Can someone tell me what the compression on the USDM ITR B18C5 should be? Not the ratio, but the PSI. From what I understand 135+ is good and less than 85 psi is really bad in general, but I'm not sure if it's different for our engines

 

i wouldnt really want anything less than 190 psi. if its not burning any fluids and runs fine id be ok with 190 something. on a perfect motor im sure it would be in the 220 range give or take a bit. 135 has problems.

dont forget proper procedure for the comp test

up to operating temp
disconnect injectors
disconnect distributor
6 cranks, with the throttle wide open

 

thanks

 

I wouldn't focus too much on individual numbers. Each compression tester is different. I would focus on the consistent numbers across all four cylinders.

 

Thanks that's really good advice

 

Compression testers and the way the test is carried out differs.

The way I test:

-Cold engine
-Pull the PGM-FI fuse so that the injectors and spark turn off
-Hold throttle open
-Crank till needle stops (try for consistent amount of cranks per cylinder)

I got 220psi with my tester on my JDM B18C (96 spec) engine.
270psi on my JDM B18C (98 spec) with head work

Other relevant cars for reference

240Psi on my stock F20C S2000.
210Psi on my GSR's original B18C1
210Psi on my EM1's original B16A2

I'm fairly sure my tester reads high. But I was looking for consistency and comparison between cars. For example...if my (10.5:1 cr?) B18C was showing a higher Psi than my (10:1 CR) B16A2, which I knew was in good shape...then I was winning.

 

Compression tests are supposed to be done on a warm engine. Rings need to be expanded to get an accurate reading.

My usdm type r tests at 245-250 on all 4 cylinders.