upping compression, octane, cam, and hp numbers...

[navyblue2000]

from what i've seen, our rather large displacement engines have a pretty modest compression ratio of 9.4:1. I noticed too, that our engines get the job done on 87 octane, which isn't so for most vehicles out there that are considered 'performance' cars. the stock cam on our cars seems pretty conservative too. I realise the heads/cam package on ssm takes the compression ratio up to 9.6. what's the formula for how much more compression equals how much more hp? that was one question i had. octane withstanding would be my second question. what's the highest compression 93 octane could handle on our car? 10? 10.2 or so? a more aggressive cam and maybe a 1.75 rocker would see to make some decent power, without getting too in depth on the engine itself.
sometimes i wish that GM would have manufactured a 'performance' 3.8L, not just one that has lower compression and a blower, thus the L67. but maybe an NA top end engine? i think it's possible, 270 hp or so NA shouldn't be a problem...

[Patrick Javert]

I know thatif we were to switch from iron heads to aluminum heads, we would have to bupm compression up an entire point to get the same thermal efficiency. This means, we could run on 87 octane w/ 10.4:1 compression on aluminum heads w/o experiencing knock. Our engines are extremely efficient stock, even in ohv configuration. also, there are 2 variations in compression, static(bore,stroke, piston compression height, chamber volume) and dynamic compression(camshaft dependent). you can use the cam to bleed off excess air/fuel to lower compression on a given engine, or make sure a lot of air/fuel gets in and stays in the cylinder. When i get the cash together to get the ssm powerpak, I'll probly buy GMPP aluminum heads and have ssm match port and polish those, just so I can later run more boost out of the ATI sc kit when i becomes available to the general public.

just getting the ssm powerpak will get you 70 flywheel hp increase if you have it tuned as well. before you do that though, get some 1.9:1 roller rockers from www.3800performance.com. They work w/ the stock camshaft, and if you ever wanted to get a new canshaft, you'd have to tell the cam manufacturer that you will be running 1.9:1 rockers on it so they size it correctly. the roller rockers will get you a good 10-20 hp if you already have your intake and exhaust done. Do this later though, because it is 500 bucks for the kit.

[ May 29, 2002: Message edited by: Patrick Javert ]</p>

[wolf]

<blockquote>quote:</font><hr>Originally posted by navyblue2000:
what's the formula for how much more compression equals how much more hp? ...<hr></blockquote>

4% more hp per point of compression