I've done searching on the boards and couldn't find any information on race built engines. Does anyone sell something like this? I know that there are builders like Mazdatrix or Pineapple racing, but do they sell a ready to drop in engine? I currently am in the process of upgrading my FD for the track (going with a small - mid sized turbo) and would like a balanced motor that's more responsive. I got my current motor (reman with 25K miles on it) compression tested at Lucky 7 and based on what I was told I'm getting numbers for both rotors from 7.5-7.9 which is pretty low. I want to make sure I've got a strong enough motor before I do any major upgrades. Any thoughts?

Thanks

 

Lucky 7 told you that 7.5-7.9 is bad? I think those numbers are actually pretty good, thats between 106-112psi. Many people run motors to 85-90 psi of compression before even thinking of rebuilding. I have heard that lucky 7 was a good reputable shop but I would be questioning the honesty of anyone trying to sell a rebuild on an engine with 100+ psi compression on all faces, assuming no other issues.

 

Also, to answer your question try http://rotaryrebuildstore.com/pricing.php for pre built engines with no core charge.

 

I might be confused, but he was saying that 7.5 is the spec lower limit for the engines. Is this correct? Thanks for the link btw.

 

Page C-10 in the workshop manual has the specs. 7.0 is minimum. There is however correction factors for altitude and cranking speed, if you were seeing cranking speeds at or above 280rpm that would put you around 7.5 with corrections. Im not sure how common that is tho, on all my comp tests I come in on the low side of the cranking speed chart even with a full charge and a battery charger hooked up.

 

Most shops that offer engine rebuilds offer services from dropping the car off and they do everything and you pick it up, to you pull it and ship it. They rebuild it and you reinstall it. So I guess the answer to your question above is yes, the engine is ready to go once you get it back. I will definately say you should send your motor to a very reputable builder. Pineapple, CPR, Rich and Ihor (thier company name escapes me at the moment), or the like. Assembly and clearances are very important in building a reliable engine.

As to the health and useability of your current engine. It sounds like the numbers you posted (as long as those numbers are consistent across all three faces of each rotor respectively) your compression is fine. Not great, but certainly not bad. The condition of the other engine components will be determined by your engine builder when they begin clearancing it all after disassembly.

 

I'll be picking my car up tomorrow so hopefully I'll have the exact numbers so I can post them then. Thanks for the info btw.

It sounds like I'll be safe as long as I'm conservative with my tuning. I'll probably have a better picture when I post the exact results as I only heard it off the phone with the mechanic.

 

Based solely on what you have posted so far, it sounds like your motor is fine for now at least.

Your choice of turbo and manifold will have a much bigger effect on response than rebuilding an engine that is still making solid compression. And FYI big porting isn't going to make it more "responsive" (people have different definitions for that) any more than putting in a high lift/long duration cam(s) gives piston engines more response. Check this thread out about a tracked FD running a responsive turbo setup with stock ports https://www.rx7club.com/single-turbo-rx-7s-23/autox-fd-dyno-956766/

 

I couldn't agree more about the porting. I'm looking really to run a small to mid sized single turbo (to reduce complexity and heat) that makes about the same power as the twins. As far as the motor is concerned, I was more looking at aluminum housings, balanced rotors, race tolerances, lightened eccentric shaft, etc. for a high rev capable engine. That way the motor will be more built proof, and when I get a new transmission, say a 6 speed close ratio, I can then open the rev limiter and take advantage of the high revs. Of course like you said, it's probably really not necessary at this point.

 

Ok, so I got my car back from lucky 7 and it looks like I heard wrong over the phone . Seems like my compression IS really low (at least on the front rotor) . Here are the numbers:

Front:86 86 73
Rear: 86 87 87

Is there anything I can do to raise those outside rebuilding? Perhaps cleaning? I heard something about running steam or something of the like. Let me know what you guys think.