Does anyone know how much it noramally costs to have a shop run a compression test, i was told i should do one before running nitrous.
thanks for any replies.

 

Save yourself some money and buy a compression tester at Sears.

 

How much do they cost? and how do you do it?

 

~$40, I think. No more than that. It is very easy to do a compression test. If you get a tester, you can get help here on how to use it.

 

Its cheep and very easy to do, and yes you should do this before adding naaawwwz to see if your leaking pressure anywhere... you may want to do a leak down test but not really necessary if you get good #'s with your compression.

 

the compression tester i bought at sears cost me about 28 dollars... if you can change your own spark plugs, you can do a compression test...

 

Basically you get the tester, it has one end that has threads like a spark plug and the other has a guage. Pull your spak plugs out, screw in the guage into one of the holes where a spark plug was, start cranking the motor(its best for someone to watch the guage and ensure you cranked long enough) the guage will stay at peak pressure and tell you whats the compression results. You repeat this for each cylinder...the last time I did mine I had numbers of 210, 200, 200, 200. They aren't going to be perfect across the board but if you have an oddball that is low, I wouldn't squeeze on that motor, its already lossing compression either due to piston rings or valve seals.

 

so what would be some good numbers to use zex 55 shot because i have this kit on the way and i didnt do a compression test yet and if the numbers are to low what could i do so i can run nitrous

 

Make sure the numbers are consistent, thats the most important thing. No more than 10-15% difference i think. Usually numbers are around 200, but consistency is the most important thing.

You can find cheapo testers at autozone for around $20 and its really easy to do. Its a good time to change your plugs too, if you plan on doing this, since you're running nitrous.

 

all my numbers were around 210 with a 2psi difference (93' H23). Also you want to put a cap full of oil in each cylinder and do the test again just to see how much pressure your actully losing (mine all jumped to about 250psi after this)

Oh ya dont forget to pull the fuse for the ECU before testing

 

I did a compression test last night and I got 175-180 on all 4 cyls. Is this very low? It's a 92 H23A1.

 

Those numbers should be fine.

I never pull my ECU fuse, i just ground the distributor so there is no spark.