Compression on the 3rd gen 7
 

What's the compression on our cars (FD, US spec engine)? I know it's 9.0 now in Japan with stronger apex seals and more boost (damn!).

Thanks

-joe

is it the same?!?!?

thanks

-Joe

i think the 'standard' is like 7-9 though thats the source of some debate, and there are different ways/units to measure it with...

Do you mean compression ratio or the measure of compression to see if the engine is still in good working order?

There is a chart in the shop manual the shows the acceptable compression of the engine versus engine rpm....

It is roughly 7.0 kgf/cm^2 @ 250 rpm.

Patrick

Don't mix up compression ratio and compression pressure. The compression ratio is 9.0/1, that is just a static value that relates the ratio of the volume of the combustion chamber between TDC and BDC. The compression pressure is spec'd at 8.5kg/cm^2 or 120psi from the factory, with a minimum of 7.0kg/cm^2 or 100psi, with a maximum difference of 1.5kg/cm^2 or 21psi between the chambers. The minimum was eventually lowered to 6.0kg/cm^2 or 85psi. I've only seen a few people actually test in the 8s, with most being in the 7s or 6s however.