Originally Posted by 56Maynard
I think one often overlooked aspect of less cubes turning faster then bigger cu in is the VE go up with rpm on a given motor. In other words, a 500 cu in pro-stocker turning 10,000 rpm will actually ingest more then 500 cu in of air and fuel merely due to the increased velocity in the intake and heads making a ram effect into the cylinder.
So if you took a 377 turning fast enough to get 110% ve, and compare it with a slower turning 400 at 100% ve, the 377 will actually be a bigger motor in terms of flow due to the extra 10% of ve. 377 x 10 % 37.7 or 38 cu in. 377 + 38 = 415 cu in.
Anybody follow that theory of mine? I was following that 427 vs 454 thread and was waiting for someone to point that out but it never was considered in the thread.
I can understand your point, but we're taking these non-scientific terms like "RPM engine" and "loves to spin" and trying to tack on a quantitative attribute to them. The problem with both motors is that unless you spend the money on internals, you're not going to run more than 5500RPM. A 350 CID chevy motor with stock internals is about a 5500 RPM redline motor. Why then, would a 377 with the same stroke be able to rev any better? A 377 with some high buck internals will probably be nicely efficient at a higher RPM, because of the large over-square. The issue is that stock rods are going to stretch above 5500 or 6000 on a regular basis, not to mention the fact that those big 400 CID slugs on the end of them weigh more than a normal 350 slug does. So now you're talking high dollar rods, a big cam and some upper-end heads to make your 110% VE at 6700RPM. Furthermore, to do that you've lost a bunch of power between 0 and 3000 RPM and your motor is basically a race-only setup.
So I guess what I'm getting at is not only is a 400 a better overall choice, but dollar for dollar if you want to start spending money on internals and give the 400 a bullet-proof bottom end like the 377 will need, you'll see the difference even more.