That , we could argue, But I don't want to. LOL. + You could really defend either position.

My position is since torque has no time element, an engine makes no force/power/ what have you at 0 rpm. RPM is the element that adds time. Time is what we need to figure work done. Work done = HP.

LOL.

Schit, I could argue with myself over that one. He, he.

But with a very limited intake manifold or what have you, you will end up with same hp but at a lower rpm. This is not always what someone wants.

In the case of an engine with a decent intake and throttle valve (carburetor) like a HP500, I agree, I'll take a 540.

In the case of the choking 502MPI intake and throttle valve (throttle body), I'll save my $ and keep the 502.

I always looked at it as engines make power. That power is measured on a dyno and we get torque value. From that we use math to get hp.

I was being somewhat of a smart azz (again) when I made that statement.

I'm with you.

I have 547CI 660TQ and 600hp .... very strong engines, push the heavy 35 Cig to 73.5 so far... the throttle response is great with the TQ where it is.... I say go 540 and do everything needed to make them right, spend the money and do it once....mine are very conservative for reliability...

Engines have variable displacements when running.

How ?

RPM.

Wanna change the displacement while it's running - change the rpm.

That's getting the topic heavy huh ? LOL.

Nope. Sorry...not trying to start a big @&$), but come on.....

Bore x stroke -/+ combustion chamber x amount of cylinders = displacement. The ONLY thing that changes this is a rod through the block......but then, you lose hp, torque and use ability.

For what it's worth....I have a pair of 5 hour Merlin 540's for sale....with blowers.....selling to finance my lawsuit against TowBoatUS

LOL.
Yes, when measure not running that's how you measure displacement. Bore and stroke. Not combustion chamber.

When running, what an engine displaces is based on physical cid, rpm, and volumetric effeciency.

So, say we have a 502 cid engine and for easy math we'll say 100% volumetric effeciency. IE: cylinders get completely full.

502 cid
4000rpm = 1,003,968 cubic inches per minute
5000rpm = 1,254,528
5500rpm = 1,380,672

So...to compare different cid engines (again leaving 100% Volumetric effeciency for easy math)
Note: below #'s very slightly rounded.

A 540cid at 5500 rpm = 1,484,352 cubic inches per minute
A 502cid at 5915 rpm = same as above
A 454cid at 6540 rpm = same as above
A 400cid at 7422 rpm = same as above
A 383 cid at 7752 rpm = same as above
A 350 cid at 8482 rpm = same as above

This is a great way to look at engines and give more insight on what has to be done to try to produce the power you are looking for when starting to decide what cid's one should be looking to build.

Remember, an engine is an air pump. It moves nothing when not running.

Nice work sb, puts things in perspective easily. My 460" engines make 600ish hp, but at 61-6200 rpm. I think I'm going to run into a prop issue trying to get them there, where as if I had 540's or 572's making 6-650 hp at 52-5400 rpm it would be a little easier to setup.

And there's the key to your point, you have to have efficient supply of air