it's a re-re build
 

There is a lesson to be learned here.

I recently purchased a rx8 with low compression for my winter project while my business is slow. The previous owner had just "rebuilt" the motor and failed. He said a rotor seal broke. The PO replaced the damaged parts, replaced seals, and gaskets. The engine was hard to start cold and would not start warm. The PO had it compression tested at the dealer and it failed. He decided to cut his losses and sold it to me. Since the engine was fubar after the rebuild no miles were put on it, maybe a couple hundred at the most.

I pulled the motor and disassembled it. this is what I found. waterpump was loose, 2/3 oil pan bolts finger tight, flywheel gland nut less than 50 ft lbs torque, front e shaft bolt less than 20 ft lbs torque, engine assembly bolts some tight others not so much. rtv and hylomar all over in huge quantities(some of it squished into the rotor housings), the one rotor housing is junk. I did find some good stuff, new light weight flywheel, clutch, pressure plate, no carbon deposits, new seals, bearings look great as well as the e shaft, the other housing is excellent, irons are usable as is but would benefit from lapping.

If the PO had replaced the one housing, used less rvt and hylomar, and properly torque all of the fasteners this motor would be running fine.

Yesterday I made this rebuild more questionable. I picked up a used engine from craigslist for less than the cost of a set of apex seals. The used engine was described as "running" when removed. miles unknown. I did a cold compression test on the engine stand. 100-110 psi across all rotor faces on both rotors at about 200 rpm.

So I have come to a fork in this road. Do I install the mystery engine which "seems" OK or rebuild the other motor at a much higher expense?

I'd put in the mystery engine.....and rebuild the other one for a spare or to sell :)

Im with dan.

I would try it also, what do you have to lose except time installing the engine. Worst case is either don't run or you drive it till it dies, then you have some time to rebuild the botched rebuild. I bought a mystery engine off eBay for my 7 and it lasted 4 years @ 50k miles for $650. Broken apex seal finally took it out along with housing was trashed.
Go for it and good luck!

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Hmmm.... well I think I'll drop in the mystery motor. I am going to clean up a few things and swap out the ancillary bits. In a few days I should i have it in and hopefully running.
You got to love craigslist, 1% gold, 99% sh!t. I just hope this engine is that 1%.

A suggestion, not sure if it will help, but I would squirt some oil into the chambers and turn it over to spread it around before starting it up. I had one of these that tested really well on the ground, and started right up when installed, but eventually died badly. I really think any oil was gone from the side seals after sitting so long and they just ground down. At idle it takes the OMP a long time to get oil through the lines and into the engine.

Ok, I install the mystery motor and it wouldn't start. I have spark. I have fuel pressure. The injectors are not squirting. I pulled a vacuum tube squirted some ether in and it fired right up then died after burning off the ether. I am at a loss as to why fuel wont squirt. I may try the injectors from my old motor tomorrow. Maybe the mystery motor injectors are plugged. Any body have any insight?

Swapped injectors and it started right up. So now I have a running cheapo craigslist motor. After fully warming it up, I performed multiple key start sequences to verify no issues with hot starts.

Nice.....always good when things behave ;)

mystery engine update.
After nearly 3 years my super cheap craigslist engine is still running great. I did have a couple shuttle valve solenoids fail(and replaced), but other than that no other issues.
I have driven faster cars, and a few better handling cars, but none that make driving as pleasurable as the rx8.

Now that I updated everyone that this thing still is running great, I will probably need to order a reman. Murphy's law dictates the engine will catastrophically fail during my next drive, since everything is going great.

^This man knows the only time thread revivals are acceptable
Now for the $1,000,000 question.... can you pick out a craigslist engine like that for my 8? Im already troubled with a dreaded 3-4 second hot start.