I have a 94 GSR with 98k miles. compression is 192 to 199 with engine warm and throttle open. Leak down is 2% per cylinder. The shop manual says compression new should be 270 psi. Minimum acceptable is 140. My question is how do these nunmbers look and how much power am I losing being at about 200 pounds versus 270? this car is now used in SCCA road racing so I need all the power I can get. anyone got good idea how much more power the higher compression will provide.????

 

Your numbers are fine. Within 10% is good. It all depends on the tool you use, some give higher numbers than others. 270 seems unreal

 

Your compression numbers are pretty typical, and your leakdown is exceptionally good for that kind of mileage and usage.

I compression tested to 210 to 220 for all four...some carbon build-up. It was mostly built up on the exhaust valve faces.

Get your car on the dyno and see how you compare to similar GS-R's.

A friend's ITR compression tested (cold) to b/w 190 and 195, but dyno'd to a peak of 165whp and 119lb*ft with just a Spoon foam filter.

You might not be as far off as you think.

 

Since we are on the topic of Compression here. I did a search, and came across a thread about someone doing a compression test, which resulted in 3 of the 4 cylinders had compression of 190 and one of the cylinders had a compression of 185, then performed a valve adjustment and it brought the low cylinders compression [185] up to 190, so he had the same compression acorss the board on all 4 cylinders.

Could one assume that if compression numbers are low that a vavle adjustment should be done or is required?

Also, is that a good way to determine that a valve adjustemnt is needed?




[Modified by IntegraGSR23, 10:44 AM 10/3/2002]