Camshaft Lobe Separation Angle: The Untold Truth of LSA!! How to Pick LSA the right way
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- Опубліковано 27 жов 2022
- Today on Unity Motorsports Garage, We (David Vizard and myself) talk about LSA and how the major Cam companies get it wrong! We discuss the how and why of picking the right Lobe Separation Angle that is right for your typical street engine.
Make sure you check out David's new Channel @DavidVizard and give him a sub as he is having to start over and has lost 27k subs!
#chevy #ford #mopar - Авто та транспорт
You are a blessed man ! To be able to work with D.V. an his knowledge is priceless
I used to work for Summit Racing back in the day and I sold a lot of David's books. I have several of my own on the shelf and I find myself referencing these each time I build an engine. Great stuff!
I just went to the Summit in Georgia yesterday and was a bit disappointed to see that the only Vizard book on the shelf was the “high-perf. sbc on a budget.” That’s one of the best of his bibliography, but they could have filled another whole section with nothing but Mr. Vizard’s material.
Don't forget to hit the "Black" bell when subscribing to get a full notification every time.
I am not racing, just want torque in town with my LS engine in the 67 C10 that fell into my driveway with a "Panoramic" rear window. Or a large rear as they call it in 68. If I need to carry 30 sheets of plywood (If I could afford it) or drywall and shut the tailgate, I can. That is a truck. Put torque where you need it. Mine is that 2k-4,5k range. The next guy wants 5-6,5k range, well better subscribe to find out. Remember, Richard Holder gets his check from "Holley" now! Lots of talk, little explanation for cam's. Well, once maybe!
DK, ASE master retired.
Greg Anderson how we do it?
@@johnshackelford6965 I can't speak for Greg Anderson but the intended use, gear ratio in the type of trans (700R4) final drive (3.08:1) and tire size 245/65R16 year round tires, work great. My wife brags she beat several people on green light challenges way over a two block area. At "WOT" she says the tires squeal and thought it was the kid in the other car, until she realized it quit when she left off the gas. I did go crazy and wired the "Body Control Module" into the pickup, so I have light control, RKE, theft, power windows (OEM brackets welded onto Escalade regulators, moving pedals, door locks auto @ 7mph, warning sounds (Adaptor that plugs into factory harness), and more. DK, Omaha.
@@MCNicholasR 12:22 12:24
Two of the best experts I have ever seen in my 68 years of loving engines,!!!!!!
Thank you for the kind words. I'm no expert just an avid enthusiast! DV is truly the expert
Andy
Glad to see someone is pushing torque instead of just speaking max HP numbers. I developed a theory that since HP is torque x RPM / by 5252 then the entirety of HP depends on the measured values and a constant when it comes to a rotating shaft. There are 3 ways to increase HP and they all include torque. 1. Increase torque in a given RPM range. 2. Increase RPM while maintaining or not allowing the torque to fall off faster than the RPM increase or 3. Increase torque and rpm. Which method is used depends on a lot of different other parameters. A drag race is different than a road race that is different than stock car and offshore boat racing different from these other types of race. A 600 HP diesel or an 160 HP air plane engine at 2300 RPM are much different than a 600 HP small block running at 6500 RPM but they all depend on a measured torque number for the horse power number. Torque has no dependency on a HP number.
Engine masters and you busting out facts about cam shafts this week. This was a really good week.
Thanks for Watching! Im glad you enjoyed it
Andy
Vizard the wizard, the 'god' of engine development. Still got my 1981 Vizard spec Oselli built 1400cc classic Mini, recently rebuilt it, still goes like stink, too fast for me these days. Thank you David.🙏
Yes, your lobe separation angle determines your dynamic compression and the 'manners' of the engine.
Thank you sirs for a very informative video.
Variable valve timing changed the game completely you get the best of both ends tight on the top and wide at the bottom for smooth idle we could only dream of such a thing back in the day when the rev limiter was our foot and ears lol
That's so True, when You do the math it shows. I really didn't understand too much about the Love Separation Angle. Now I do and just wanted to Thank Y'all for taking the time to make this video as it's going to help in the Very Near Future with an Engine Build.
DV needs to put out a "Big Whomp all at Once" package deal of all his videos and all his books, and all his software. This will free people up to dig, dig, dig for years to learn more!
I'm so glad to see mr. Vizard, I was Soo worried something may happened to him, or he gave up on you tube, I haven't been notified of any videos in a while!
thanks david ! a shop i know used your info to build a mini stock pinto engine ! they DOMINATED the local track for 4 years in a row ! ALL-PRO was the name of the shop ike moore owner the track even changed rules to try to stop the winning spree yet the WINS still came in every week thank you for the years of work david n
great video, awesome to see you both together. I took DVs comments on LSA to heart and applied it to my sbc and it is great, thanks for the knowledge. I still come across those who think that a tight LSA is for high rpm racing only, but I politely point out this knowledge to them and try to get them to see the light. if not they can look at my tail "lights"
Good information, Andy and David! Sorry for your loss as well. Looking forward to more Unity and DV content!
Thanks Brother!
Marty from Western Australia.
Was just about to do my 1st cam swap on my 6L Caprice when I come across this clip. Thought I knew what I wanted, and now to what you have educated me on I'm back to the drawing boards. Thankyou for being informative and in language most can understand.
Liking and subscribing to both of yous 👌💪
Thanks for the kind words and the sub as well!
Andy
Dont get lost in this too much I did 3 months research before I chose my LS1cam what cam are you looking at if you use a vcm or crow cam they will recommend the right one for your mods but i researched and chose my own. went with a Crow Cams 229/235 on a 112 lobe sep works awesome in my LS1. Mine makes 590NM torque my cam in a 6L makes 750NM according to a dyno video ive seen.
Im an avid study of D.V., and was curious as to what you were providing.
When I heard his name, i didn't need to see more, im confident that your information is top notch.
I really needed to hear this information because I have been fed so much bullshit and spent so much unnecessary money building my small block Chev myself.
Thank you so much I have subscribed to both
Was wondering why i hadn't seen new content on DV's channel in a couple weeks.... David's knowledge is a national treasure! Always puts out well rounded informational videos! Subbed his new one and looking forward to more content from both of you guys! (Andy - constantly referring to your tuning videos. GREAT stuff) LSA is something you need to tune so that your Dynamic Compression is correct for your build too. Learned about this many years ago when i set out to really learn cams and how they work. Nobody ever talks about Dynamic Compression and how important of a factor it is.
Dynamic compression is why I stopped using calculated CR years ago when it became 'meaningless'
On motorcycles, 102-103 LSA is quite common and stock motors run at about 175psi with redline anywhere from 9,500 to 13,500 rpm ( older bikes from 1970's to 1990's )
As long as I get around 210 to 220 psi I know things will be 'fine'.
The 'calculated CR' often works out between 14 or 17:1.
Suzuki actually stated CR on early RMZ250 was 17:1 but dynamic CR is much lower with under 200psi cranking.
Mr. V, you're my small block hero. So sorry to hear about Marvin, I know he meant a lot to you.
,,,.,Thanks Andy.....That diagram you put up at 5:04 vid-time shows it all.......As a kid when I first saw that diagram in my Isky cam handbook my mind said WTF,,,,,,,looked complicated .......For me , memorizing camshaft events and piston position started my camshaft education....e. g. , INT. opens BTDC on the exhaust stroke , the EXH. closes ATDC on the intake stroke , the INT. closes ABDC on the compression stroke , and the EXH. opens BBDC on the power stroke ..........Thanks again for your work....
Thank you very much for this video, and a companion to it by David Vizard: among other things it validated a cam selection I made for the street for a Buick small block I'm building. According to the formula you and D.V. put forth, my particular engine needed a 107.5 LSA. The cam I'd selected was a Howard's SBB grind with a 108 LSA and a half inch lift at the valve. I'd been catching some flack for my pick of cams by some Buick experts, but I now feel I made the correct choice. More interesting, I have a fairly sophisticated Comp Cams software program which predicts my build will top out at 408 HP @ 5000 rpm, and 400 lbs of torque or more from 2000 to 5000 rpms on 9.6 comp ratio / 87 octane gas. I've run the numbers on the TA Performance (the Buick Guru) high dollar software and it predicts the exact same thing, 408 hp @ 5000, and the same 400 lbs torque from 2000-5000 rpms. My build criteria was, street use only, "a million pounds of torque" from 2000-5000 rpms, 5000-5500 rpm rev limit, and 87 octane gas. With the cam I chose, as validated by your LSA calculations, I feel more and more confident that my build will work out per my plans, when completed. P.S, I snuck in a stroker crank, aftermarket forged pistons and ported aftermarket aluminum heads to help out the power output.
I've already subscribed to DV's new channel Andy.
And I was very glad to do it.
The information is great.
Thank you Andy.
Take care, Ed.
You gentlemen say it all to well I want to thank you and Mr Vizard for actually having a channel with real knowledge I am always looking forward to everyone video from Mr Vizard great job guys
Thanks for helping David Andy,it means
Alot to him
We have fun! That's forsure..
So glad I saw this, and found out where DV went. Subbing to his new channel now. And keep up the great work. I'm earnestly working on relating all this info into the LS platform.
Hi Andy! I really like the way you explain how things work. A big thank you for sharing David Vizards new channel. I was getting worried since he hadn’t any new videos on his old UA-cam channel in a long time. I am glad to see that DV made an appearance on your fine channel!
Thank you Frank! That means a lot to me.. I can say I've been trained by the best!
Andy
I enjoy watching you two and learn something about the auto industry and Independence
DV. You always get my head spinning. And in the right direction. You have been such a great help 😁 when you speak it
Great video as usual Andy! So sorry for your loss David. I've already subbed to the new channel. Thanks for everything you both do!
I'm glad you enjoyed it.. I will have a video coming up talking more in detail how to use the 128 formula to pick cams
Andy
It’s awesome to see you 2 guys enthusiastic about this! Marlins passing is a shock! He was just on DV’s video 2 months or so ago!!
It was a shock to both of us. Thanks for watching
Andy
@@UnityMotorSportsGarage your welcome Andy bud!! Looking forward to seeing the next video! As I’ve just bought a 72 Ford LTD. with the 400 motor! I’ve bought one of DV’s books on porting to help me!
So glad I found this video. Great info and allowed me to find DV again. Many thanks.
Some time ago I built a spreadsheet to calc ideal cam events based on everything I could find that DV had written, included the 128 rule and LSA info. It spits out numbers just as Andy described and takes out most of the guesswork;)
Thanks DV, I have read most of your publications.
I'm working on a similar spreadsheet, but how do you tell the intake centerline angle (or how to install the camshaft relative to the crank?)
Also, I can't find much info on his rule of thumb for exhaust duration - what do you use?
Intake center line = small # subtracted from large # +90=In.CL. Same with the exhaust.
That's why when I order cans from some erasing I asked to speak to a technician to help me select the right cam for my car I tell him what I'm doing to my motor and how much compression ratio is going to have and what kind of gear ratio I got in my car really love the video keep up the good work man
Very interesting ! I have been aware of David's work for over 20 years. I am now subscribed to his new channel. ( and yours) . Many thanks.
Thanks Bob! That means a lot to both of us... Hopefully you will like the next video its a part 2 to this one...
Andy
Thanks for the video and informing about DV's new channel. Subscribed!
Well I wouldn't say it's an untold truth, it was told by David in his books years ago, which I have benefitted from greatly over the years. Thank You David!
You are right! Just untold here on UA-cam... 😆
Andy
Thanks Andy. Fantastic stuff and thanks for the heads up on DV’s channel, I was wondering why he’d posted so little lately 😊
I wondered why I haven't seen any new videos of yours for wail now I know thanks for the new update
I had been wondering what was going on with DV and UA-cam. Subbed to your new channel David and looking forward to your new videos.
Many people, including engine builders, don't realise there is a science to engine design and that through R&D and many many many hours of testing engines can be built to be more efficient and create more usable power. One of the reasons I subscribed UMG and DVs channels because I know the testing and scientific process has been worked through. Keep up the good work.
The link did not appear on my screen. What's the new channel called?
@@jeffrykopis5468 ua-cam.com/users/DavidVizard
Great discussion!
The LSA affects many aspects of performance. It can change the volumetric efficiency peak point/peak torque point. The optimal LSA is subject to the limitations/capabilities (RPM) of the engine components. I feel the bore to stroke ratio has an impact on optimal LSA/overlap.
Most of my race engines are in the 106° to 108° LSA range.
Street engines are completely different, LS engines have a wide LSA and reasons they have a broader power band. . Don't know why u would want a tight LSA. Id say 112/116 is better for street engines.
@@jessesyfie7244 Well, some people(like me) run a 5000 rpm converter on the street in a 2450 lb car with a 500+ hp small displacement(332) engine running 108 LSA. I shift it at 8500 when racing. So I don't care what the engine does under 3500, because at full throttle, it doesn't ever load that low. With a very lightweight car and a slippery converter, it works out nicely. My car is a handful when I put it to the floor, but at partial throttle, it's a very smooth, nice driving street cruiser. You can actually see it cruising along in one of my vids. Terrible fuel mileage is the only downside. lol
@@AmericanThunderwow 8500 is high. What is the engine and how can you go so high?
@@jamesmedina2062 It's a 332 cubic inch 302, bored to 4.030 and stroked to 3.25. A 4340 steel crankshaft, 5.5" H-beam rods,(giving a r/s ratio of 1.69) JE ultralight pistons and an induction system that can flow enough air to let it breathe up there.
Richard Holdener did an LSA video where only the LSA was change. 112 VS 120 LSA gave 34 ft-lb 108 vs 112 LSA gave 14 ft-lb. The peak power of the 112 was close to the 120LSA and the peak power of the 108LSA was almost 10 more rwhp than the 112LSA. LSA doesn't favor emissions, but a tighter LSA will makemore midrange torque but possibly less emissions than a wider LSA.@@jessesyfie7244
Fantastic information. I have been reading David's books for years.
The cam research for my current build has brought me here, it's only a 62 C10 rat rod pick up project, but once a lobe rounds off an engine someone else built, it's time to clean up the mess.
Subbed to both channels.
Thank you so much Andy! Got subscribed to DV’s new channel.
Thanks for sharing the new channel!
Andy you and DV make a great team!! Bless you both for sharing your knowledge and talents!! I have learned so much in such a short time regarding cams and heads I can’t thank you enough. I know you’re primarily a Ford guy and David is a Chevy guy but here is a Pontiac question. Using DV’s 128 rule the calculation comes out to 103. Working with what I have to build a basically stock 455 engine for the drag strip using race fuel. I have 2 sets stock heads, one with 72 cc chamber and 1.96” int valve and a 101 cc chamber and 2.11” intake. Oddly enough published flow numbers show the small chamber head has better flow numbers (unported). Porting the 2.11” valve head has more flow potential but I’m no expert and pocket porting without a flow bench is the best I can do and I can’t have the head cut enough to get above 10.5:1 CR without using a dome piston. The 72 cc head will be 11.7:1 CR with the flat top pistons I have. All that to ask this. Will it be better to use the small chamber head or buy domed pistons and use the large chamber head? The weak link is the connecting rod so RPM is the limiting factor until I can afford to build a stroker. Then the calculations will be different. All advice is welcome and Thanks again!!
Thank you for sharing this with us very helpful I just learned a whole bunch about cams this is awesome thank you
Thanks for the heads up on David's new channel!
"Horsepower sells cars, torque win races" > Carroll Shelby
You guys are the Best. Always very good information. I have Davids books and the videos really help clear up any of my questions. Hey Andy, when is Mixed Up Boss hitting the track in Casper?
Thanks for watching, as soon as I get it back from the header builder I hope to make it to the track soon!
Andy
Thanks guys, good overview. As long as you are talking street cars, by all means Andy you are right. As soon as you go to the boat world, things get different. It's mostly about exhaust over there. If you are running dry headers your car recommendations work fine. But, if you are running wet exhaust, you start to get into reversion issues (where you can get water into the cylinder). And since most lakes are discouraging dry exhaust, if not banning it altogether, LSA becomes a tool to try to help with reversion.
So the logical extension of this video is not only LSA, but cam install and what intake center line to use with what LSA to get a desired result ...
Hi Broc Luno! I am glad to see that you have posted on YTUBE! I should have consulted with you about cams for marine engines. Hope to see you on BITOG sometime soon. All the best.
This is interesting. The first engine I built was a 289 for my 67 Mustang back in high school.
Given my minimum wage of $2.90 an hour, you could say it was a “budget build”.
Fortunately, we had a great auto shop at school and a good community of Ford guys.
So:
Started life as a 225 hp 4bbl 289.
Build:
10:1 flat tops
Stock heads with 3 angle valve job and heavy springs (don’t remember the specs).
Full length headers
Torker-II
780 Holley
Cam was a Sig Erson High Flow 2.
Everything on top of the short block and heads was scrounged, and bought used.
That engine ran like a graped ape!!! The car had a 4 spd and 3.91 gears. Won class at the local 8th mile most Saturday nights.
No one, including myself, understood why that miss-match of used parts ran so well.
It wasn’t till years later that I looked up the specs of that cam. Yup, 108deg LSA.
I just stumbled onto a good match if used parts, starting with that cam!
Nice to get your video Andy and also the update from DV, just went and subscribed to his new channel.
Hey Andy I appreciate all the info that you and Mr. DV give to us! I've already subscribed to his new channel. I actually live in Lexington, NC, it's only an hour north of Charlotte. I hope to meet yall one day!
So helpful, keep up the good work guys.
I've always been David's biggest fan since around 1990. I've used his calculations on cam selection with fantastic results!
Along with your hat and decal, Andy, David needs a line of decals and hats also. Something like "Vizard the Wizard" (I've seen that one before) or "Torque Master", LOL. Anyways, keep the great movies going.
I have subscribed to the new channel. Thank you for sharing it.
Nicely done. I can't touch your experience, but I do note one thing that makes sense for a running engine: filling a cylinder begins with exhaust events, therfore LSA is a component of intake opening where good signal at the moment of opening intake is the focus. Managing pulse flow through an engine system functions like a tuning fork in a way: the center frequency shows up as peak torque rpm, and as you note the right [street] build increases power everywhere. As I see things, chamber volume and valve curtain area behave like an accumulator, except it dampens a negative signal instead of a positive one [as a hydraulic one would] - this does affect how cam timing is seen by the intake during the crossover event. As a simple comparison, would anyone pay attention to the volume inside a gas shock absorber relative to vehicle weight? You betcha.
Thanks for the channel update info.
DV, subscribed thanks for sharing your knowledge!
Looks like you are at David's, glad you made it.
Thanks for the info... I was suffering from Vizard withdrawal
I've subscribed to the new channel.
I feel the topic, as it’s discussed, is relegated to racing, 2WD, etc. I’ve got a 4300 lb 1980 manual bronco with a 10:1 aluminum headed 331 sbf, 35” tires, 3.73 LSD front/back, granny top loader dual plane w/ 1” open spacer roller cam 266/274 112 LSA, runs really good, 15mpg, 15” vacuum at idle, this was my first build and I feel it was mild and I aimed for mid range.
I love both of you guys channel!!!💥💥💥💥
In pure stock circle track we had a lift rule. I had isky custom grind my cam and went several degrees tighter LSA only with 248 @ .050 with spec .424 lift besides lsa it was same cam everyone was running. All other specs the same. That woke up our lap times.
Subscribed to both. Good info. Would like to apply this to my 2 valve street Harley.
Great video Andy. Thanks for helping DV out with his channel. I subscribed to it several days ago, and have watched every video. For those of you reading the comments, David covers this subject in depth in his How to Build Horsepower book. I have no doubt that he also wrote about it in some of his other books. If you haven't read any of his books, I suggest that you do yourself a favour, and buy some of them. Regards Greg
Thanks for telling where this formula exists. The formula that's been stated before is by description of a cam optimised for a small block Chevy. I have something very different ... Datsun A Series 1400cc for road racing with some significant restrictions in the rules (valve size restrictions for example). Current cam does pretty well but I'm sure I'm leaving something on the table. I'm buying the book!
@@markmeller4996 yes. DV's 128 formula. The How to Build Horsepower book includes adjustments for compression ratio, canted valves, and other variables. It also talks about overlap, duration, and other cam features.
Thanks guys! So much appreciated information! I need to look up and get DV s big block chev book ,I run 454 stroked to 496 I'm running pretty good but always looking to improve, just installed AFR fully ported 325 by great head ported and haven't been to the track yet!!
Thank you guys.
Very interesting. Every day should allow the opportunity to learn new things. In keeping with that line of thinking, I have learned more new things. Excellent.
I use EngMod4T to model engines and I move opening and closing events around in order to start to close in camshafts(16v inline fours) as I find this gives me much more appreciation for how different timings alter power and curves, which directly leads to "why?" Given simulated traces of an accurately modeled engine you learn more in a few months of simulations than you could in years of dyno testing. The engines I develop tend to be roughly 4 hp/ci, so lie outside of your intended audience, but I'll be following along 😃
Are you using a current engine as a base?
Awesome video! I really enjoy this kind of tech content. Is there a way to calculate piston to valve clearance change with LSA change? I’m not a rocket surgeon so hopefully the math is easy.
That is a good question. But it really depends on the duration of the lobes.. a 220 deg on a 108 LSA will have more clearance than say a 230 deg lobe on a 108 LSA
I know that isn't a clear cut answer but with most aftermarket pistons you will have valve notches that will accept "most" cams
Andy
Subbed to both of you 👍 keep up the good content.
Sorry to hear that about your friend, and I didn't know that about you either, God bless you both. Thanks again for sharing your thoughts and knowledge ☺️,many lives in ia
13 “Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it. 14 But small is the gate and narrow the road that leads to life, and only a few find it.
Matthew 7:13-14, Certainly a bit off topic but of vital importance to everyone who wants to go to Heaven instead of Hell.
I was preaching narrow LSA
Or as Jim Morrison sung- "The gate is straight, deep and wide, break on through, to the other side."
I use a 108.lobe separation cam in my big block merlin bracket engine and it works great!
@@HarryBurgess-jm9jq Excellent feedback. I'm certainly going tight lsa on a 6.2 ls3. I want elevated torque and more power!
Great evening to you Andy , congratulations on your new job I want to say , but I am not 100% sure , but if it is I wish you the best.
Fantastic! Dave is the man!
Listening to these guys I gotta go back to school
I subscribed to Sir, David Visards new channel. I really like your content and his. BTW, did DV ever get the Small block Ford book out for purchase ? Thanks Andy.
so with BBC boat motors the conventional thinking is you need at least 114 LSA in order to avoid water reversion into the exhaust ports which otherwise would quench harden the exhaust valves and then snap - I have blown up two motors thinking it was valve guide clearance or some kind of after market head ( dart) manufacturing defect resulting in poor cooling on the exhaust guides - I am now a believer .. 114 is at least what is needed on BBC boat motors
Done Sir David. I have subscribed sir. Thank you for your years of knowledge and expertise.
Thank you for watching! And subbing to DV's new channel
Andy
Wonderful, thank you for sharing this.
Thank you for watching! I'm glad you liked it
Andy
Very interesting info. You guys should start your own cam company
Great video! Will have to check out DVs channel. I’m going to be rebuilding a big block Mopar motor for the street, will have to pick DVs brains on the right cam to use.
Thank you Andy and David. David, I did not know you had brain surgery but I am grateful you came out of it with your mind and knowledge intact. Back in the early eighties I purchased your "Performance With Economy" and I still find it useful when advising young builders in things like why their favourite drag racer has a cam that will be a mongrel on the street. I can't remember if you said it but I read somewhere that it will be hard to explain to your girlfriend's father why you need to rev your pride and joy to 3500 plus just to take off from their driveway late at night. I have subscribed to your new channel and look forward to listening to your vast wisdom. Am I a fanboy of your work, "bloody oath". I consider you a teacher that could stand together with such greats as Prof. Julius Sumner Miller, Carl Sagan, and Neil DeGrasse Tyson, just to name a few. Good luck with your new channel.
Terry from Australia.
Having played with a lot of DOHC motors the LSA is more related to making it work with the exhaust system than anything else. It's a LOT easier to move the cams relative to one another than shorten or lengthen the header primary. Relative to compression it's where the intake closes that's most important...tighter LSA (assuming 'straight up' installation) closes the intake sooner and will trap more of the charge at low rpm and this tends to help power if you're not in an octane sensitive situation. If you leave the intake CL the same...then altering the LSA is just moving the overlap and how the engine likes it depends on the exhaust system which often is 'make it fit' rather than 'this is ideal' type of affair. Lots of variables to consider and just remember that the engine is a TEAM effort and everyone must play well with one another for best results.
Well said
There's much more to it on a single cam engine. LSA cannot be changed without affecting other lobe parameters. That's why VVT on newer engines, that no one seems to like, is so important. Wide LSA is also more important in forced induction applications as it is not prone to blow your boost out of the exhaust.
Vizard is a legend. Great info guys
I recently had a cam custom ground for my particular application , Specs were based on 12 or so questions, heads ,comp ,vehicle weight, gear,ect . I know I would have fallen to the victim to a cam with too much lift , duration , l.s hp numbers. Let me just say Im glad I did.
thank so much awesome information 😀😀
Learning more as you go.
I just subscribed. I can’t wait for more videos!
Thanks Steven! We have more on the way..
Andy
Thank you I’ve been missing DVs channel and was wondering what happened
Sorry to hear you lost your mate. Subbed to the new channel straight away.
Simply put, increasing overlap (lowering LSA) causes the exhaust valve to still be flowing air outward at the same time the intake valve opens enough to begin flowing air into the cylinder, thereby using the exhaust flow to literally suck more air/fuel into the cylinder. This is almost like having a small turbo or blower installed onto the engine. The more efficient the head combustion chamber is at cross flow (BBC, BBF, Cleveland, LS), the more power this gains. Having the cylinder better filled at the BEGINNING of the power stroke is especially beneficial for the TORQUE CURVE. Street engines don't rely on horsepower as much as torque because horsepower is built at higher RPMs tan you typically use on the street. Higher compression engines (above 10ish) need slightly higher LSA to help bleed the compression off at idle/off idle speeds. Keeping the LSA as tight as possible will give you wheel stand torque.
Thanks for sharing the new channel. Already subbed. Sorry for DVs loss of a great friend.
I'm at 11.6-1 static and 9.78-1 dynamic on my 355 sbc with 2.02 intake valves and I have 108LSA solid roller cam and 234 intake and 242 exhaust duration @0.050. Intake valve closes at 42° ABDC. compression checks give me 220psi average. why would you need to bleed compression off at idle / off idle speeds? Just curious why so that I can make a change if I need to, thanks
GREAT VIDEO JUST SUBSCRIBED AGAIN YOU GUYS MAKE A GREAT TEAM, THANK YOU
Thanks Mike! We have fun together that's forsure..
Andy
DV good to see you up and about
Thanks, I learned a lot from the video.
I appreciate your comment that pointed me to David V formula
I had a temperature over 107, possibly over 108,, I can't remember things either after that, I can even forget words in the middle of saying it, and what I'm even talking about, I have gotten better over the years, I'm lucky to still be here,
Unfortunate about DV's channel, I wondered why there were no recent uploads. I have signed up 'cause I don't want to miss any more. I would like to bump into DV in my local speed shop one day, that would be trippy.
Funny that you talk about a 'bottom of the page camshaft' in a 262 SBC. That was my scenario at one point, almost. I had one of those 262 ci small blocks in a Monza and a mechanic at work brought in a camshaft for me when he heard that I was interested in an aftermarket one. I had already swapped out the 2 bbl for a small 4 bbl. I knew nothing about the camshaft so I took it in to a speed shop and asked the guys behind the counter. Well... This thing was a few years old and all we could work with was the grind number (it was a Crane). The grind number was right off the bottom of the page of what was then the current Crane hydraulic flat tappets (rollers were but a dream then) and the guys warned me to stay away from it. One of the guys said "You'd be lucky if you could get it started". Well, I believed them ( I think it was over 260* at 0.050") but the guy who owned the cam was completely pissed off that I wasn't gonna use it. "It's a small block cam so it will work in a small block". Maybe that what the cam grinders are saying with their random LSA grinds!
Okay, but now that we know the problem how do figure out the LSA we need for our particular engine. I’m in the middle of rebuilding my 351W for my wife’s street rod and I ordered a Howard’s cam, won’t ship til January, I still have time to cancel or change. I subbed the new channel DV.
In the 80's we had Super Shops and they featured Erson Cams. Further studies led me to Sig Erson testing LSA and his findings. I always run cams tighter than CC's 110 LSA.
Depends on the combination.
SIG and DV were good friends
I remember working at super shops in the early 90s