Here's a good question. How much fabrication would have to be done to:

Install a Renisis rotary (250 Hp) along with it's 6 speed transmission...

I know you would have to get the computer and everything along with that, but you think the motor mounts are the same?

Humm.. interesting (expensive) project

-Markus

 

i dont think theres anyone out there who could answer with experience!

i doubt the motor mounts are the same, and i also doubt there would be TOO much fabbing involved.. id be more concerned with the tranny's u-joint to mount to the driveshaft.. im not too familiar with mazda's drivetrain compliacy, especially between the 2nd gen rx7s and the rx8, so..

the worst part would be wiring it all up i would imagine

but im no expert..

 

i dont know but most likely itll work but alot of money is gonna go in it. isnt the engine more larger than the fc engine?

 

i dont know but most likely itll work but alot of money is gonna go in it. isnt the engine more larger than the fc engine?

 

A lot of work. Then again, it is a direct swap w/ zero relocation required.

Basically, what I'm telling you is that it is completely 100% speculation at this point. No one, other than Mazda and a few select shops have gotten their hands on a Renesis engine.

The amount of fabrication work would be up to how picky you are about fab work. You could mickey mouse it or you can spend weeks just to figure out the exact mounting locations.

Sorry to sound like an ***, but that is a truthful answer. This topic shows up in the 2nd gen area and the 3rd gen area quite a bit now.

 

there are already wrecked rx-8's in japan. one hit in the *** really hard was going for $5000

 

I consider this one of my options.
The Renesis is shorter and lighter then the 13B (304LB).
I expect the same or less work compared to fitting a V8.
It will definately require the complete harness & ECU.
Also the intake air filter & plumbing are part of the performance tuning.

 

I wonder if there is some kind of hybrid you could put together in terms of fitting an FC tranny to a Renesis motor. I don't think fitting the actual engine would be an enormous affair but re-wiring the car would not be fun

 

What about fitting just the RX-8 6speed tranny into an FC?

 

A custom rear mount & driveshaft would do it.
We will have to wait & see if they changed the bell housing bolt pattern.

 

not sure if the renesis would sit in the same place as the fc engine. i remember reading that the renesis engine sits farther back behind the axle or something to that effect. Also how much would a new or used renesis engine cost?

 

but since the engine is lighter wouldnt that mess up ur weight balance on the fc?
oh and could u swap the rx-8 rotor to a rx-7?
Im asking this because since the rx8 rotor is way..lighter just for the hp but if u switch the rotors would it even out the torque and hp?

 

The Renesis is physically the same size as the 13B just a little lighter in weight. The motor mounts are completely different. On the 2nd gen they are on the intermediate housing, through the oil pan and extend down and away from the engine. On the Renesis they are on the front rotor housing and extend straight out from the engine. You would need to rework this problem.

Since the tranny was designed to fit the RX-8 and not the RX-7 who really knows if it will fit or not. I would have to say probably but with a little work. You will probably need to fab up a driveshaft as well unless you get lucky.

Since the entire engine is controlled by computer you will need the RX-8 ecu. I don't see a Haltech completely controlling one of those. It is a drive by wire system as well. Change the throttlebody to a cable style or get the actuation system from the RX-8 as well.

Will the rotors interchange? Who knows. Probably since both engines share the same internal dimensions. The Renesis uses different style side seals and adds a 3rd seal on the side called a cut off seal. If you use lighter rotors you also need the corresponding counterweights.

Who cares if it messes up the balance of the car? When you change your exhaust out to a new one, or add a piece of stereo equipment, or change wheels and tires, or have 20#s of books in the back, you mess with the cars balance. You get the idea. It isn't enough to be appreciable.

For all of the time, effort and money involved in such a swap, I can't see a single person who could justify it. If you are going through this much work why not just build nice turbo setup or buy an RX-8? It will be cheaper and easier either way you look at it.

The RX-8 I drove didn't feel all that impressive. My GSL-SE is much stronger up to about 7000 rpm or so. Since I didn't redline the car I can't judge how strong the top end is but it feels like my Civic up through the midrange. I may buy an RX-8 but I sure as hell won't waste all the time and effort in doing an engine swap to one of my RX-7s. To each his own though. It admittedly would look very cool.

 

The 20B was said to be Impossible, or close to It, due to fittiment Issues, and the like, but It was done...

We can only speculate for now, as for compatibility b'n parts until someone starts tinkering.

 

Dude you must be smoking some great crack my freind. It feels like my civic through the midrange?!? How the hell do you figure? I honestly dont beleive you drove an Rx8 if you think your GSL-SE is much stronger up to 7k or your civic. Have you read the reviews on the RENESIS?? Do you know that there are countless features on the RENESIS that make it far better than the 13b?? If you read the May issue of Sport compact car youll see that some prototypes have had a valve sticking problem which dont allow the ports to open up past 6250 rpm. They reported this was similar to losing about 40hp. Now i feel that you must have had a similar problem. If in fact you even drove an Rx8 which i seriously doubt

 

Lighter in weight, NOT!
Lighter than the FD3S twinturbo because of ---no turbos.
Its no lighter than any other NA out there.
Still uses the iron front/mid/rear housing with aluminum rotor housings just like ours.
Mounting is supposedly similar to the FD3S.

The tranny is just the 6-speed similar to other vehicles six speeds(s2000?, Miata?, can't remember where Ford sourced it from). Mazda didn't design it.
They just pulled an available tranny off the shelf and bolted it on with a Renny spec bellhousing and gearing catered to the powerband.
It won't mess up any balance issues on the FC. If anything, the mounting selected could possible improve the balance. It depends on the sanity of the welder and measurements taken.

Weld up some mounts, convert to carb or standalone EFI, add throttle cable to get rid of the drivebywire stuff, easily made custom driveshaft......
The only question is how soon before someone smacks an RX8 into a wall so that someone else can part it out for the drivetrain.

 

I was just kinda skimming over some of the features of the renesis and There was a picture that made it look like the rotors were a different shape. Have they changed the shape of the new rotors? or are they just the same size with a lighter material?

 

Here's a novel concept... just buy an RX-8

 

Hey buddy, do you know what the retail price is on the new rx-8?
Wow I wish I had that kinda money laying around... Since you do youll be the first to buy one and then you can keep your rx-7 collection going.

 

Ryl: There are a few of us on this forum who got the chance to drive an RX-8 at the same time. The one we drove was plain and simple weak. Maybe it was just prototype bugs but it was not impressive by any means. It did feel like a Honda on the low end. Slow. Yes I've read the reviews but I have also driven the damn thing. I like the car and will probably buy one sooner or later. Have you looked at the dyno charts? Have you seen the power to weight ratio? Compare this to my streetport GSL-SE and it is very easy to see how my car feels faster. All of the Renesis power comes on up high which is where I did not rev it to. It has also been written in the reviews that it is very similar in feel to the S2000 in that you have to rev the hell out of it to really get moving. I believe it. We didn't get a chance to get on the car that hard but those of us who drove it all came to the same consensus granted two of the other drivers have very fast turbo RX-7s. Saying all of this it doesn't mean that the Renesis isn't better than the 13B though. It is by a long shot. I'd hate to drive that car with a n/a 13B in it. Power to weight ratio would be like a 2nd gen convertible. The sticking valve issue isn't relevant anyways since I only took it up to about 6000 rpm. If there is a 40hp loss or so above this point then it is very obvious that I wasn't where the engine made most of its power. The car runs a 14.5 quarter mile. My GSL-SE runs in the mid-high 14's as well but shifting at 7000 rpm. Whats not to believe? Go drive one when they hit the showrooms. You'll see. Nice car, great n/a engine, but by Mazda's own admission not designed for neck snapping acceleration just smoothness. Believe me or not I know something first hand that you don't.

 

do you think they kept the same eng/tranny bolt pattern?

oh and ryl: he did drive it , i saw the pics

mike

 

well, supposedly all the RX-8's that are out before it goes on sale suffer from the AUX ports sticking closed (all these motors were hand built) meaning each car is down about 40hp. Magazine tests have suffered and super street didn't even bother w/ acceleration tests until they could get a car that ran right.

 

jon88se: Actually it was SCC that discovered the AUX port problem w/ the RX-8. They told Mazda and Mazda immediately picked up the car to attempt to fix/research the problem. Whether this was an isolated incident OR whether it occurs in all RX-8s is currently not known. So far, the test car that SCC got to play with was the ONLY reported case so far. (So it is not ALL magazine tests that have suffered).

I'm just trying to kill all rumors before they spread.

 

Even though no other magazines mentioned it, it may be because they never bothered to dyno it and just took Mazda's word for granted. But, on the other hand, it seems that they would notice the power not increasing as it approached its claimed max power at 8,500 rpms.

 

SCC discovered the stuck AUX ports because they did dyno the car. Keep in mind that they found this out by reading the dyno. They didn't exactly "discover" a stagnant amount of power, felt by their butt dyno. They ONLY found this out on the dyno.

Also, keep in mind that the RX-8 does not have huge amounts of torque. Nor, is the RX-8 a true sports car (like the RX-7). The RX-8 is set to compete w/ cars like the Infiniti G35, Toyota Solara, Acura TSX, etc. Therefore, a goal of the RX-8 is obviously a smooth comfortable ride (along w/ a relatively smooth engine as compared to...the 13B-REW).

Therefore, it would be safe to say that the "power" cannot be simply "felt" or "noticed" by your "butt dyno".