JB GT3 996

2004 996 GT3 3.6L ENGINE - INTO A - 1998 996 C2 3.4L BODY SHELL[/B]

Was really hoping I could rack brains re this - seems not many have done it before!

We have been looking at the body shells & PET diagrams.
- Understand the GT3 engine/box is longer & heavier (?)

The 2 key parts that seem different are on: PET "REAR END" DIAGRAM - 801-35

A - TERMINAL PIECE - item 1 - this is VERY different.
C2: - 996 551 973 00
GT3: - 996 551 173 90

B - REAR WALL - item 9 - large piece - but seems quite similar?
C2: - 996 502 911 00
GT3: - 996 502 191 91


Would most appreciate any advice re:
- Are these the relevant different body parts?
- any other different parts people can think of?
- Can we use the existing C2 REAR WALL to mount engine on to etc? - as guessing its a big job to swap in a GT3 REAR WALL!!

many thanks
JB

10 GT3

Don't for sure how much different the chassis are, but the Mezger engine is quite a bit bigger than the M96. The crank case alone is over 4" longer. I also suspect there are some significant wiring changes that will need to happen. The Mezger only runs e-throttle, which did not go into Carreras until 2000. You also need the transaxle for the GT3 engine as the G96 transaxle from the Carrera will not matte to the Mezger block.

JB GT3 996

many thanks 10 GT3 !!

I should have clarified:
- we are also swapping in my GT3 Cup Transaxle/Gearbox
- also fitting my GT3 engine wiring harness to manage GT3 engine.

The GT3 engine wiring harness looks like it will "plug & play" into the existing C2 harness - @ just behind the seats - hopefully!

1 - do you think this will still cause issues with the GT3 e-throttle?

2 - the GT3 box is longer I think - true? fitting issues?

thanks again!

JB GT3 996

nb - advice received from UK panelbeater re fitting in GT3 larger engine:

we are struggling to fully understand it!

the difference is the rear hanger that is shaped like an arch at the rear of the car and the engine mounts.
These can be modified, or by using parts off your old shell
This modification has been done over here many times when required more by the guys who race these cars.

So if you look from the back of the car with engine and gearbox out, you will see a cross member, this is different either by thickness or the cut outs.
There is also difference in engine mounts brackets which have to be altered, this is easier if you have your old shell.

JB GT3 996

ps

996FLT6

Since the gt3 shell is based off the 996 c4 would it be an issue? Mike

JB GT3 996

thanks Mike

Yes, aware of this - but C4 shells very hard to find!
To deal with this, we plan to:
- front strut brace
- bolt in roll-cage - ex factory issued GT3 CS 2004
- seam welding: - small spot welds along major points. The bulk of the work is on the side sills

any thoughts on how we are going to accommodate the GT3 engine/box?
cheers

pete95zhn

Long story short:

Engine/trans attachment points at front: Move threaded pins to those other positions about 5 cm away.

Engine/trans attachment points at rear: Modify the engine hanger plate to fit C2's chassis points. I modified the chassis, but noticed later that cutting & walding that aluminium plate would have been much easier.

Otherwise bolt-on. BUT cooling plubing is different, you need new pipes and hoses to engine bay. (At center tunnel they're similar) And a third cooler to front, there's a complete set available.

Clutch slave cylinder works, no need to change.

You have to modify the wiring loom from Motronic to engine bay only a little: Major issues are Variocam's wiring ( you may have to add few wires ) and ignition sequence, they match at Motronic's end but switch at that large round plug in engine bay.

Your GT3 engine has traditional gas-by-cable, so if your chassis is similar then there's no problem.

Some wiring confirmation with the ABS, shouldn't be anything major if your chassis is 2WD and you're using a Motronic out of a GT3. Cup's one might have issues....then it could even be easier to disable or buy a Motorsport unit.

Fuel pump and filter. And your tank is only 64 liters, no way to install that 89l one, unless using a fuel cell at frunk.

Crossmember at rear suspension is the same. Drive shafts are of the same length, I'm not aware if GT3's are thicker but turbo's are.

Been there, done that. But with turbo's engine and trans...

996FLT6

^The street 6 gt3 engine is e-throttle not cable actuated like what cupcars have and op's 98 c2. JB I guess u have the pedal assembly for the egas or u plan to convert to throttle cable. If throttle cable I'm curious how easy to do that. Mike

996FLT6

JP if you fortifying the front with front strut bar u mite as well extend rollcage to front struts for even more strength. Mike

pete95zhn

mkI has cable throttle, mkII E-gas.

Is it going to be street or race car?

Some more issues popped to my mind when thinking while sleeping...
-oil quantity measurement is different on M96.0x and M96.7x engines, so if using Carrera's instrument panel you will not be able to use electronic oil quantity measurement. Get an oil filling tube with a dipstick and ignore warning in intrument panel. If you choose to use GT3's instrument panel (from a mkI!!) oil quantity measurement will work -with almost everything else-, but fuel quantity will be off...
-mkI's Motronic is easy to integrate to '98's chassis, but mkII's not. Reason for this is CANBus...real PITA...actually impossible without changing a lot of chassis' wiring. IMO for a street car use mkI's cable TB and Motronic
-IIRC GT3 has WBO2's, '98 Carrera (Euro) has only NBO2's so there's few more wires to be added

If this is going to be a racer you can skip all the electronics problems just by using a standalone ECU with associated display unit and race car ABS (if needed).

JB GT3 996

Pete - you just made my day - thanks a million!
Am meeting with workshop & panelbeater on Monday - so we are at D-day etc.

Key issue noted from your advice:
We have an early Mk I C2 996 with cable throttle - so issue with the e-throttle of GT3 engine
- can we adapt? - or forced to start from new....using just what?

NB: I have a very sweet, upgraded, COMPLETE GT3 CS 2004 - just with a destroyed body ex track bingle!
- hence using the C2 shell to resurrect is the plan.
cheers

JB GT3 996

thanks Mike
YES still have pedals- have my entire GT3 car still, just with a wrecked up body on it!
Really have no idea how to go forward with the e-throttle vs cable dilemma.
- no one here in OZ thought of that!

Any advice.....? - seems we should somehow keep it e-throttle by using all my GT3 parts on the 1998 C2 shell?
cheers

JB GT3 996

Thanks again Pete

Definitely a road registered car - with moderate club level track use - just what a GT3 excels at doing!
I've owned my 2004 GT3 for 5 years & did just that with it...until the big track bingle = wrecked GT3 body.

1 - can we swap in my 2004 GT3 instrument panel/pod in the '98 C2?

2 - NB - GT3's in OZ dont have the huge fuel tank (60l only) but it still is a different shape to the C2 tank I understand - so guessing we will have to use the C2 tank so as to fit in the chassis.

3 - can you pls explain this a little more? " for a street car use mkI's cable TB and Motronic"
ie leave the e-throttle gear in my GT3 (dont swap over?) - run the existing C2 Mk I cable throttle, but add on a separate Motronic?

cheers

NineMeister

To convert a 996C4 shell into a GT3 shell to fit the engine requires the rear bulkhead to have a bulge panel fitted (to clear the oil tank) and the engine mountings replaced in the corners of the rear back panel. I also think it requires the gearbox crash lug on the top of the rear cross member.

These photos of a 9m96GT3RS-R shell we are currently preparing show these details.

I hope this helps to clarify the installation?