Peacedog94

Hi all,

A basic question. Is it possible to use late model hi compression (9.7) or renisis rotors in GSL-SE rotor housings?
If so, other than having the assembly dynamically balanced, to include flywheel and counter-weight, what else needs to be done to make it work properly?
Thanks,
Peacedog

slo

iTrader: (1)

no need to balance if you use the rotating assembly all from the same engine, with the exception of the e shaft. IE 9.7 rotors, with 9.7 counterweitghts and auto counterweight or flywheel. Best combo IMO would be 9.7 rotors (+ counterweights and flywheel) with rx8 gears, bearings and eshaft. The Rx8 rotors don't make more power and the apex and side seals will likley wear out much faster, and not be as strong in general, especially the apex seal which isn't designed to pass over a periferal exhaust port.

j9fd3s

iTrader: (3)

i did it, i took the whole rotating assembly from an 89-91 engine, and put it in the gsl-se housings. i gather the rotors and housings are slightly differently shaped, and its not a good idea, but my engine is still running and it gets beat on really hard.

also the stock ports on the gsl-se engine are small/not so great. the previous setup in the car was just a stock s4 motor, and it made more power on the butt dyno

Peacedog94

Fellas,
Thanks for the info. I was going through an old storage locker of mine and found a really cherry set of GSL-SE housings (the tags on them say '84 anyway). The really funny part is that the last time I took an engine apart was 1989. It just got me to thinking about maybe putting together another FB after an extended (about 8 years) break in owning an RX7.
Regards,
Peacedog

BLUE TII

iTrader: (9)

I have read about the slightly different shaped older housings and I have read of people laying one rotor housing directly over the other and reporting no difference.

I believe the source of this information RB says you should not mix pre and post '86 rotors and housings due to their slightly different geometry.

Could they actually be reffering to the spark plug and rotor depression geometry and people misunderstand?

diabolical1

iTrader: (3)

for what it's worth, whatever source i read when i became aware of the differences in housings specifically quoted a difference in the peritrochoid. i remember that because that was when i learned what a peritrochoid was. it was a long time ago though, so i can't remember, it may have been RB, but don't hold me to that.

however, i haven't heard anyone reporting problems when they mix the rotors and housings, either way forward or backward, so i must admit that i don't feel as leary as i once did about trying it myself.

slo

iTrader: (1)

There is no difference in the peritrochoid shape or dimentions. The construction is somehwhat different, the location of spark plug holes is slightly different, and the biggest thing, the side seal grooves are in the rotor housings of the pre 86 engines and the side housings of the post 86 engines. That was a better design IMO, and the previous engines seem less likley to be damaged by overheating, and corrosion. The Rx8 went back to the side seal on the trochoid designed.

Peacedog94

Hi guys,
Just to clarify, so the water seal on the RX-8 engines is now back on the rotor housing? If so, does this mean that you could use the new RX-8 side housings and rotor assemply with pre-86 rotor housings? I understand that this would result in multiple exhaust ports (both from the side housings and rotor housings). While this might be difficult from an exhaust header perspective, would this result in some kind of power gain due to all of the exhaust venting will much greater efficiency (assuming a custom exhaust could be made to fit) much akin to a really large exhaust porting job? If not, could the side exhaust ports in the side housings be blocked so as to use the RX-8 high compression rotors?
Just curious,
Peacedog

slo

iTrader: (1)

I would think this would be a bad idea, I think it would make for a peaky engine thats not all that powerfull in the first place. You can already use the rx8 rotors in any 13b, IMO thats also a bad idea, more expensive, no more hp. And finaly, just because the seals are in the same place dosent mean they compatible (they might be, might not)

j9fd3s

iTrader: (3)

sweet! i made it like 3 months without a 1st gen, been driving em since 94....

j9fd3s

iTrader: (3)

ive done that too and not seen a difference, i built the motor even! and have had no troubles. i dunno. might be the rotors are slightly different

slo

iTrader: (1)

Yes but not really where is counts, different apex seal width, different weight, different compressions, tip to tip dimentions and shape of the curve between apexes is the same.