Inliners International Forums General Discussion Hi Performance compression ratio, volumetric efficiency, and horsepower

Hey all, got some more questions.
I know that the compression ratio affects the volumetric efficiency and therefore the power of an engine but i was wondering if theres an actual formula to figure out the rise in horsepower for a certain percentage raise in compression or volumetric efficiency?
also, how can certain engines without dual cams, produce higher horsepower with lower compression ratios?
this engine linked here has pretty close to 100% volumetric efficency on only an 8.75 C.R., besides the displacement factor, how is this possible
Why cant a 250 get 230hp on an 8.75 C.R. or can it?
thanks.

oh it can make that much HP. just depends on how much $$ u wanna spend. Get a header and upgrade the intake to a 2BBL carb, then upgrade the valvetrain to roller rockers with a higher lift rate so the engine can breathe better ( make sure the springs are made for the extra lift though) then get a cam, maybe a 264 deg. cam, get a good ignition system (pertronix dist. with MSD ignition seems like the best), port and polish the head, then top it all off with a turbo, that should get u into the 200+ HP range,

oh yeah the "link" i mentioned earlier is herehttp://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=137080&prmenbr=361
thanks for the article greg, very informative. as for the mods suggested...i have the headers and a holley 390 4 barrel, head milled 60 for a raise in CR to roughly 9.25:1, and 1.94 intake valves.
but still, now the question is how can v8s make such high horsepower ratings with lower CR's so effortlessly compared to our 6's?
is it just the fact that they have more displacement and better flowing heads?
finally, is a 230hp streetable, good fuel economy inline 6 buildable without forced induction?

a V8 is just a bigass engine and shouldnt be compared to a inline for power comparisons, it starts off with a lot more cubic inches, better flow at stock and all that. But the inline six is supperior in the bottom end, the six has a seven main as apposed to the five on a V8. the bottom end of a six is bulletproof and usually doesnt require modification, the top end of the motor on a six has severely restricted flow so that would be the first goal is to increase the flow of the engine. V8's are more readily in supply and parts are dirt cheap as apposed to the inline, but its the guys with the suped up sixes that get the most looks. the inlines also produce quite a bit of torque. the V8's have two extra cylinders than us sixers.

Its better not to compare 8 vs 6, cause as clifford performance puts it 6=8. if u want cheap power then get an 8 cylinder, its the fact that being an inliner that makes us unique, and its quite enjoyable. even now my friends are quite impressed at the guts of the inline.

a 230hp streetable is possible but if u want better fuel economy u need to fuel inject the engine. but i havent really looked at 230Hp so i'm not quite sure whats all involved, but its definitely doable, just lots of $$$$$$$$$$$$$$
i know u can get custom heads now which eliminate the entire valvetrain, but havent looked into it furthur cause custom = $$$$$$$$$$$$$$$$$$$$$$$$

http://www.canadiandriver.com/articles/jk/at_010424.htm

copy this link, caus i found an inline thats better than a V8

You can pull 200 hp out of a 250 @ 4200 rpm with 225 foot pounds of torque at 3800 rpm, and still have a very drivable and dependable street engine that sounds like it wants to kill somebody.

The 2 barrel/single exhaust 350 in grandpa's 4 door led sled runs 195 hp and puny torque. 350's are for the bolt on billet crowd, not guys with engineer boots and 90 wt in their veins!
Bob

I think the v8 verses 6 deal is that more money was spent in the last 30 years on research & development on the v8 programs. I believe in today's world 1 to 1 1/2 hp. per cu. in. is realistic wheather is be a 6 or 8 Actually when a guy chooses to use say a 8.75 to 1 compression piston it does not nessecarily mean thats all the compression that motor will develop. The combustion chamber size and the Cam configuration still affect this. A short duration cam will make more compression, like wise the longer the cam duration the less compression the motor develops. As general rule long duration cams make more top end horse power but less bottom end torque.In short,the best combination would be high compression with a long duration cam = maximum performance and of course, Quallity fuel. Paul