compression ratio vs torque & HP

b9folk_old · July 11, 2007 at 10:51 AM

I'm not an experienced car guy and don't know anything about some aspects of high-powered engines. I've been reading some old posts about fuel octane and compression ratios, which make sense to me. It sounds like some cars are ok with today's premium, others are not.

But - How does a higher compression ratio affect the torque & horsepower curves? If I purposely lower my compression ratio to avoid predetonation, does that lower the entire curve or does it shift the peak power point to a lower RPM?

Beagle1_old · July 12, 2007 at 9:23 AM

When you lower effective compression ratio you lower power across the whole range by lower cylinder pressure. Now this is given no other changes take place, like a camshaft or forced induction.

The combination of parts: Mainly the cam, but the heads, intake, exhaust, even connecting rod length, etc., determine the location of peak HP and Torque.

map351_old · July 17, 2007 at 5:21 AM

You can run high compression engines today you need to control the air/fuel ratio & timing.

Participate now!