compression on a rotary?

[BBMac]

hopefully you rotor heads out ther can confirm and answer these questions.

1. the compression reading on a 12a should be inbetween 80-110 psi correct? 80 being low.

2. will a leak down test gauge my compression accurately? or is there a formula I can use with a regular compression tester?(like add or minus 20% of what was measured)

Any help would be great.

[Alpine Autowerks]

a compression tester will show the pressure of the BEST chamber in each rotor housing , you need a pressure transducer and a plotter to record all 3.

[BBMac]

yeah ok that makes perfect sense now. no need for anyone else to answer unless they feel compelled. I can get access to all these so that makes life easy.
Thanks a lot alpine
Brydon

[SwitchBlade]

Just get a compression tester and hold down the release valve and read the compression readings. ;)

[BBMac]

didn't I tell you that at work today??????

[SwitchBlade]

ya :poosie:

[rx7_turbo2]

Originally posted by SwitchBlade
Just get a compression tester and hold down the release valve and read the compression readings. ;)

Bingo. It's no nearly as accurate, and it's little tougher to do with only one person, but that's the way to do it.

The compression issue has been debated time and time again on rx7club. Without using the proper comp tester it's hard to get a diffinative number. The regular tester will give you a very good idea of what's going on though. The key is to look for 3 even bounces of the needle.

[962 kid]

or, you could just use a pressure transducer and a plotter, with much better results

[BBMac]

use a transducer and a plotter? I think that was used in the first response

[962 kid]

Originally posted by BBMac
use a transducer and a plotter? I think that was used in the first response

I know, I just meant why compromise by holding the valve on a regular tester open and guess what it says when you could do it the proper way

[Maxt]

If you take out the schraeder valve on the inlet of a standard compression testor, it will do what you need it to do.... Just make sure you pull the egi fuse or in carb case the coil wire, make sure the battery is right up, hold the throttle wide open and let it crank, you need 3 even pulses over 80, if you don't have that you don't have much of a motor...
That factory tester uses a transducer to give you its reading, while nice to have, not available at Canadian tire either...Maxt