ISMA GTO RX7 style engine build???
 

So I have been looking for a project to do with one of my space FC's . I posted last week about stitch welding my chassis earlier this week. I've also already built a 20B FC, so that was fun. But I was doing some research and being inclined to do odd and sometimes crazy things. I decided to start looking for information on the 4-rotor 13-J MM engine, and if possible modifying a chassis to suit the engine. So I'd like to ask you guys. Older guys or people in the know and with "access" specifically to help me locate all the information possible to make a build like this possible.

The GTOs were two rotor engines, no?

13J is easy - get a checkbook and buy one. Supposedly there's a few kicking around out there... $50k and it's yours.

GTO's were 4-rotors.

There was absolutely nothing FC about an IMSA GTO car. They were tube framed and completely composite bodies. Relatively easy to duplicate if you have money or a lot of equipment and time.
If your looking for a 4-rotor into an FC tub, others have done that, so it should not be too hard to figure out.

They actually had one of the IMSA GTO's at SEMA this year, was pretty cool. There were a couple of those chassis floating around but last I heard they were all in the hands of caring owners being restored for vintage racing etc.


If your looking to just recreate the engine, thats going to be rough. IIRC they had several versions, some with two sparkplugs, some with 3. They were P-ported with I believe a mechanical fuel injection setup ( I could be wrong about that) dry sumped, etc. True race engines and very very expensive with limited lifespans.

i think they built 2 GTO FC's (maybe 3), one is in mazda usa's possession and it does every trackday/event you can imagine. the other one burned to the ground in 91-92.

the only stock parts on the cars are the taillights and roof. everything else is custom its a full tube frame, double wishbone etc etc

the engine should be a 2 plug version without the variable intake runners (13J-M?), but its been so long since they've opened the hood, i could be wrong.

the 4 rotors seem to actually last nearly forever, the 787B went from 1991 to 2011 without a rebuild, however 13J-M parts aren't in the catalog that normal people have....

do to some events, the 4 rotor FC will be there

Jeff Bruce can hook you up with a four rotor kit. (http://precisionengltd.co.nz/) All said, you are looking at $20-$25K by the time you get a good quad rotor together. You either go P-port and spend a ton on lightweight components or you go turbo and spend a ton on turbo and manifolds. Either way, you spend a ton of money.
Tube-frame chassis-wise, I've plotted a number of approaches for an FD, but they could work for an FC.

Option 1: My buddy runs an FB tube frame that is basically a smallish stock car chassis with a 12A P-port. In GT3 he is the local track record holder. So, find a stock car roller and do some sectioning on either the frame or the body until it fits.

Option 2: I looked at was the sevens only chassis + weld in new suspension mounts. This is basically an FD body + an FB race suspension. You;d have to cut the suspension mounts off and weld in mounts for whatever you want to use.

Option 3: Scratch build it. (the option I like the most) Get the body sourced (pull a mold of an existing shell or buy it from MazdaSpeed), lay out the suspension you plan to use (stock 3rd gen front and rear subframes) and then start connecting it together with tubing. Steal the basic design from a Nascar COT. Remember, triangles are your friend (only shape that requires one side to fail before it deforms)

-Trent

got $100k lying around? if not you're wasting everyone's time.

we race with that series sometimes. they used to do Pro7, but i think they ran out of good body shells, so they built these things. then they have gone 13B since 12A parts are gone too.

that being said they are pretty quick

tube frames are not hard to acquire, many companies build them. The bodywork for the GTO however, is not going to be easy, although I think molds might exist in this country somewhere.

I looked into GT-1 FD bodywork a couple years ago, and its around but not cheap. 4-rotor is not legal i any racing organization currently that I am aware of.

If your looking to do something like this as a street car, I have no idea how your going to get there.

I should probably clear up some things. First of all, while I would love to be able to track the car in all likelihood this would just be a rarely used "hot street/ show / Very rarely driven on the track " variant and not a dedicated race car. Secondly, there must be some way to modify and widen and lengthen a stock chassis FC to accept the engine. While having the body would be absolutely fantastic it's not something I would consider a must have. Finally, Thanks to everyone so far for your support opinions ect ect. Finally, I'm drawn to this engine because I've built race specific 20B's and 13B's for years. The idea of a true 13B based 4 rotor is something that's appealed to me for a very long time. However I haven't been able to find much information on it and as such I'm working off grainy photos and speculation as to what would need to be done. E-shaft aside it's basically off the shelf parts when your talking about the 400HP dual plug version, and Logan at Defined will modify stock housings to support late trailing plugs if I ask.

I've got the business,spare time and a spare chassis.
I'm kinda disappointed you would be so negative. Especially given the number of homemade 4-rotors being built lately. Don't get me wrong I get what your saying There is ALOT to do, but it's not impossible. Even if it ends up just being a 400HP NA 20B with a similar body, that's still an accomplishment in and of itself.

Sarah from bmi contacted me earlier this year offering to sell the 4rotor, contact them I think they are still selling it.. If not you can buy a new 4 rotor crank from pulse performance for 10k an start from there. Don't forget the dry sump and cooling setup!!

are you talking about this car?

1990 Mazda RX-7 GTO - Images, Specifications and Information

People are being negative because what apparently you're looking for is completely different from what the OP made "build like this" seem - there's a big difference between something that looks sort of right and actual race iron. And posting in the "Race Car Tech" section tends to imply things.

People have crammed 4 rotors into FCs, but that's not a 13J - the actual race engines effectively used two irons similar to the 20B irons, albeit one mirrored from normal for the 20B. People have put widebodies on FCs, but that's not a GTO car, which was a tube chassis with a drivetrain and suspension specifically designed for the job, and wind tunnel development.

It seemed pretty clear to me from his title and first post that he wanted to build an homage to the great GTO car with an actual 4 rotor engine in a production FC shell.

He probably posted in the race car section because people here would be familiar with the original car and have ideas on how he could get/make some parts/info to achieve his goal.

Lets start with a little help to questions he asked.

I decided to start looking for information on the 4-rotor 13-J MM engine, and if possible modifying a chassis to suit the engine

As others said, you should forget the bespoke 13J 4 rotor and go with the relatively affordable 4 rotor short crank kits now being made. External features like a similar airbox, alternator location and top aluminum plate will give it the right look.

Once you cage the shell with forward bars to the strut towers and a horizontal bar off the a pillars across the dash you will be able to take out the firewall to move the engine back.

You could go further and do a "front half" build using just the firewall back of the FC shell so you could get the good details of the engine bay and take the opportunity to swap out the front suspension for something a little more race car. It would be pretty cheap and easy to buy a wrecked out tube frame car and graft the front end onto your rear unibody/cage. You would get the suspension, brakes, centerlock hubs, steering rack, speedway swaybar, etc and not have to sweat all the engineering on the geometry.

You can start with a 2nd gen IMSA GTU fiberglass front hood/bumper/fender section for the low low bumper and modify from there to get the GTO look. Someone does have the molds for these still.

I will try to find a bad ass Australian 3 rotor FC race car build I remember seeing years ago so you can get some ideas.

The article is gone but this thread has the pictures.

https://www.rx7club.com/2nd-generati...ss-car-256561/

you can still get the gtu (gts-2 ) imsa parts from mazda motorsports. They are similar in width to the gto but do not have the wide doors, instead it widens gradually from the middle of the door into the rear quarter. The best one to get is the clayton cunningham racing ccr version with the lower nose.

I looked into the same build and phoned 100's of people , finally tracking down the original builders of the body. They said the molds were thrown out years ago. There is one car in japan and one in the us. A guy in south america ( Costa Rica i think)somehow has the gto body ( in yellow and pink! ) on a half ass tube frame. His car is on youtube somewhere. Maybe make him an offer and ship it to the USA.

Ummmmm.......
 

So sorry to revive an old thread. However, I believe this to be what you're all looking for.Mariah Motorsports by Design Energy Inc. RX-7, Rotary, KitCar and Sportscar Specialist Go to products, 2nd gen, exterior body styling. They have the gto complete kit for fb and fc. And yes it will work with a stock frame.