i have a 1st gen that i put a street ported motor out of a 87 gxl. i am running a 51mm weber and racing beat race headers. 4 days ago an apex seal rolled trashing the rear rotor and housing. so know i have a clean sheet to work with and a good excuse to build a bad *** motor. i was wondering which 13b or what combination of motors is the best to run? i am not going to run forced induction just strait up motor. it is no problem to tear down a motor so don't worry about that. thanks for the help!

 

I would say RE housings with N/A S5 rotors

but if you're doing radical porting anyways....I'd just get an S5 shortblock, then p-port that monstah!!

 

RE housings? where would the exhaust go? I was thinking the opposite, S5 housings and irons with RE 10:1 comp rotors and e-shaft. the rotors will need to be milled to accept the stronger earlier gen apex seals to avoid flex over the exhaust ports tho

 

out the exhaust port? what do you mean?

Didn't know the RE had 10:1's.....that would work well/better than the S5's. Even renesis rotors (???11.5:1???) would be a thought, although the milling would be necessary because of the thinner apex seals (due to having side exhaust ports).

 

I think he has RE confused with Renesis which would explain the question of exhaust ports. RE = 13B-RE(w)Cosmo 2 rotor engine.

 

I think he's talking about the 13BRE, the engine from the Cosmo, not the Renesis from the RX-8. And I think the 13BRE ran 9:1 rotors like the 3rd gens, the Renesis runs 10:1.

I think he's saying use the RE housings because you then don't have to worry about removing the exhaust diffuser that's in the N/A engines. But I think you can use any housing from a turbo engine if that's your goal, just as long as it's a nice clean piece that's in spec.

Another thing to look into is beveling your rotors.

 

right, i did have that mixed up. been a long day at work, and ive only been here 3 1/2 hours. sorry for the confusion, i was thinking he was recommending the renesis housings. Ok, cleared up :-)

 

Also, the intake ports are initally larger.

 

I was just talking about the rotor housings not the side housings, if you want to go 4 port and loss what little low end torque there is, then sure.

 

The 13B RE rotor housing have strange exhaust sleeves in them too, not like the T2 or REW ones. I dont think you would want those either.

 

well i think i'm pretty much confused now. i think what you are saying is that i
should use tII rotor housings and the rotors from a s5 motor correct? i am thinking of doing some kind of port maybe a bridge port not sure on that. i have some irons from a 85 gsl-se (is this the 13b-re you are talking about?). i an kind of shooting for the 250hp mark just to give you an idea of what i need. i have several motors 1 gsl-se motor / 1 12a motor / and the 87 gxl motor / if i need to get any thing else it will not be a problem.

 

well I was suggesting cosmo RE housings, not GSL SE housings. Entirely different.

For 250 wheel, a fully bridged S5 N/A shortblock will get there with ITB's and good tuning. PM 01racing, he's a local guy from Scarbourough Mazda who runs a fully bridged S5 on the track, he's making close to 280.

 

what years is an s5 motor in? the motor i am going to get is out of a 91. is this the motor i need?

 

89-91..........you got er!

 

You don't want the housings from a 13B RE cosmo twin turbo motor. Well, the housings are fine just they have diffusers in them. If you are willing to swap the diffusers for T2 or FD ones(not an easy task) then you can use any good housings from any 13B motor just try to stick with 2 of the same. Another option if you are budget is to grind out the N/A diffusers, this is not as hard as people say.

If you are bridgeporting, most people don't waste their time with 6 port irons(like the GSL-SE, or any other Na FC iron). I'm not sure on what 01racing's exact engine specs are but I would be surprised if they were bridgeported 6 port irons.

 

well, a pp WILL get you in the hp range you want. i wonder what a pp will put down with renesis rotors? one more thing, a na 20b should put a BIG smile on your face, but a sad face on your walet lol

 

i am on a budget so a 20b is out. if i want to bridgeport what irons should i get? can you use the irons from a 12a to make it a 4 port or do i need to get 13b 4 port
irons? i am sorry i am asking all these questions i just want to build this motor once. i have been thinking of doing a pp port. and would like any help! thanks

 

Well for a full bridge you could use 4 port TII irons or 6 port ones.........most people do a bridge on 4ports for simplicity.

If you're thinking of doing a P port, use 4 port irons......less ports to fill :biggirn: