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View Full Version : Strange compression result sr20det RWD 5-speed


Kingtal0n
05-20-2016, 09:32 PM
Had a very strange result on a friends car
cylinder #1 through 4
dry test (no oil)

140
151
140
151

IS there something obvious causing this? I seem to recall seeing this before.
engine is mostly stock redtop, but i know somebody changed the cams.
something about valve seals? or maybe we need to degree his cam...

supersayianjim
05-21-2016, 12:30 PM
bump for an answer??

Kingtal0n
05-21-2016, 07:55 PM
Well. It is a friends car, he wants to go forward with the tuning despite the strange readings. I am not sure I can convince him to open the cover and degree the cams. I am still waiting for him to tell me if they did the valve seals while in there. I think we might need a leakdown test next step, but neither of us has an air compressor handy. Hmm. I do but in miami so... gota think about this. I just seem to recall from 5 years ago a similar thread, and they found something like this...

zombiewolf513
05-21-2016, 09:14 PM
Is that cylinder one through four, or four readings on one cylinder?

cotbu
05-21-2016, 10:05 PM
If you did both dry and wet like you should, you would at least have narrowed it down to Rings or valves. You could even make it worse or better? By finding a 5psi increase from the wet test. Then where's the other 5 or 6psi???

I don't know if you performed the wet test or if you had all the plugs out, but I guess you searching for that related post

You have to verify timing if you are going to tune, and if you tune with a question on your mind, you're just like the rest of the cats in this game.

Kingtal0n
05-22-2016, 06:34 PM
next time i see the car i will do the oil/ring test. I Dont think its the rings though. Very unlikely both cylinders have exactly 10psi worth of ring "loss" perfectly like that, its just very strange if that were true. I think it more likely that something with the valves/cams.

and fwiw I never had any reason to degree wheel any camshaft in an sr20det before. Must have tuned 50 to 80 of these engines. It usually isn't an issue, you get a tomei cam, install a tomei cam, and go to town right away.