Compression testing
 

Alright, so I'm starting to go more in depth about compression tests on a 7, and I'm wondering what a "good" "bad" and "excellent" range are for compression numbers. If I remember right, 120 is brand new, and 80 is about shot. A couple of cars I've been told have 85 compression, and the mechanic has said that the seals are worn, but would last another 5 years if it's driven lightly. I want a 7 that I can build up and make fast, but I'm thinking if I give a rotary engine with that crappy of seals some abuse, it's gonna blow pretty quickly. So what are your guy's thoughts here? Is this car gonna hold up?

Personally IMO it goes like this

120 -new

100 -excellent

80 - Worn

70-60 - on the verge


If you want a seven that you want to 'build up fast' my advice to you is buy a blown engine and get it rebuilt. If you want to really top it off, you can buy new housings, or to give yourself the luxury of a brand new engine, buy it all. If you do that, your looking at 4-5grand US im sure ;) aka not worth it.

Personally, if Im getting a rebuild, I'll save for it and get myself some new FD housings. Machine the rest if its still good and have it rebuilt by dan or kevin.
This just gaurentee's that your going to have an engine thats going to live a long while if you take care of it.

Rtfm

I'd say anything below 90 psi is getting sketchy...

Buying a new engine is definitely outta the question. Any clue on how hard it would be to replace the seals on the engine if it turns out that's all that's wrong? Definitely good to know what I'd be looking at on engine life with that car. 85 compression definitely ain't gonna get me many runs down the track, or even some miles to put on the car. How much do rebuilt engines usually cost for the engine and labor? How hard is it to put a rebuilt engine in yourself? Thanks for the info guys.

Any help here guys?

Do a search for rebuild, and check the archives for rebuild threads. That should answer your second question. Your first question has already been answered.

Shops around the DFW area charge around 4 grand. They replace most everything.

MAN nothin ever changes in HI-PERFORMANCE vehicles, how fast do you want to go, how much do you want to spend, money cures all man related problems. just a note.

Just so you know, a lower compression engine can survive for a while. My 88 TII had 75ish psi on the rear rotor, 80psi on the front at 174,500miles. Now I'm almost to 178,000 and it still pulls hard.

I will be rebuilding it over the next couple weeks, however.

Alright, thanks for the information guys. I'm gonna start looking into the rebuilding for the engine.