Here you go, Piston area and force.
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Newbomb Turk
Well-Known Member
It’s not really big enough. A B1 is the minimum head that should be on 470 inch and bigger engines.
Even with a B1 you won't do it, diminished return. and why is that?
Newbomb Turk
Well-Known Member
Probably head flow I don't know what those W8 heads are producing flow wise but kind of easy going from stock 200 cfm to aftermarket 300-350 cfm making 1.9-2.3 or so hp per cfm 550-800 hp but imagine gains get exponentially harder and expensive above that.
No. A Hemi head is. That's the big block W2, IMO.
Probably not with Shilo's. lol
Newbomb Turk
Well-Known Member
Newbomb Turk
Well-Known Member
The Hemi flows enough air but NA it sucks.
Other than outright air flow, the Hemi doesn’t do much NA.
There is more to making power than airflow.
mid 8's letting off. Down right nasty
StageV Engineering made HEMI conversion heads for B/RB's, NRE was just on this site what,..a month & a half ago talking about the Predator heads..like 470cfm ootb & mid 500's well ported, plus NRE had the Covalt 32V conversion for $10K in the 90's..the whole kit intake, heads, valve covers, pushrods, all You had to furnish was a HEMI pattern cam & headers....crickets. The only heads that went anywhere were the B1's, mainly due to Alderman/Geffrion's seasons running them, the publicity & wins sold them.
The Covalt setup made low 800'sHp w/a freaking 280° cam,....no takers, everybody skeert....it's amazing anybody builds B/RB Mopar stuff today.
OK,
Back to the topic. I should have been more specific.
Waaaaaay back in another thread, 273 claimed that a bigger piston made more hp because of the increased area. The extra area created more 'push'. Not on it's own. There is a sequence of events that occur to make this happen. The increased area allowed more air to be drawn in to the cyl, & the extra air & the increase in compression pressure generated is what pushes the piston down. The bigger piston area was a means to get more air into the cyl [ just like increasing the stroke does ]. If no more air was drawn into the cyl for some reason, then no more hp would be made with the larger piston.
I don't how many examples are needed, I have given heaps. 273, you know I am correct, it s a pity you haven't got the guts to admit it.
Here are yet more examples:
[1] You centre punch a piece of alum, which leaves a depression in the alum. You then get a punch with a flat bottom & hit it with the same force. There is no depression in the alum because the force is spread over a bigger area; the bigger area of the flat punch did NOT give a deeper depression.
[2] You are going drag racing with your Dart. You are going to replace the skinny 5" factory wheels/tyres with slicks. The contact area of the tyre/ground goes from 15 sq in for the factory tyre to 30 sq in for the slicks. Weight on the wheel is 800 lb; tyre loading on the ground with the 5" wheel is 53 lb/ sq in. Using 273 'logic', the extra area of the slick[ 30 sq in ] & keeping the same 53 lb/s in but spread over the bigger area....would require 1600 lbs of weight...when you only have 800 lbs. Totally wrong as you can see. The correct answer is the loading on the slick is 26.5 lb/ sq in, not 53....
Back to the topic. I should have been more specific.
Waaaaaay back in another thread, 273 claimed that a bigger piston made more hp because of the increased area. The extra area created more 'push'. Not on it's own. There is a sequence of events that occur to make this happen. The increased area allowed more air to be drawn in to the cyl, & the extra air & the increase in compression pressure generated is what pushes the piston down. The bigger piston area was a means to get more air into the cyl [ just like increasing the stroke does ]. If no more air was drawn into the cyl for some reason, then no more hp would be made with the larger piston.
I don't how many examples are needed, I have given heaps. 273, you know I am correct, it s a pity you haven't got the guts to admit it.
Here are yet more examples:
[1] You centre punch a piece of alum, which leaves a depression in the alum. You then get a punch with a flat bottom & hit it with the same force. There is no depression in the alum because the force is spread over a bigger area; the bigger area of the flat punch did NOT give a deeper depression.
[2] You are going drag racing with your Dart. You are going to replace the skinny 5" factory wheels/tyres with slicks. The contact area of the tyre/ground goes from 15 sq in for the factory tyre to 30 sq in for the slicks. Weight on the wheel is 800 lb; tyre loading on the ground with the 5" wheel is 53 lb/ sq in. Using 273 'logic', the extra area of the slick[ 30 sq in ] & keeping the same 53 lb/s in but spread over the bigger area....would require 1600 lbs of weight...when you only have 800 lbs. Totally wrong as you can see. The correct answer is the loading on the slick is 26.5 lb/ sq in, not 53....
Do you even read what I'm posting, I never claimed larger piston just magically makes Hp, I've said that repeatedly in this thread, we've been talking about force and torque, you keep saying if larger pistons apply more force to the crank its free Hp which is wrong and I've explained why a bunch of times.
You think you have, far as I can tell no one has agreed with your take now that doesn't automatically make you wrong but It should probably give you some pause to your confidence of being so sure your right especially with the arguments you've been using.
This isn't a great analogy to the combustion pressure (psi) on a piston, again f=pa which pistons force is equal to piston area x combustion pressure psi, you don't need all these analogies that don't represent well what's happening.
Again force = psi x area, psi x piston area = the force to the piston.
I get what you saying here and maybe someone with a better pay grade can explain it, (i got a good idea why), like I've said in how to prove me/us wrong post you would have to prove the combustion psi would be significantly different basically equal to the difference to the piston area.
But what we do know combustion pressure (psi) is based on efficiency not displacement. Like I've stated before at full power they say the psi of an engine is around 1000-1500 psi for average passenger car to basic race car and a max effort pro stock is 1600/1700 psi and maybe some other max effort NA engines go as high as 1900 psi. That's a fairly narrow range for like probably 70's turd engines to pro stock 1000-1700 so every 50-100 psi would be decent step up in efficiency, the efficiency scale I use is torque per cid which basically go from 1 lbs-ft to 1.7 lbs-ft per cid not saying it total matches up to the engine psi but looks pretty similar. 1.15 lbs-ft to 1.35 lbs-ft on a 408 would be like peak torque of 470-550 lbs-ft.
And if tq per cid somewhat correlates to psi were roughly talking 200-300 psi difference for that huge efficiency swing on that 408.
You would need to prove like in your eg. That the 383 B vs RB, 4.25" vs 4.03" that it not reasonable that these two engines can produce the same combustion psi and that they be roughly a 100 psi difference on average which seems be pretty huge difference in efficiency, and nevermind something like a 361 B vs a 273/362 4.25"stroke, 4.125" vs 3.685" which would be about 200 psi, that's about the difference of a regular race car and a pro stock.
If you can proof this not to be true, but not by useless analogies and a formula's out of a old science book. Real proof.
Stage V is still kickin.
I was hopin' so, any RB can be a HEMI with stuff already there, it was a great idea.
jos51700
Green Bearing thread connoisseur
When it comes to displacement, no.
Gotta disagree. Bigger pistons and longer strokes draw in more air (and fuel). Changing bore/displacement changes compression ratios in a given engine, and that's widely known.
Compression ratio is a determination of potential pressures, all else being equal. Increasing, for example, the bore, increases the amount of air/fuel drawn in, by the swept volume. This is in greater proportion to the combustion chamber volume (which also increases, but not as much).
So, increasing displacement does increase combustion pressures, all else being equal.
This is at the edge of my understanding of this so I'm not saying I'm a 100% right but to me the more fuel and air is in relation to the displacement difference, so at say a 100% ve and 10:1 cr a 25 cid cylinder vs a 50 cid cylinder the 50 cid should have about twice the fuel and air but has twice the compressed volume and expands to twice the total volume which I'm guessing theoretically should create similar psi.When it comes to displacement, no.
Gotta disagree. Bigger pistons and longer strokes draw in more air (and fuel). Changing bore/displacement changes compression ratios in a given engine, and that's widely known.
Compression ratio is a determination of potential pressures, all else being equal. Increasing, for example, the bore, increases the amount of air/fuel drawn in, by the swept volume. This is in greater proportion to the combustion chamber volume (which also increases, but not as much).
So, increasing displacement does increase combustion pressures, all else being equal.
harrisonm
Well-Known Member
Well, @Bewey, you are not only wrong, you are extremely rude. I can think of 100 more polite ways to disagree with somebody. I don’t like it when people are rude on this form like that. There is absolutely no excuse for being rude to other people on this forum. As for you being wrong, are you saying that an explosion of compressed air and gasoline on a 4 inch piston is going to be the exact same pressure down on the connecting rod as on a 4.25 inch piston? Because if that is what you are saying, you are wrong. A given amount of pressure on a piston of different size is the theory behind how floor jacks work.
PRH
Well-Known Member
I’m going to go way out on a limb here and guess that this thread isn’t going to change anyone’s mind.
In that regard it’s much like threads about motor oil or spark plugs.
In that regard it’s much like threads about motor oil or spark plugs.
It's more efficient to ignore you
Can you fit that in a Dart? No. So there's your diminished return. lolWhen it comes to displacement, no.
Gotta disagree. Bigger pistons and longer strokes draw in more air (and fuel). Changing bore/displacement changes compression ratios in a given engine, and that's widely known.
Compression ratio is a determination of potential pressures, all else being equal. Increasing, for example, the bore, increases the amount of air/fuel drawn in, by the swept volume. This is in greater proportion to the combustion chamber volume (which also increases, but not as much).
So, increasing displacement does increase combustion pressures, all else being equal.
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