The Five Phases Of Your Engines Power Stroke And How The State Of Fuel Effects Horsepower
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- Опубліковано 7 лют 2025
- We discussed the need for a balance of vaporized and atomized fuel for proper engine performance in previous videos concerning EFI and Carbureted induction systems, and this time we take it a step further and go inside the combustion chamber to see how these two states of fuel combine with the varying geometric situations experienced as an engine runs through its power stroke.
We break down the five distinct phases of the power stroke and talk about how various fuels like nitromethane and power adders like supercharging, turbocharging and nitrous oxide work to delay and extend peak cylinder pressure to make big power.
#engine #diy #automobile
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I've been rolling this stuff around in my head for 50 years now. Its difficult to find people to chat with about engine theory. Most peoples brains start to hurt to quickly to get into the details.
Fax
It's been decades for me, too. I don't remember where I studied rod angularity and leverage. I had a number of Floyd Clymers and Chilton books as a kid in the sixties. It really helped me in every way. 😊
Definitely hard to find.
Excellent lesson Tony, these are my favorite videos. Lots of food for thought for my 440 build coming up.
Absolutely!
It's a privilege to have access to knowledge that took you years to obtain. Invaluable information and comprehension
I couldn't have said it any better. Thanks Uncle T.
As soo as you said, "this is gonna be a long video" I said to myself, Good! My favorite kind...
You have no idea how many questions you answered in my head. Thanks for that. I got so much out of it, I had to watch It twice.
I used to think he was a cool old car guy but UT is more of a scientist.
He’s smarter than a lot of people think.
Mad Scientist combined with tinkerer, racer, extreme optimizer and teacher.
That explains why 2 strokes are inherently limited since the exhaust opens so quickly. Also explains why having a lowered exhaust port gives torque at the expense of rpm. I learned from my 2 stroke motocross experience that fuel with a FASTER flame speed makes more power for a 2 stroke and I assumed the same for a 4 stroke. Now I know why, full circle, epiphany, I actually learned something thanks Tony!
There is nothing like hitting the power band on a good 2 stroke Enduro/Motocross bike. Trying to keep the front down while still increasing the throttle was always a blast. Ah sweet memories 😅
As someone who's never wrenched on a car before aside from tightening batteries and switching tires, it was still easy enough to understand on a basic level, thanks!
Yes, that was worth every second of watching.
Love your videos. I am currently dealing with a vendor, very popular one, that sold me a car. It’s a great candidate for your show. I feel I was scammed. To put short, I got the car 2 weeks ago, and it’s sitting in my garage not drivable in fear of potential fire.the dash started smoking. Since I have discovered so many scary issues they hid from me. A car that looks like a dream on top, all that was a cover for what lay underneath. Scary situation. Watching you videos I never thought I would be a victim of fraud. Please keep doing what your doing.
So after watching his videos on the topic, you didn’t think it would be wise to inspect the car before purchasing? The saying about leading a horse to water comes to mind….
This is the single greatest video every made on the internal combustion engine.
Makes perfect sense and is a really good lead way to discussion of diesel cycle and superior lasting torque.
It's a master class level video in it's content. At a level most gear heads can understand. I watched your video a few years ago regarding the different pressure zones, it's a great precursor for this video.
Thank you. I think about this stuff all the time and this video helps me organize my thoughts.
Your natural, off-the-cuff presentations are just fine Tony, you're doing great!
Great explanation, ppl have trouble understanding the change of stroke and burn rate, also crank angles, etc. Cheers from Cold Canada.
Thank you Tony, that was excellent 👌
Great video Uncle Tony!
A very good explanation of the intricacies of the combustion process. Thanks Uncle Tony!!
It is always good to go back and look at the fundamentals.
Lots of great information, I never really thought about how the power band actually works. 45* is actually your power band on a carburetor naturally aspirated engine w/o any power adder. Thanks Tony
Jackie, Like I tried to emphasize in the video, many of the numbers I used are approximations and there are a TON of variables that dictate the exact peak pressure for any given combination. 45 degrees is a decent ballpark number, but FAR from precise.
I got so much out of that... This explanation even allowed me the understanding of why timing advance settings make such a big difference on horsepower and fuel economy. Thank you again Uncle Tony!
This is flippin' fantastic, thank you. All my life, my understanding has been "Vapor! Vapor! Vapor is everything!" and I know about Smokey Yunick's work, and I even built my own vapor carb. Now I see that combustion is something that should be extended over the crankshaft rotation. This totally changes my view of things. Gawd now I want to build an engine!
Two Stroke guys get it right, the first mod they usually do is whipping the cylinder head off and setting the squish (which is easy to do on a 2 stroke for the cost of a gasket, and usually way off from factory)
Tony, excellent tutorial. You are the assimpv of i.c.e. operation theory. I spent years around it but then had to to go make a living. Brings back memories, thanks.
Tony this is fantastic, so good.
Now you've got me thinking of how large bore short stroke vs small bore long stoke is affected by the vapour/droplet ratio, the power and efficiency tendency of one or the other.
This was a really great video thank you!
Great video on a hard topic to explain, visualize etc. So what you're sayin' is... a stratified charge, consisting of vapors, ignites. The heat/pressure wave from that first explosion ignites the liquefied/compressed fuel that creates a flame front that quickly passes over the piston generating a large pressure that puts work on a piston. Then the real work begins where additional fuel in the chamber repeats the process following the piston down as the leverage becomes more favorable. IDK - LBMF - Long Burn, More Fun. Cheers Bros!
Keep in mind, the liquid gasoline cannot burn. The process has to take atomized fuel, and turn it into vapor to get combustion.
Good video. This is good for people to know. Alot of what you said is how we in the Diesel world can make good power on tunes amd also keep it as clean as possible. 50 before amd 50 after TDC
Tony, every bit of what you explained made sense. thanks for explanation!
This is an excellent explaination as to why David Vizard gets upset with these guys saying that an engine is just an "air pump'. On top of what you demonstrated here are the effects of quench and swiirl. Thanks for your video Tony, now I can direct naysayers to this video to show that they're wrong!
UT great job taking extremely technical information and putting it into words even i can understand. I really appreciate it.
Uncle dam fantastic video pal
Truly awesome knowledge
What a beautiful explanation of a complex conundrum. Thank you.
I did learn at least 2 things I didn't exactly know about! I have some education both school and from guys with lots of experience over a couple-few decades of working on cars for fun and for a living (mostly for fun and my own vehicles). I'm kind of a stickler for certain things before I go to work on something call me a perfectionist but I just feel like if your going to do in-depth work on vehicles you need a good and proper building with the necessary tools and climate-control to do it right. Now I've done plenty of oil-chances and basic stuff in my driveway wishing the whole time I had a nice shop to make things a bit easier on my body especially since I've gotten into my 60's now.
I have to say that this is one of your most informative videos Tony and all the noobs should know this stuff. I thank you for your wisdom!
Great explanation UT. 😊
One of the best explanations ive ever heard
the best episode ever ( and have seen all) thankyou Tony.
Thanks Uncle Tony for taking the time to explain this. I'll definitely be rewatching this video!
Awesome video UTG!
Good on you, Uncle. This is a great video i see you as an uncle cause my dad is a lot like you but doesn't make videos to share the priceless knowledge.
That was a very comprehensive and relatable explanation.
Very good explanation.
I've been a master mechanic since 1988. You got it, dude. I really do enjoy. watching your channel
this is why Honda had a stratified burn chamber a rich mix to get things to make power and vapor to start the party. we need 2 types of fuel states and them timed to get the most! water injection opens door to big power as it extends power pulse and stops detonation.
Great explanation of where 30 degrees happens to prolong the combustion and increase power after TDC
Awesome video Tony 👍
Thanks, Tony! Excellent video I love it when you get into details.
Extending this line of thought to compression ratios, different octanes (rates of burn), to diesel (longer burn) becomes so much clearer in my mind. Thanks Uncle Tony!
Great info Uncle Tony, catch you tomorrow.
It was a nice explanation, thank you.
For my European thinking this episode raelly lacks mentioning the diesel engines. Those inject fuel for a long time while the piston is travelling down and the flame is burning. That is one of the secret for their good torque.
The other thing, the most effect the conrod can have on the crank is not 90deg ATDC, but when the crank centerline to crank pin line is perpendicular to the conrod. This happens sooner than 90 deg ATDC.
Awsome job. Love it when u wonder off.
Project Farm has several videos with transparent lawn mower cylinder heads, where you can watch the flame front in real time.
Very well done, even the tangents helped explain the overall concept!
That part of it doesn't change. The ignition time is variable. I don't know why I had to be a smart ass.
I haven't seen the new bike. You talked like it was straight off the showroom.
Douggy doing alright? Wishing him the best.
All I have to say is...
NOS!
BOOM!
Sorry, F&F scene gets stuck in me ol' head when I hear the word Nitrous.
It made sense to me! Droplets and vapor and when things happen are great things to know for tuning and understand why something isn't happening. Why behind the how!
This was a great video! I had a theoretical understanding of this. Nice to see it explained in a practical sense!
OUTSTANDING explanation of the phases of the power stroke and the relationship to degrees of crankshaft rotation. Would really like to hear your take on ignition spark timing following this presentation using the same engine and visual perspective to demonstrate the approximate effects of late, spot on, and retarded ignition spark timing in relationship to crankshaft rotation and piston height in cylinder. PUTG= Professor Uncle Tony's Garage! Great content.
THAT WAS GREAT !!!!!
I enjoyed this.
Vapor burns like newspaper
Droplets burn like wood
One flows into the other
Great video!
You make total sense, great video thanks.
The reason high power motors run alcohol is because even though it "has less energy", it runs cooler, burns slower, and resists detonation, therefore, allowing a longer burn without detonation, sooting up, or overheating.
Yes, I had intended to cover alcohol but the clock in my head was ticking and I ended up leaving several things out.
Its about time for a rocking chair video.
Thanks for the video Tony, very informative.
Great video UTG. Between Slag Hammer and a shinny piston I stayed focused. Lol
The problem with long burns on nitro motors is, when they burn too long, they drive the pistons out the bottom of the blocks because they can have too much pressure for too long and the piston can't get out of its way.
Therefore, the exhaust typically is still burning because otherwise the unit will grenade.
Tony, would setting the exhaust lash a few thousands looser on a regular gasoline engine, would that be benefitial to make more power or is that something reserved for like you mentioned nitro or power adders? Been watching you for an extremely long time, like you i am older and not fond of the technology but without UA-cam I wouldnt be able to watch and learn from people such as yourself. thanks my man for what you provide to us
No, there would be zero effect with anything except nitromethane or possibly an extremely high output nitrous engine.
That made perfect sense Tony . Now if You could do a Video of the Valves in relation to the motion of the Piston . Like when the Valves are open and closed in relation to the Piston going up and down . That would be great . Love all Your Videos ...
Good video,do you think you could show how the cam is and valves affect this, maybe show how a lumpy cam is in relationship to a mild cam.
Pure poetry
I have a design for a 5 injector, 3 stage combustion system just exactly for this reason.
Eventually, I will try it out on a 440RB motor block.
So a vapor engine that fired 22.5 degrees after tdc would theoretically produce massive power.
Made a lot of sense. Thank you Tony!
So with a vapor engine it sounds like you would want to have some kind of forced induction and RETARD the timing quite a bit so the power pulse would happen near the 90 degree point so its "pulse" would slap the piston right at the point of GREATEST mechanical advantage
I did propane conversions in the 80's. LP through an IMCO regulator produces only vapor down the throat. Back then it was said to equal 110 octane. I never noticed a difference on any conversion, truck or car, when driven normally. I suppose different gases and rev speeds would get different results on a vapor system as opposed to petrol.
“You can zen out on this stuff for years”….hits home
Great video
Makes perfect sense. Like the added new. Blelease! Like it!
ExcellentExcellentExcellent!!
The trick with a dry vapor induction system is to retard the ignition timing.
No one EVER talked about these things when I was younger hanging around a garage with the motor heads , Nearly every system on a modern car is not simple and depends on skilled technology . Don't take it for granted , We'd be S.O.L. without it
That goes with any subject. The deeper ya go...
Thanks for your sharing
Very nicely explained ! Easily understood the way you explained it ! Only question I had that you didn’t touch on was altering the stroke. Stroker. TDC doesn’t change so how does a longer stroke change power aside from more overall all volume but it’s all at the bottom of the stroke…
Awesome explanation Tony, but you forgot to mention that gasoline is a hydrocarbon compound that’s 13 parts hydrogen and 87 parts carbon. Since gasoline is only 13% efficient the carbon needs to be removed to properly calculate efficiency. So for example, 1 US gallon (2.858 kg) of gasoline contains 371.5 grams of hydrogen, If we drive 30 miles and we burn 2.858 kilograms (1 gallon) of gasoline, that’s 30 miles per gallon but the hydrogen is doing all the work so we can calculate efficiency more accurately by removing the carbon e.g. (30 ÷ 1) ÷ 0.3715 = 80.75 miles per kilogram of hydrogen or 371.5 ÷ (30 ÷ 1) = 12.383 grams of hydrogen per mile.
I equate gas vapor igniting and creating pressure in the combustion chamber to the effect you get when you dump gas on a brush pile and light it.
Very good video.
Thank you, Professor Tony. When can we expect some merch from Professor Tony's Hot Rod University? 🤔
I wonder what the science is behind natural gas engines and propane engines. They run in diesel designed engines usually Cummins based with spark plugs. I wonder if at those pressures the natural gas concentrates so much it liquifies or flashes before the vapor is lit. They run so clean the oil doesn’t even turn that dark.
Makes perfect sense. So why are you messing around propane?
Because it's difficult
@UncleTonysGarage Ah, we have that in common.
13:30 Happy Happy Fun Zone.😃
Great explanation. thank you, Tony.
Your the smartest fother muker i know😂😂
Thanks for teaching the science. IT AS TO FLOW LIKE A WATERSLIDE!!! This clarify a lot of what I try to explain people but they only think, just put ... aluminium heads and ... camshaft but dont understand F'all of this science
Has anyone else ever thought of putting a air fuel injector right in the combustion chamber and add more air in the chamber..i always had that thought.
Pretty much what nitrous oxide is doing.. delayed delivery of oxygen.
👏👏👏 Maestro! Thank you!
The top fuel guys dont open the ex valves sooner than they do because they cant. When they have tried they just broke parts. Nitro is still burning when it comes out the pipe.
I know, I was a Top Fuel guy for years...I'm referring back to the low volume days pre 1980's
made sense to me
Yeah we can all understand it now but what blows my brain is the mofos that invented this stuff! Crank, cam, timing etc. etc. just blows me away!
I learned a lot from this thank you. A few questions on LPG propane fuel. I know most LPG engines want ignition timing all in as soon as possible and not more that 28-30deg. advanced. Am i correct in thinking this is because it is pure vapor and ignites the flame front sooner??? Also do you think that the cooling affect of LPG slows down the burn rate for a longer burn down the cylinder??? and lastly, I would assume that the greatest LPG engine would have a huge bore to take advantage of the fast ignition of the flame front and a very short stroke as the power would be done sooner?? Your thoughts Please.
Made sense...I enjoyed it.