Thread: safest c.r.

whats the safest c.r. for a first gen sr20ve motor on 90 octane fuel. how do u calculate the c.r. of a motor......thanx

The safest c.r. would be 1.1:1. I guarantee you will not detonate. (I was gonna put 1:1 but then it would technically not be a compression ratio. DOH!)

The lower the safer, and the lower the less power. Generally you want to go as high as possible while avoiding pre-ignition. Turbo engines have lower compression because they are more likely to knock at higher compression than an N/A engine.

C.R. = (Vd + Vc)/Vc

Vd = volume swept by piston
Vc = clearance volume

Lol I know you are joking but I seriously do not think your engine would run at that ratio

12 is the highest you can go on pump gas. but for reliability just do 11-11.5:1