I have a 'C'-series 20B that I'm going to dump into my FD over the next few months. Ideally I want to run it with stock internals to begin with in order to iron out any problems that may arise with the installation before tearing it down and porting/pinning etc later on.

I will be testing it with a Comp07 compression tester next week.

Question: What do people view as good/bad/excellent compression? Obviously I'll need to make a call as to whether or not I NEED to rebuild now or later. The inconvenience/time/cost of doing it later isnt material.

Thnx,
R.

 

Internally a 20b and a 13b are the same. So whatever compression readings you get, compare them to the good readings of a 13b.

 

Yeah, I realise this - so what is 'gospel' regarding compression results on the 13B and 20B units i.e. when is it not worth NOT rebuilding??

 

I'm pretty sure 120psi is about the top, so you can work backward. It would really vary according to opinion but I would say around 90 for a floor in my book.

Then again, you are talking about a 20B where higher standards would be applied. 20B = out of my league.

The guy with this car, 13BT, calls the rear "weak".

Cheers

 

since it has the same compression ratio as any other 89 and later turbo rotary use those specs

mike

 

The rear rotor in that compression test is shot. I would say he has taken the end off one of the apex seals - definatly rebuild time for that one!

As for the question, I think anything below 90 (hot) is getting a bit tired. Anything uneven , as in the photo, its time to rebuild.

 

That guy's been driving/autox'g that engine for quite a while, like 6 months or more I think.

 

As long as there all even and about 100 psi you will be ok.

Chris

 

Since when is a rotary engine not worth rebuilding? The only time I can think of when it's not worth rebuilding is if you have some catastrophic failure that nukes all your housings and rotors. There is always some value in keeping individual housings in any case.

 

Sorry HyperRex, you misunderstand me;

"when is it not worth NOT rebuilding??"

I meant (compression-wise) when isnt it worth sticking the motor back in the car without rebuilding it first?

Think I have my answer any way. All 3 rotors were around 110 psi :-)

Thnx all,
R.

 

haha ok sorry. The double negative really screwed me up.

 

LOL, just chucked it in there to confuse all those of you not NOT of an north american persuasion ;-)