I just tested my compression with the $25 compression tester they sell at Autozone.
#1 - 260
#2 - 270
#3 - 280
#4 - 290

I'm running a B18C1 w/p73 pistons. I haven't really heard of anyone having compression this high before. I saw on c-speed racing's compression test how-to they show a car running 11.6:1cr and hitting 250. According to c-speed racing's compression calculator my car should theoretically have 10.8:1cr according to that calculator, so Shouldn't my numbers be lower than the 11.6:1cr they tested? Are my compression test numbers too high? Is that even possible? Anyone have any thoughts or input? I just rebuilt my motor about 7,000 miles ago, if it has any bearing on anything. Thanks in advance.

 

are you sure you did the compression test correctly?

you have a 30PSI diffrence between #1 and #4 which isnt good.......

it could be possible the guage is incorrect but it also matters how many times you crank the engine over.......

what procedure did you do when doing the compression test?

 

 

doesnt sound right, just make sure you are testing your compression in the proper manner. sounds a little high. Dont think p73 pistons would cause those kinds of readings.

 

did you get the head milled also?

 

doesn't look to good. You should retest..

 

I used the directions from c-speed racing. Pulled the plugs, pulled the fuse, cranked the motor over 5 times. From what I've heard previously, you're ok as long as you're within 10% min and max, so I'm about at the max. The head wasn't milled (as far as I know), but it was used so I suppose there's always a chance.

 

I would think that you could very well be running ~11.6:1 with domed P73 pistons with a P72 (GSR) head.