just kinda wondering what everyone thinks about swaping a renisis motor into an fc. Would the weight distribution be the same? would it bolt up to the stock rear-end? Wheel base? has anyone ever thought about this or done it?

 

It's been done before. I forget the guys name

 

It can be done but prepare for making a new crossmember to fit the new engine and a whole new wiring harness. There will be alot of custom parts made. But if you really want it you can do it.

 

not worth it.

 

+1

 

ton of work, but it would make for a really nice NA.

unlike a 13BT, the rx8 engine needs mounts, and some kind of standalone ecu

they are also still expensive, for 3k you could have a rebuilt 13BT in there running

 

I agree, a nice S5 13B-T rebuilt with a street port would still come out cheaper than the price for all the things to make the 13B-MSP work.

 

ya i was trying to stay away from a turbo (dont get me wrong i LOVE the turbo motor too i have had 2 turbo cars so far.... but i really am trying to stick with na) . i work in a shop so custom making parts is no problem. i was thinking it could be done for under 10k especialy if i do all the work

 

It's far and away a better engine than the n/a 13B so I have no idea why people say it isn't "worth it". That's a matter of opinion. I'd do it in a cold second if I ever get the chance. I think it's "worth it" but that doesn't mean I want to spend the time and money on it right now. I've got a little project I've got to finish first.

It's not hard to fit the Renesis in a 2nd gen. It's not expensive to make it work. It's actually quite easy if you know what you are doing. Since I'd never ever use a J-spec TII engine without a rebuilt which means money, and I have yet to find a TII out there that is worth owning as most owners treat them like crap (present company not necessary excluded), it's really not cheap or easy to do a TII swap properly. That is the key though. 99% of the people out there are cheap lazy asses who believe "properly" and "cheap" go hand in hand. They don't! Pick one. The "budget rebuild" is also not one that goes hand in hand with the word "properly". To do a TII swap properly (at least one that I'd drive around), will set you back a couple of grand minimum. It takes nearly a grand just to rebuild an engine cheaply. For each engine you still need some ecu and exhaust attention anyways. The total cost would be pretty close between each. If you don't want 300+ hp, which you won't get anywhere close to with a stock TII engine anyways, a Renesis is fine. You don't have the longevity disadvantages of a turbo over an n/a yet you'll still have decent power. The Renesis can get you over 200 rwhp pretty easily which is actually quite nice. I've seen higher than that. In a car as light as a 2nd gen, it "can" be a mid 13 second car. That's plenty fast. Especially for someone used to driving an n/a around.

 

I did a T2 swap on my car, did the whole thing... Trans, diff, brakes, rebuilt the engine, stand alone and so on... After i did it... I'm happy...
It is a matter of opinion like rotarygod said, and one thing you have to remember is what do you expect/want from your 7. What is your goal? What kind of performance you are looking for, and will it be worth it by doing that swap over a t2 swap? and most important what is your budget?
You have to do what you want, but keep in mind your goal... If is for power i would say go turbo RE or REW, if is just for longetivity Renesis would be good for you...
In the end is your money spend it wisely...

 

look up 'sen2two' something like that

 

My palm is stuck to my face . . .

 

DUDE....DUDE.....just do it....dude...just do it...dude....and tell everyone i convinced you to do it...because dude...your gona do it...

 

Isn't alot of the renesis power due to the way it's intake was made? At least thats what I recall hearing and that it wouldn't be that much faster than a s5 motor without the renesis intake.

 

"The engine entailed two major changes. First, the exhausts ports are no longer peripheral but are located on the side of the housing, which allowed engineers to eliminate overlap and redesign the intake port area. This produced noticeably more power, thanks to a better compression ratio. Second, the rotors are shaped differently, especially their side seals and low-height apex seals, which offer optimized lubrication."

Thats off some info i found about the 13B-MSP.

 

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/6-port-msp-idea-829012/

Rotarygod, I am just as impressed with the Renesis as you are, but I have never seen a viable, cost effective way to control the auxiliary port sleeves.

 

Seems to me that the only way this swap would be worthwhile is if all the EFI stuff on the Renesis like the multi-stage intake, 3 sets of injectors, etc. can be controlled. I don't think there is an inexpensive standalone that can do this, and it doesn't look very viable to transplant the Renesis EFI system into a 2nd gen. With all that stuff wired open, low end and midrange must be awful. Just my opinion though.

 

Keep in mind that in no way am I saying don't do a TII swap. I'm just saying that the Renesis is a good engine that is very worthy of using in a swap.

If you want to control the aux sleeve motor, you really only need an rpm switch and a power source. That's easy. You can do the same thing with the VDI valve. The hardest thing about the Renesis will be making the motor mounts which really isn't that hard. You can retrofit a cable throttlebody to the manifold and then use a stock ecu with a little work. When I say "stock" I am referring to an Rtek. Sure it will still have an afm but the S5 version will do away with that soon. The other option would be to use the stock harness with the Power FC adapter cable and a Power FC. I know ecu solutions cost money but you should be doing this with either engine swap anyways so we'll call that even. As far as fuel just run 4 fuel injectors rather than 6. The newer Renesis engines went back to 4 anyways. Adapt the S4 omp and use a bicycle brake cable to actuate it from the tb. The key is in getting creative but it need not be difficult.

 

^owns

 

the not worth it part is just from a cost standpoint, and it should get better. here's an example

if you look on ebay, there are plenty of t2 engine/trans for like $1100, hopefully you get a decent one, and are able to rebuild it without buying housings, and you can have it running in the car for about $3000-3500. stock engine stock turbo, 220hp?

the renesis is $3000, then you need an ecu, etc etc

in every other way its better though. i'd much rather have the rx8 engine vs the stock turbo setup

 

I still don't see how there's an appreciable difference in cost between them. One thing that we see repeated here over and over again is that many projects are done cheaply yet usually end up taking more time and costing more in the end.

 

I never even thought of the RPM switch. I had always assumed that Mazda controlled them via both load and RPM, not just RPM only. Even both map points shouldn't be a big deal with a few extra aux outputs on most standalones, and 4 injectors makes things a lot easier.

Edit...The one thing that keeps going through my mind however is that if I have to buy a standalone and do the fab, then it makes a lot of sense to bolt in a fresh TII engine and make the same power, more torque and have something I can by standard parts (ie. downpipes) for.

 

If you're going to go through all that trouble, why not go for an n/a 20b? Cost would be fairly similar if you're doing it yourself anyway.

 

You can find the renisis engine with the harness and ecu. Ive seen some on ebay.

 

From what I have seen in the 04 Rx-8 FSM, the aux ports are duty controlled and have a feedback system with a position sensor. Just Applying voltage with an RPM switch would probably fry the motor.





You would at the very least need a standalone that can send out a duty signal and has hysteresis control so the ports aren't snapping open and shut abruptly--at least, if you want it to drive like a stock Renesis. At the minimum, you would have to figure out how to open and close it reliably (without burning it up), although it wouldn't be as smooth and precise as the Rx-8 PCM.

I suspect the secondary shutter solenoid valve is duty controlled as well. I say this because, on previous mechanically controlled throttlebodies, the two secondary butterflies (on the smaller bores) always opened progressively, after the primary opened. The point at which they opened was adjustable by a few bolts. On the Rx-8, there is a single butterfly for the TB, and the SSV is then opened. I doubt it is snapped open at a fixed rpm under all engine loads/throttle position etc. I mean you could just snap it open, but it wouldn't drive the same.

All these little issues show just how sophisticated the Rx-8 really is...