Hey just want to hear some input on this setup.. either S4 9.4:1 or S5 9.7:1

Since I need to replace a S5 TII rotor, just thinking about going with the higher compression NA rotors with a single hybrid turbo setup (to4b compressor http://photos-b.ak.fbcdn.net/hphotos..._5417092_a.jpg ) Eventually the injectors will be upgraded as well as engine management, but perhaps limped on factory ecu with safc til those get upgraded. target HP goal is 300-350 anywhere in there eventually after final tuning.

Anyone have some feedback on those rotors? S5 NA rotors are slightly lighter and higher compression, yet the S4 NA rotors have a more compression over the S5 TII rotors but weight a little bit more. Though I am not sure how the improved lower weight of the S5 rotors benefits over the S4 units. S4 NA rotors seem like the medium safer route to go.

 

If you just throw these in even with a safc chances are that the engine will blow. Id recommend getting a standalone and fuel mods then able to get a tune before you put them in.

 

you will need an Rtek 2.1 minimum so that you have timing control.

 

i have s4 na rotors in my 13b-re. its all in the tuning how well they work. last time i was on the dyno made 525hp. got about 10k miles on the engine so far and all seems well.

 

Some advice for timing adjustment on stock ecu here. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/6-port-turbo-timing-questions-925739/ No results, unfortunately. I may embark on something similar, so I'm curious how it goes, if you do it.

 

nice info thanks guys.. I would have to also get the corresponding counterweight to match the rotors and all is good right?

 

ok think there will be any substantial difference in power/torque between the 9.0:1, 9.4:1, 9.7:1 at say the same boost levels?

 

why bother ? , Try to find another set of S5 , s6 rotors, and call it a day.

Most of these motors are running on a fine string most of the time, due to one or another reason.

the little gain you will get from going 9.7 , will be in vaccum and little torque improvement off boost. With the downside of pulling timming in boost. and wondering if that batch of 91 octane was good enough.

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i plan on going this route when my TII engine pops.. S5 n/a rotors, 60-1 hybrid should be good for an easy 300whp with torquey power band and better mpg. Its all in the tuning.. go conservative with the timing and fuel and it can be reliable as any other setup.

my brother turbo'd his 6port n/a with an H-trim/stage II T3 turbo, stock n/a ecu, 720cc secondaries, retarded cas by 5 degrees, and TII afm. he ran that for a year so far with no problems

 

I was actually searching this same thing.. I'm getting ready to pull my engine apart and I'm sure one rotor is trashed. I've got four s5 n/a rotors that are usuable so I'm thinking about tossing in a whole s5 n/a rotating assembly..

 

9.4:1 is about as high as i would go, yes RX8's have gone turbo but they also blow left and right if the conditions aren't perfect. they have different issues with the side seals going out versus the apex seals on the peripheral exhaust of the earlier 13B's however.

 

thanks guys. yeah now i am really considering away from the 9.7. Maybe go with the 9.4:1, but i know this will throw my rebuild cost up just to get those parts. But I also suppose sticking with the 9.0 is already a step up from the S4 TII 8.5 anyways..

 

So, how far are you along in your rebuild? I know that your engine blew about the same time I dropped my "new' one in........
that just blew a few months ago... lol.

 

i just have everything in pieces still. Finding a job has been more priority over getting my car back together so really not much progress since i last posted about it. Going to be a full year since I blew it and just havent had the large amount of money to get everything I need again. I also took apart my steering rack to depower it, but i want to get the spline welded on it.

 

I'm going to be running 9.7 rotors on my rebuild (fairly stock setup). Using Rtek 2.1 and arghx's 9.4 cr base timing map. It will have a mazdatrix street port, 720cc secondaries an FD fuel pump and rewire, I also hope to have an alch/water injection setup by the time I'm done rebuilding.

I'll post results.

 

instead of throwing away the money on a rtek and water injection system save it for a good standalone ecu. do it once right!! not twice

 

will need the water injection if he plans on boosting the engine much at all up front.

 

The car will be my daily when it's not winter here. I don't plan to run too much power. Just a bit more than stock. I want to use Rtek because it's basically a stock part and I want to keep the car fairly close to stock.

When I get a new turbo it will be something similar to the concept behind this
https://www.rx7club.com/single-turbo-rx-7s-23/autox-fd-dyno-956766/

I'll be getting a water/alch kit regardless.