500hp & 600hp Bench Racing thread

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Fundamentally, the “make more horsepower” idea is an exercise in getting more air/fuel mixture past the intake valve, and trapped in the cylinder to be ignited.
Head porting, hotter camshafts, HP intake manifolds, etc are all tools to that end.
Added displacement is another tool that’s effective in that effort.
 
273 said:
I'm am processing what you have said, I value your knowledge, but have to make into a workable theory.

Same with Bewy's air's density comment I'm working into my thinking.
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No one is breaking ground here, we're struggling to teach calculus to a parrot...

Here's some suggested reading: otto cycle, atkinson cycle. Read and compare, then get back to us.

Otto explains exactly where power comes from in internal combustion, including the effects of COMPRESSION and EXPANSION.
Atkinson explains why wide LSA reaps higher HP returns at high revs, see if you can figure out why/how.

The only way more cubes make less power, or even less power per cube, is if you cripple the combo.

Now, if the premise is that you want to build a 365ci engine, but can't afford or access a stroker and you want similar output (let's take this to mean comparable MPH at the track), that's a different discussion.

The idea that there's no simple answer to explain why more CI means more power is laughable. Here's a link for your reading pleasure.

PV=nRT, where R is a constant and n has to do with the mass of air (think Bewy's comment). So pressure and volume varies with temperature. This is simplified, but helps understand where work (which is equivalent to HP) comes from. If you have more volume, then any change in temperature is going to create more pressure for the same change in temperature (think combustion). Remember, 70% of the air in the cylinder CANNOT be burned (ok, that's over-simplified, but burning N isn't gonna make you power), most of the work from combustion comes from heating the surrounding gasses. If you have more gasses to start, and thus more fuel to hold your AFR, then by definition you have more volume which is going to be heated and to a comparable temperature. Which means you finish with a greater volume of gas, and thus MORE WORK which is the exact same statement as MORE HORSEPOWER.

Thus: more displacement increases power through the increase mass of gas expanded. @RustyRatRod's tacos make a return...

The only time this doesn't turn into more power in reality is when the head is so flow-limited that the charge density drops so low that the mass of the air in the cylinder is decreased and thus not equivalent to the engine volume increase.
 
PRH said:
Fundamentally, the “make more horsepower” idea is an exercise in getting more air/fuel mixture past the intake valve, and trapped in the cylinder to be ignited.
Head porting, hotter camshafts, HP intake manifolds, etc are all tools to that end.
Added displacement is another tool that’s effective in that effort.
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I 100% agree with that statement and always have.
 
273 said:
flow numbers and better cam specs, my guess would at least 550 hp
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My point was, you can't make ANY kind of decent guess, without knowing HOW BIG IS IT. You don't know if that is a 283, or a 454, and I guarantee, it will make a difference. About 200 horsepower.
You are being deliberately obtuse.
 
PRH said:
Here’s a very simple explanation of why cubes work.......but you’ll have to connect the dots.

If I tell you a head flows 300cfm....... is that enough information to be useful?
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Nope. You have to have the bore and stroke to determine at what RPM that 300 CFM will be used.

300 CFM on a 440 is going to be a low RPM a slug unless you run a bunch of duration to crutch the small cross section.

300 CFM on 340 inches will make roughly the same power, it will just do it at a higher RPM.
 
I 100% agree with that statement and always have.
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If you really agreed with that, then for real world practical use(especially as it relates to hot rod car hobby engines) there would be no argument that more cubes = more power.

If you leave everything else the same, and increase the displacement, you’ve created a means to get more combustible mix past the intake valve........ which is how the extra power is made.
 
Phreakish said:
If you can afford to fine tune those types of things on a 273, they'll pay bigger dividends on a 408. This is exactly what I mean when I say 'all things equal' - it means equal effort.

This is why your premise of 'the same parts' isn't useful in any case. What works for one is rarely the right choice for the other. The same level of effort though will reap greater power with a larger displacement.

Also, most hot rod parts are going to favor more cubes anyway. Building a high RPM screamer takes a more bespoke approach. It's not impossible to win with RPM, it's just not the type of program which can be described in a forum post.
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Like what? In 2022 there isn’t much bespoke anything.
 
Rat Bastid said:
Like what? In 2022 there isn’t much bespoke anything.
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What I mean by that is finished goods which can't just be bought and thrown together. Proper selection of valve springs, valve weights, rockers, pushrods, lifters all have to coincide with the head and the cam. Some choices automatically rule in or out others. I'm speaking from a very generalized point of view.
 
273 said:
Yes for per revolution.

He left out rpm lol
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Doesn't that go without being said? I'm starting to feel like you are trying to expose what you believe to be a flaw in the forum here. Explain to us why there is a difference in rpm.
 
19DUSTER73 said:
And an attempt to actually contribute here...I bet a TrickFlow topped 360 at 11-1 would be pretty close to 500 without getting too wild with the camshaft.
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You might be surprised a how many of those engines that are out there that don’t make that kind of power.

Every time I go to the track I’m surprised at how many 12 second 500 HP engines are out there.

I’d say your average 408 is making 470, maybe 480. Maybe.

Of course, some of that is piss poor component selection and horrible engine tuning.

Don’t get me started on the garbage chassis tuning I see. It’s horrible.
 
Rat Bastid said:
Only if the 365 is RPM limited. You have to deal with piston speed.
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A 4" vs a 3.58" stroke is a difference in piston speed at 7500 rpm of 8.75ft/s
Is that really enough to matter? peak speeds are still under 100 ft/s. With a 4" bore, the mass flow rate can be kept in the subsonic range with typical available valve sizes.

Prostock guys go over 100ft/s and still make massive power. I don't think the 4" bore is as much a crutch as thick rings, tall pistons/tall decks and crappy heads and combustion chambers.
 
300 CFM on a 440 is going to be a low RPM a slug unless you run a bunch of duration to crutch the small cross section.

300 CFM on 340 inches will make roughly the same power, it will just do it at a higher RPM.
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I’d like to hear your 11.5:1cr 660hp 300cfm Head 340 combo.
 
33IMP said:
My point was, you can't make ANY kind of decent guess, without knowing HOW BIG IS IT. You don't know if that is a 283, or a 454, and I guarantee, it will make a difference. About 200 horsepower.
You are being deliberately obtuse.
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I know what you were shooting for :)
I was hoping it was your combo is why I took a guess.

The main reason there's a power difference is you fixed the rpm, no ones denying
over same powerband rpm the larger should make more power.

If I asked sbm trick flow top end Xe285hl cam 10.5:1 cr you couldn't ballpark the hp without knowing the displacement ?
 
Rat Bastid said:
You might be surprised a how many of those engines that are out there that don’t make that kind of power.

Every time I go to the track I’m surprised at how many 12 second 500 HP engines are out there.

I’d say your average 408 is making 470, maybe 480. Maybe.

Of course, some of that is piss poor component selection and horrible engine tuning.

Don’t get me started on the garbage chassis tuning I see. It’s horrible.
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This is exactly why I point at pro racers when looking at the engineering and potential. Sprint motors, pro-stock, etc. The shade-tree guys tend to run junk. They copy some combo from some magazine article, but then skip the head porting stage and a few other important bits, put a junk trans behind it, run too little gear, and claim "it's a 500hp build" when in reality it's never been tuned and is missing 15% of the airflow it needs for the magazine cam...

If sprint guys are getting 850-900hp from a 410 with a 4.1" bore and a 3.8" stroke, then a 4" stroke can't take that much away from the potential. Emphasis on potential. The real issue is that most folks are running poorly chosen cams with poor geometry with poor heads and worse exhaust. Plenty of guys get it done on the track with a stock-spec shortblock but choose the rest wisely and crack under the 10's with a decent chassis and they still don't need to run stratospheric rev limiters.
 
Phreakish said:
You simply ignore every statement that explains it.
Expansion, expansion, expansion. More air, expanded, will always equal more power. That's the one sentance. More air = more work, and HP is work.

The ONLY time that more CID doesn't make more power is when you cripple the induction somehow, and you keep picking examples with crap heads to 'disprove' the sentance above.
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He gave you his example in post 42. And that’s EXACTLY what happens in the real world. I see it all the time.

I guy says I want to make 500 HP and I want to shift at 5500 and it has to live for 250k miles and get 15 in town and 28 on the highway.

In the real world, you can do some of it, but not all of it.

My first issue would be why in the world are you shifting at 5500??? That’s INSANE. Oh wait, it’s because they want their muscle car to drive down the road like their **** box Honda at 2300 RPM.

So you end up crutching the whole thing.

If I had to do that, I’d do a 408 and live with it. If I could get the pussy to shift (and use the correct gearing and converter for it) at say 6800 I’d drop the stroke down to 3.75 inches, use the same heads and intake with the correct cam timing and the 383 inch engine would kill that 408 all day long.

Of course, we have too many Prius types that want to hang their arm out the window and have all the folks wave to them at the stop lights.

Those I call posers.
 
Rat Bastid said:
You might be surprised a how many of those engines that are out there that don’t make that kind of power.

Every time I go to the track I’m surprised at how many 12 second 500 HP engines are out there.

I’d say your average 408 is making 470, maybe 480. Maybe.

Of course, some of that is piss poor component selection and horrible engine tuning.

Don’t get me started on the garbage chassis tuning I see. It’s horrible.
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I get it. I'm always hesitant to answer some of these due to my limited experience but I still like to engage in the conversation. I was loosely basing that guess off of my build. We made 592hp on gas with the TrickFlows at 367". Ran out of time to get really serious with tuning. The morning was riddled with non engine related issues. We ended the day with a safe tune so I was happy. His dyno is regarded as stingy as F. Everyone is down 30 hp on this dyno. Not that that matters. We got a number (600 would have been bitchin to see on that screen though). Now I have to weigh the car and see how things pan out at the track.
 
Yup, I’m climbing out of the black hole.

I’ll just keep enjoying the added power I see from running more cubes........ as unpopular as that is.

Enjoy
 
273 said:
I know what you were shooting for :)
I was hoping it was your combo is why I took a guess.

The main reason there's a power difference is you fixed the rpm, no ones denying
over same powerband rpm the larger should make more power.

If I asked sbm trick flow top end Xe285hl cam 10.5:1 cr you couldn't ballpark the hp without knowing the displacement ?
Click to expand...
No.
 
19DUSTER73 said:
You are talking about 43 less cubes. Your problem is your thought seems to be that similar top ends should make similar power on a 408 or 365. When someone starts to explain why they don't you ramble on about how the smaller motor shoulda coulda woulda if the ports were different and the cam timing is changed. That's not a comparison. Define the parameters that you feel should differ between the two engines to make them make the same or similar power and maybe someone can agree or disagree from there. This is a go nowhere endeavor until you acknowledge that you are in it for the debate/entertainment rather than the education.
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Let me see if I can help you out.

I don’t care what head you use, if the rockers are NOT a offset, that port is good for maybe, MAYBE 370 inches before it becomes a choke.

Think about this. There isn’t an aftermarket head out there (again, with non offset rockers) that can compete with the W2 head. Not one. Not even close. And the W2 head was based on 340ish inches.

The engineers that developed that head weren’t idiots. And look at the lengths they went to make a competitive cylinder head.

And from personal experience I can tell you the W2 head, FULLY ported to square, with a 2.100 intake valve and a tunnel ram is about used up at 8000, maybe 8200. That is a fact.

Now drop those heads on 408 inches and watch them struggle.

I say it all the time. Architecture matters. You can look at some of the head available for SBC engines out there. To make real horsepower they are using heads that flow over 350 CFM at .500 lift and have a port size (and a really nice shape) that 25 years ago would make a BBC blush.

I think way too many don’t understand how head deficient these engines are. And the upshot of that is it takes a bunch more cam timing to get the same RPM (at whatever RPM that we are talking about) out of an engine that is induction (and valve diameter) limited.

The best remedy for that is reduce the stroke.
 
19DUSTER73 said:
I get it. I'm always hesitant to answer some of these due to my limited experience but I still like to engage in the conversation. I was loosely basing that guess off of my build. We made 592hp on gas with the TrickFlows at 367". Ran out of time to get really serious with tuning. The morning was riddled with non engine related issues. We ended the day with a safe tune so I was happy. His dyno is regarded as stingy as F. Everyone is down 30 hp on this dyno. Not that that matters. We got a number (600 would have been bitchin to see on that screen though). Now I have to weigh the car and see how things pan out at the track.
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So make your engine 408 inches and how much power will it make???
 
Rat Bastid said:
Let me see if I can help you out.

I don’t care what head you use, if the rockers are NOT a offset, that port is good for maybe, MAYBE 370 inches before it becomes a choke.

Think about this. There isn’t an aftermarket head out there (again, with non offset rockers) that can compete with the W2 head. Not one. Not even close. And the W2 head was based on 340ish inches.

The engineers that developed that head weren’t idiots. And look at the lengths they went to make a competitive cylinder head.

And from personal experience I can tell you the W2 head, FULLY ported to square, with a 2.100 intake valve and a tunnel ram is about used up at 8000, maybe 8200. That is a fact.

Now drop those heads on 408 inches and watch them struggle.

I say it all the time. Architecture matters. You can look at some of the head available for SBC engines out there. To make real horsepower they are using heads that flow over 350 CFM at .500 lift and have a port size (and a really nice shape) that 25 years ago would make a BBC blush.

I think way too many don’t understand how head deficient these engines are. And the upshot of that is it takes a bunch more cam timing to get the same RPM (at whatever RPM that we are talking about) out of an engine that is induction (and valve diameter) limited.

The best remedy for that is reduce the stroke.
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What I was getting at is the fact that this guy wants to basically say let's use the same top end to make the same power with both engines. When someone gives an explanation as to why it won't pan out he says yeah but if we change this this and that it should work. Which is fine and it makes sense but ya can't sit there and do that with every explanation given. It's a go nowhere type of deal.
 
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