Hi guys,

I'm currently looking at buying a stock standard unmolested '99 FD and the seller has done a compression test on it

I have searched on google but I keep getting mixed answers some says 85psi is minimum and some says 100psi is minimum

So I thought I would post here and get some you guys opinions since I'm new to rotary.

The seller is a car dealer that specialist in RX7 so I assumed he knows how to do compression test properly

 

Those numbers are incredible... I would say its healthy.

 

The 21psi difference between the front and rear rotor doesnt bother you ?

 

our dumb american book only goes to 1994, if anything 99 would be slightly tighter

 

not at all... not every engine is going to be uniform between front and rear. Compression is good, I would call it a healthy motor.

 

I’d be happy with those numbers If I did a test

 

The 21 psi difference between rotors might bother my OCD nature a bit, but that's a perfectly acceptable motor that you should get lots of miles out of. Both rotors meet Mazda's specs for minimum compression, and the face-to-face differences in compression for each rotor are also well within spec.

 

I'll chime in and say that a while not a deal breaker that large compression discrepancy front to rear is indicative of one of two things: 1. The engine has been rebuilt and one of the rotor housings (or potentially irons, but my bet is usually rotor housing) has been replaced, hence fantastic numbers. Your sealing members (apex, side, corner seals) and springs are good, but the material they're sealing against is still good on both, but one is great. And 2. Whoever rebuilt the engine is good at their job and you're probably built with .002-.003 thou side seal clearance (where great cranking compression numbers tend to come from).

So no, don't shy away, but do go in armed with a bit of knowledge when you speak to whomever you need to about it.

 

Hey guys just wanna say thanks to everyone that commented

I bite the bullet bought the car.

Is it true that rotary engine needs to be driven hard every once awhile to avoid carbon build-up ?

Here are pics of my new toy 100% factory standard apart from the optional BBS wheels from an RZ I believe ?

 

that and it opens the metering pump up all the way, oh and its fun