OpelGTguy

I have owned my GT for 17 years, spent 14 rebuilding it from bottom up and 3 years beating the daylights out of it. It handles well, but suffers from a motor that has no cojones (It is a 2.0 liter, headers, 38Dgas Weber, K+N filtered) Any and all Opel solutions result in about125 or so horsepower. This year I am ripping it all out and installing an RX-8 motor that will triple the horsepower, lower the center of gravity and will take weight off the nose. It should also be scary quick in SCCA HSM races at less than 1900 pounds....
Actually installing the motor shouldn't be a problem (I have some great help from a friend that builds drag cars) But the rear end is an issue. Opel rear ends, U joints and torque tubes grenanade over about 150 horsepower. they also all came with open rear ends and drum brakes. Since I have to canibalize an RX 8 and the rear end matches the driveshaft/trans anyways it would be great to find a way to make the RX8 rear end work in a significantly narrower car. Anouther problem is the torque tube. If anyone can tell me what it does I would appreciate it. I have read Wikipedia's explanation and I still don't get it.... I assume I will need to add a panhard bar to the rear end?
If anyone can help with this, me and my Opel would appreciate it!

8 Maniac

iTrader: (1)

Out of curiosity, is there a specific reason you picked the 13B-MSP (RX-8's engine) over other 13B rotary engines?

Are you planning on using forced induction? Realistically, you'll only see about 200 hp from the renesis without FI. Those are definitely good numbers for a car under 2000 pounds, but not quite triple the numbers you mentioned.

Sounds like a fun project... I look forward to seeing the results!

OpelGTguy

i am clearly not well informed on rotary motors so i am here to get an education of sorts. I was of the impression that they were 250 horse/not a whole lotta torque motors. From there I have the advantage fo having a pre emissions car that a rotary's high RPM would just love, and the light weight needs very little torque. The lighter, lower weight is also a huge turn-on as I have been autocross racing it this year and the cars poor weight distribution has been a hinderance.
The car uses 1 inch front, 7/8 inch rear, front 1982 BMW325 brakes and poly bushings all around. Lowered lenk Racing suspension, Ball Joints, tie rods, rack ect... are all new and still it tends to understeer a bit. In typical German fashion, everything is overbuilt. It has a 75 bhp motor stock, but the bottom end of the motor looks like it came out of a diesel.My starter motor is 32 pounds lol.

OpelGTguy

Are the transmissons the same? and where can i get specs on the dimensions of the engine? There is an Opel in Texas with one of these conversions and I have seen pictures of a new style NA motor.(I call it Renesis, but I may be incorrect) If there is anything you can help me with, let me know.

YaXMaN

Yah, sounds like an interesting project. Seems as though the rotary swap is fairly popular with the Opel GT. Have you looked at all the forum info available for RX7 13b swaps for the Open GT? There's a bunch.

You also might be able to find some useful information just looking up Renesis swaps into other vehicles if you can't find info for your car specifically. Here's a quick example... the swap didn't require nearly as fabrication as your swap might because much of NC and RX8 chassis is shared, but there's some great photos.
https://www.rx8club.com/australia-new-zealand-forum-37/renesis-nc-track-car-build-158121/

Page two talks specifically about the driveline. He didn't have to shorten the half shafts, but I see that it's common for the Opel GT guys to do fender flares and widen the body work to accommodate a different rearend.

Anyways, good luck.

cavemancan

Be mindfull which Rx8 your getting the motor from. Is it a manual transmission? 6 speed manual or 5 speed manual?

The 6 speed manual tranny cars make about 232 HP (6 intake ports) to the crank and about 170 to 180 wheel horse power. I am not sure about the other versions but be prepaired for significantly less power (I think like 40 HP less).

Note with tuning and supportive mods (intake, exhaust, CAT'less midpipe, BHR Ignition sysem) the 6 port engine could make around 200 to 210 wheel horse power (maybe like 260 crank horse power...guess).

8 Maniac

iTrader: (1)

The renesis is rated at 232 hp @ the flywheel, so that's before drivetrain loss. A strong RX-8 will typically dyno in the 190-200 hp range. Of course, your build might get a little more power to the wheels, but I wouldn't expect a whole lot more.

If you're looking for significantly more power than that, you'll want to consider FI. At that point, it might be worth looking into some of the other rotary options as well.

OpelGTguy

That is an option, but the wider the back gets, the more the carwill understeer.

OpelGTguy

My plan was to buy a whole, dead car, that way I could use the trans (gonna have to move the seats all the way back) Do you realize how much it sucks to drive a 4 speed in 2012?

OpelGTguy

I'm an open book on this stuff. What would make the most power, and how much room do I need? I suppose i need to find a GT without drivetrain and measure everything. Or get my hands on a dead motor of the type I intend to use and mock it up.

alnielsen

iTrader: (4)

I once saw an Opel GT with a rotary engine installed. The owner was from Michigan. I don't know his name. It was 20 yrs ago.
I wouldn't use a Renesis for your project. I would get a 13B from a earlier RX7 FC. The electronics will be a lot easier to work with. With a street port, you can get over 200 crank horsepower.

8 Maniac

iTrader: (1)

How much power do you want and are you willing to mess with turbocharging?