What's normal compression readings for a S4 TII????
 

I am testing mine with a piece-o-crap compression tester but want to know what the ballpark readings should be.

bump

As a rule of the thumb you should get no less than 80psi(3 even bounces) for both front and rear rotors with a maximum difference of 20psi between the front and rear rotor.
That 80 psi is a rough factory service number but you also have to account for cranking speed and atmostperic pressure ie altitude change

Hmmm, It is hard to tell but I seem to get 90 (maybe a little more), with the release plugged and 3 even bounces around 70-80 or so with the relaese held in so that it can bounce. This engine has been out of service a while (JSpec), I am cranking it with a portable jumper box, and the engine is drained of oil if that makes a difference. This seems to be a good motor since the readings I get are most importantly, pretty close to each other (within 10psi). But as we know you can't really tell until you turn the key and start her up. If anyone else has any feelings (from REAL experience only please) let me know.

I called rx7.com a few years ago and asked the same question. I belive it was Rocky, that said not to worry as much about the peak, as there are so many varibles, but make sure you get even bounces.

IMO getting 80-90psi out of a J-spec sounds nice. I bet it will turn out to be a real strong motor

Oops double post

It seems real even and consistant, and I always remember the "experts" in pistons and rotaries saying that is the biggest indicator of problems. I feel confident enough that I started yanking my NA out motor tonight.

Thanks for the reply,
John

Err.. in your post you said you were holding the pressure release valve. Did you remove the one-way check valve at the tip of hose.. you can remove that checkvave with either a valve stem remover or a pair of needle nosed pliers and screwing it out. From what you have posted it seems that the engine is fine.
However, I think you should redo the test w/o the one-way check valve to get a better reading.

I don't recommend cranking on a "dry" motor, but with oil pressure you should get higher readings as the oil will help the apex seals do it's job.

This one uses a push button rather than a valve, if you hold the button in it just pulses.

NA is now out and the TII is going in tomorrow

It's ALIVE!!!!!
 

Update: after almost a week of family obligations I finally got it in and started. The motor is strong and seems to not smoke at all. Another good Jspec drop in story. I am lovin it.

:D

Congrats on the TII swap, now go enjoy your TII vert. By far the best mod I ever did, my vert is a blast to drive now.

I created a leak in my UIM from when I reinstalled it after wiring in my harness but tomorrow I should have it all straightened out. BTW how did you do the drivetrain? I was lucky enough to get a TII trans with mine so I had a custom driveshaft made up using the front yoke of an auto with my NA shaft and rear yoke. It cost me $155 and now it bolts up like a OEM part and I have both new u-joints.

I bet it does awesome 1 tire burnouts :D

LOL, yeah I guess it will. But one tire burnouts are so ghay.