasingly smaller amount of time provided for each cylinder to properly fill); but only up until the engine’s crankshaft rotation speed can no longer accelerate/increase.
HP’s usefulness within the motor industry is (aside from selling cars) simply its ability to portray/describe the collection of increasing and/or more Torque-force(s) per given time - as RPM increases - in ways that allow more overall force to be converted into thrust than the peak Torque-force figure alone/itself and/or the HP would dictate.
However, that said, within the motor and power train industry HP is rarely used to discuss force at RPM less than 5K/rpm, and that is because usually we are only interested in HP when it provides more force/thrust than Torque alone.
Jim Stanley.
EX AMG Powertrain Engineer.
Electronic/Electrical Engineer. PhD Electroacoustics
Part 3
HP is just another force - one that is similar to and derived from Torque, that - for the most part - it only remains within our vernacular to explain how increasingly more/rapid (as RPM increases) collections of force are available to offset the aforementioned falling composite Torque-forces that can often offset the decrease in individual Torque-forces presented by poor cylinder filling and other high RPM attributes.
Torque-force is the is the cylinder compression/expansion pressure of any 1 engine cycle at; any 1 point in time.
Max Torque-force is the peak cylinder compression/expansion pressure of any 1 engine cycle; at any 1 point in time.
HP-force is;
A) Multiple Torque-forces accumulatively measured/averaged over time; whether or not they be the result of decreasing rates of cylinder filling and/or torque.
B) Usually only employed to describe/explain how the overall force the engine generates increases as both, RPM increases and the Torque-force decreases.
I hope that makes sense; as in essence as what I am saying is that - when it comes to internal combustion engines, their crankshaft’s rotational speeds will inherently come to a point (usually around 5Krpm) when complete cylinder filling can’t occur as the increasing revs provide a smaller and smaller amount of time to fill the cylinders. But the HP can still increase (as the engine rpm can still increase even though cylinder filling is not optimal) whilst the engine can spin to higher (than ~5K ) rotational speeds, as at that stage there is still enough accumulated events of (less than optimal) cylinder filling to offset the reduction in torque.
This is one of the main reasons HP - within internal combustion engines - exists.
To explain the phenomena of an increased force (at the flywheel and/or are wheels) despite the fact that torque and/or cylinder pressures may be dropping off because the cylinders are not experiencing the ideal gas exchange characteristics of a fully filled cylinder; those in the automotive industry turn to HP.
fdPut simply the HP figure describes how an engine can still increase the force it produces whilst cylinder filling (and therefore torque) is not optimal; due to the fact that higher RPMs (up to a certain point) often offset poor cylinder filling and torque; because as the engine/crankshaft increases its rotational speed it does so for a given rate that is greater than the torque diminishes; therefore providing higher HP up until that limit when both the rpm and instantaneous torque events can no longer spin the cranktrain at increased rates.
Good video.
Jim Stanley.
EX AMG Powertrain Engineer.
Electronic/Electrical Engineer. PhD Electroacoustics
@@StormCentre88 ,,,,Read all of this concise information.....Gotta save it.....I like your last three paragraphs as closing statements......I wish I , had three more lifetimes,,,,,,I failed as becoming an Engineer..........Algebra,,Geometry,,Trigonometry,,,Calculus,,,,,it goes next into Quantum physics...............I'm lucky ,, I have a great eye and hands-on talent to be a better than good Machinist.........Weldor.......Fabricator.............................God bless the formal education of some ........Thank You,,,Jim Stanley.....
I just had to say that I have been a fan for forty years! I have bought every book you have made to my knowledge. I still refer to your books prior to building an engine. No matter the manufacturer. I have really enjoyed the PowerTec 10 videos.I just wanted to thank you for a lifetime of your hard work. I have watched in great detail your video on degreeing camshaft timing for compression and cubic inch displacement. I am not sure if I have missed it or not but do you have a formula for finding the best lobe separation for maximum power and drive ability? I am putting together a 383 sbc that has a 10.5 to 1 compression ratio. I know to set the intake centerline at 106 degrees. I haven't decided on what camshaft to run. I am trying to decide between a 107 to 110 lobe separation. I would love to hear back from you either through hear or through one of your videos.
Post this on his other channel called David Vizard, this channel is no longer used.
Mr. David Vizard sir,
I recall your stated static compression for your friends Chevy 427 making 600+ lb ft of torque, but I never hear you discuss effective CR, or dynamic based on the variables like IC abdc, torque at lower engine speeds, highest dynamic CR for putrid California 91 pump gas.
This channel is dead for now, find his other channel here: www.youtube.com/@DavidVizard
Everything you said is true David, but we are waiting fo someting we dont know old mate.
Some people dont know the basics.
GREAT videos, David! I've been reading your stuff for years, and thoroughly enjoy your style. Having read your books and listening to this, my third UA-cam video from your channel, I am very intrigued by the 289 vintage racing engine you mentioned. Could you please do a spec-sheet type video on that engine? I'm not interested so much in any proprietary info, but I am a huge 289 fan, and have been since around 1967!!?? I have many parts I'm putting together for a "close-to-original" '65 Shelby GT350R build. Thanks for such informative content!
I am doing professionaly 5 years preparation of 289 heads for FIA approved classic racing. Been around 25 years prepping heads. The 289 head , and block need a lot of fine detail work to make power and reliability....
Valves we are stuck with 1.88 and 1.6 as per regulations. Intake size at the gasket fixed sizes. ( a bit smaller then Felpro gasket ). Also on exhaust, but I dont make the exhaust that big... not at all!!! keeping the port wall thick to prevent cracking......
If you use on the intake 1.88 valves, in my opinion , removing the guide is useless. Flow is not increased , guide wear shoots through the roof. Streamlining the guide works.
Same for exhaust. And dont be sad if you have thermector heads with bump in exhaust near gasket. If well done , it flows even better then without....
Inner radiuses : VERY IMPORTANT.
Also only flat tappets , as per regulations...No roller cams.....
Chamber is opened up to create more flow AND swirl...
As these are used for road racing , I keep ports small , as throtlle response is very important .
Compression is pretty high , ( not high compared to modern engines...) as volumetric effeciancy is low.
Hp with dual plane is well beyond 430 hp with a dual plane Edelbrock. And with Webers on it 460 hp, have done even more, is possible. Torque figures dont know exactly... but from 2500-3000 enough power to have customers happily complaining: tires spins.... also whwn shifting to next gear...short tire spin...So not more torque for these racing cars , as tires limits that. More hp might be possible......but the 289 is difficult ti get more out of.
And yes...with the 351 heads on a 289....its easier..... But scruteneering is intensified as from England came recast 289 heads with 351 ports and chambers....so forget about a recast or 351 head using on your engine in these FIA approved races.......
.m.facebook.com/pages/category/Business-Service/BFS-airflow-research-162541440518599/?locale2=nl_NL
Hope it helps a bit....
@@Baard2000 cheers M8 taa 👍
🔔👍
Johesiphine .... Very interesting name.
Thank you DV. 😎😎🇺🇸🇺🇸
Ez Go
DV, I HAVE A VERY LOW MILEAGE 1975 SBC 400 WITH FACTORY STOCK DISHED PISTONS. I AM GOING TO PUT SOME VORTEC HEADS ON THIS ENGINE WITH THE SPRING AREA MODIFIED FOR MORE CAM LOBE TRAVEL. AND DRILLING THE STEAM HOLES IN THE HEADS. I REALLY NEED SOME ADVICE ON THE RIGHT CAM FOR THIS ENGINE. I WANT TO PUT A ADJUSTABLE TIMING CHAIN SET IN IT ALSO. THIS ENGINE WITH THE STOCK PISTONS AND THE VORTEC HEADS SHOULD HAVE AROUND 10.1 COMPRESSION. ANY HELP WOULD BR GREATLY APPRECIATED. THANKS.
David I like to work with big block ford FE, & 385 series engines & aftermarket aluminum heads are not realisticly in my budget ever. I dont work with engines as a business, just a hobby, so I'm always just working with my own equipment for fun. I have big 4x4 trucks I like to just hotrod around the country side with & enter a occasional mud run in the street classes. The last one I went to I won my class out of about 10 trucks & got second place in the open class out of maybey 30 trucks. But I would like to learn more about porting on the old oem iron stuff. Do you have any books that might help me gain some knowledge at becoming better at it? If so I would be interested in purchasing it.
Sir I would like to know what is your most prestigious tool
Good Knowledgeable Video.
David Attenborough of engines
Very impressive 👍
Your face can be an actor in Lord of the Rings type of movie, the tavern owner guy who gave the main character a hot tip sorta role.
He could give them a tip on how to get more power out of their horses.
Love the vids!
Much better than the first video! I would love to know how to make my 289 make close to that power level. Obviously I can't get 97 octane. I can only get 91 in Arizona at most gas stations. What did you have to do to that 289 to get that amount of power?
Beware of methodology: I think the EU does not average MON + RON at the pump, but gives the higher of the two values in RON only. So when they say 97 octane, you are probably looking at a US equivalent of 91 or thereabouts.
theres about a 3 point bump.
US 91 R+M/2 is about 94 in the EU rating.
I'm sure it's a secret but... What is your personal cam specs for your 289? Is the cam degreed and how much? Lol
Any serious builder will degree a camshaft on each and every build.
You gave info how to build torque but nothing on the cfm flow or port volume of the heads to create low rpm torque at low lift that being said no lift numbers or duration/lsa for a low end application. More information toward this would help a man with not alot of money make something work
Daddy cool 😎 I have a bare block Pontiac 400 and #13 bare heads that need porting I wish he could build it for me 😎😁. The block is the thick older model not the thin crap 500557 cast of the mid 70s smod era. Its ready for a balanced forged lightened crank rods and pistons set perhaps from Butler. Everyone strokes a Pontiac 400 to 461 but they also have a 4" stroker that makes it about a 427. I would rather go with the shorter stroke with those heads or it won't be pump gas friendly
Thank you for telling, well see ya next time see ya bye bye.
I think of power as the VOLUME of torque. Visualize torque as force. Think of a hammer slamming into a scale and seeing the reading go up. You will see a spike of peak FORCE during the strike. Visualize power as how MANY hammer strikes you make in any given time frame. This is also known as WORK. If you have a nail and it takes 2 strikes to drive it into a board that is work. Interestingly you may use a lighter hammer that you can swing faster but produces less peak force for each strike and it takes 3 strikes to drive the nail into the board. If you can swing that lighter hammer faster and make 3 strikes in less time than the heavier hammer takes to make 2 strikes... the lighter hammer just delivered more POWER/WORK than the heavier hammer even though the PEAK force is higher with the heavier hammer.
That is all true and a good way to think of it fundamentally. But it does not explain 1 fact. Acceleration is always at it peak when torque is at it's peak in any fixed ratio drive train and does not follow horsepower level at all. Legendary engineer, researcher, professor and author C.F.Taylor coined the term "unavailable horsepower" in fixed ratio drives, regarding acceleration, to describe it. This is a strange phenomenon but it explains much. Acceleration is force based not work based, with fixed ratios it mirrors only the force(torque). The only way to access the acceleration potential of peak horsepower is to have a CVT, constant variable transmission. One way to think of it is: With any particular overall ratio, maximum acceleration always occurs at peak torque - At any particular SPEED with gearing open to any ratio then maximum acceleration is at peak horsepower. This is a difficult concept but well worth understanding and essential to know about.
There are a lot of 351 ford engine's.
the definition of torque is when you awake with a whiskey hard on
when you try to aim it and your feet come off ground thats torque! lol
Torque wins
thank you mr bison ,lol. close captioning sucks lol
Hey. Is this book designed to some particular cylinder head or can the infromation be used to other cylinder heads aswell?
David Vizard's How to Port & Flow Test Cylinder
I have used this as a basis for porting... Ford Essex/Cleveland, Holden 308/304 V8s and Buick 3.8 V6, Toyota 7MGTE (4 valve) 4AGE (5 valve) and Mitsubishi FTO, which was a 2.0, MIVEC V6.
If success is defined by flow improvement over stock, then ALL heads did just that while retaining the stock sized valves. His books are a guide, not a full LEGO type, step-by-step, breakdown of what each head needs. Some are universal, some specific. That's where your experience falls as to how to apply what he is teaching. That and buy a flowbench. That book explains that, too.
Good information! My English not good)) from Russian
Can anyone here give me thoughts on the power difference of a SBC with vortec heads that has an AFR of 11.0 vs an AFR of 12.5...how much power am i losing? My engine is a 388 SBC stroker, 9.3 compression, stock vortec heads, 277/277...223/223@.050...450/450 lift w1.5 cam on a 106 LSA, 102 ICL..i only made 415 ftlbs at 2800 but the AFR was fat , at around 11.0-11.5....i should be making more torque? The dyno operator said that the Stuska dyno we used usually shows 10% less power than most other dynos....i thought he was just trying to make me feel like less of a loser, but he told others the same thing? ....any thoughts? thanks.
11.0:1 is very rich, I’d definitely lean it out to 12.5:1 or 13.0:1 and make a few more pulls if you can. Also 106 LSA is pretty tight, you’d see a broader torque curve and higher peak torque at 108 LSA.
Barry.
DV's chart for LSA is based on cyl volume.
Headers are extremely important.
You are losing a good bit of power with that rich of a fuel to air ratio. An easy way for you to make a good bit more power is to put a set of 1.6 to 1 rockers on the intake side only. Think about that, with that small of a camshaft that will make more power
Interesting. Share my 454 build that didn't turn out. 049 heads with 2.19/1.88 valves pocket ported, flowed with high flow numbers by a head specialist with a hydraulic roller 262/272 duration 210/218 @ 50 .510 .525 lift on 112 centers. Daul plane 2161 edelbrock intake Q jet carb. 9 to 1 compression and long tube headers. Keith Black hyperutectic pistons.
The engine doesn't have any power or torque under 3500rpm rpm and is a terrible gas hog in a 6000 lb 1 ton pickup for pulling. Worse engine I've ever put together and the most expensive, never do again. I believe the peanut port heads would of been way better and keep the small valves. High flow air flow numbers didn't do shit here but make it worse, no air velocity at low rpm? What u think is the problem? And my cam may be a tad to big? Want a stump puller power off idle to 4000rpm. What do u recommend?
This channel is dead for now, find his other channel here: www.youtube.com/@DavidVizard
When I say, It runs GOOD. I quit PORTING.
You know? Head Porting is like a secret. You know what it does. You don't get the reward until, Someone rides in your car or truck & says. This thing runs GOOD! You already knew that. But they didn't yet. And it's just my TRUCK. Wait till I Port it! You don't have to ride in it. I Do!
Hello.
I use various books written by Mr. Vizard and the content presentet was often an eye opener for me
But.
The title here says "Torque vs Horsepower".
And in the whole video I can see no real connection to the title.
Greetings.
Martin
Torque is not versus hp
Torque moves mass--Physics 101... lol
insight not incite
Wait this a 12 minute video David, u said 5 or 10 minutes of my time
Maximum torque per displacement is meaningless when talking about performance engines. Even BMEP or IMEP is meaningless.
The only thing that counts is the integral of horsepower within the used rpm range.