godesshunter

So its pretty common knowledge at this point to do a compression test before purchasing an RX7

I hear a lot of hype about compression testing at a certain RPM. And how that can be a determining factor of pass or fail.

I read the sticky for Bonsai Racing compression test procedure and it didn't say anything about RPM. Is this an important factor to consider? And if so what RPM should the test be performed at? And finally if so does the starter motor alone achieve this desired rpm or is there a secret step to take.
Thanks

RotaryRocket88

iTrader: (7)

Standard specs are at 250 RPM, which is what the starter will crank at with a fully charged battery. That's it.

godesshunter

Ok that easy enough. Thanks.

misterstyx69

iTrader: (142)

make sure that you have the throttle wide open to get a more accurate reading.
If the throttle is at idle(closed) it will effect the reading by a couple Psi.

godesshunter

Ok. Good to know thanks. Wouldn't leaving the remaining plugs in also affect results? Should all the plugs be out or just the one being tested at the time?

dgeesaman

iTrader: (7)

Download one of the FSM's and it will detail the procedure including RPM compensation.

turnbullFC

iTrader: (1)

what is the compression supposed to be at on a s5 motor?

Memphis

The '93 FD shop manual says 690 kPa {7.0 kgf/cm2, 100 psi} minimum @ 250 RPM. Differential limit of chambers is 150 kPa {1.5 kgf/cm2, 21 psi} @ 250 RPM.

S5 may vary a bit, but should be close.