[Stan Weiss]

Originally Posted by Stan Weiss

HP is about mass air flow / fuel, or you can think about it as VE and power cycles. Lets take a 499 ci engine, bore = 4.44", stroke = 4.03" @ 125% VE and 9600 RPM it will have around 7938 lbs / hr mass air flow. At 8600 RPM to get the same mass air flow the engine would need just about 136% VE.

Stan

First let me correct myself that should be 139.5% VE

Originally Posted by cgeise

I see all this back and forth about 2.3 - 2.5 - -2.7 per cid. but I see so very few trying to get there ? The reason they don't is two fold - or three depending on approach. First for a lot of guys is the expense, there is a point that the dollar per tenth of improvement gets astronomical -- I have a chart some one did and it gets really crazy at the upper limits. Second is just plain "WHY" Id say 98% of us are some form of bracket racer or index racer, you could probably count on one hand the number of guys running true heads up, so where is the need??? I admit that SOME of the information gathered doing this kind of thing trickles down to the mass's -- but it takes a long time and some of it is not applicable to bigger engines. The last is -- it is just easier to build it bigger -- stress it less and make as much or more HP. A 400cid at 2.5 per is a 1000 hp and a high maintenance bitch to run and take care of. A 560 cid at 1.8 is over a 1000 hp and way easier to build and maintain. So - for the four or five guys that want that small engine stuff. I get it --kinda, but for the mass's I think its big muscle that seems to be the way the majority of the racing world is headed.
And we haven't even talked about power adders :-))))))))

Exactly, if we look at a 572 ci engine, bore = 4.375", stroke = 4.75" at 8400 it will have the same mass air flow at 124.8 % VE.

Stan