johnnydiii

I am considering a Boxster project where I would swap a cup motor into a Boxster and was wondering if the trans can handle it. I was under the impression that Porsche, as always, tends to overdesign their parts and that it might be able to handle it as long as you avoid "hole shots" and side stepping the clutch. This would be a track only car with all the unnecessary parts removed and lighter body panels installed wherever possible.

What model year chassis should I start with as a core?

arenared

The M96- and GT1-based blocks and transmissions are totally different. There was one guy in Australia, I believe, that fitted a GT3 X51 block to a 986 while using some kind of transmission adapter plate, but there was a lot of other "custom" required. There was an Excellence article on it, I believe. The S tranny is essentially the same as the 911 tranny (running in reverse) but not the TT/GT2/3 trannies.

johnnydiii

What would be the biggest motor you could fit on the Boxster S trans without going the adapter plate route? I would like to avoid getting in to the guts of the motor to jack the performance up.

amondc

I think you can put a 3.4 996 motor in pretty easily. not sure though

johnnydiii

Hi. Thx for the reply. You know which Excellence that appeared in? I checked the Excellence archive back a couple of years and wasn't able to locate it.

arenared

I will have to see if I can dig out the Excellence article later. It was pretty recent--2 months ago?

The biggest M96 motor that still uses a Boxster-compatible ECU interface is a 3.8L X51. I believe the controller, Motronic version ME7.8, is in '03+ models. An earlier Boxster '00+ will work, but you will spend some money changing out other components to be compatible with different buses/protocols. If it's a track-only car, then you may not care about cruise control, etc. Also, a track-only car, you might only care about WOT, and CELs or part throttle performance are some corners that could be cut. A very early Boxter '97+ might work but you're probably going to spend some grief with wiring harness issues, etc., and you'll want the 3rd radiator and brakes from an S eventually. The S started in 2000. Generally a '97+ is only good for an early 996 non-eGas 3.4L. The biggest impact of the 3.6L and bigger is the control of the VarioCam+ which the older ECU cannot do.

There is a guy 'tholyoak' or something similar on some of the boards (mainly check RennTech). He would be a good person to track down.

glencase

Don't count on it, I bought a 99 with 79k mi on it and it ran and drove great for about 8k miles then something in the diff let go and it needed a trans, during that whole process I learned (don't know if it is true) that the trans is Audi design or something and the S model just has an extra gear and it is not any beefier. Take it with a grain of salt a tech told me this and he could have been feeding me sh#t since I was lapping it up.

You did say that you wanted this to be a track car right? Transmissions take some serious punishment on the track, and with the extra power of a 3.4 or whatever else you decide to stuff in it, will only add to the stress.

Good luck on your project, that has been a dream of mine to build a kick *** boxster that could kill just about anything on the road and be stealthy about it.

Turboflyer

I too was already to upgrade this and swap that for more power. I drove the new caymen S with 295 HP. I was told it was more like 305. In any event not worth the change and expense from 250. I also drove a vehicle with over 400 HP. Now we are talking difference. I was all set to do as you. Go drive something with 400 or even 300. I dont think you will want to spend the time and money on mods. If it is small mods for sound or looks yes I can see that, but do yourself a favor and check out what that change really means seat of the pants first. Just so you know there will always be something faster than what you have no matter what you have. Where do you think the surprised look originated.

AlpharettaRK

My '99 has about 40,000 miles with a 3.4 and the original trans, some of it on the track - no issues. In fact I recently got tired of the "sport" clutch and put a stock clutch back in withno issues either. It's got enough clamping force to break loose my 285 Plot Sports, I don't guess I need any more than that!
Cheers
Randy

blinkwatt

What don't you like about the 'sport' clutch?

Where did you get it from?

AlpharettaRK

It was a Sachs sport clutch and the pedal effort was way too high to drive in traffic. It wouldn't be an issue for a track car.

arenared

May 2008.

easyC

The australian Boxster used a GT3 engine (early 996 version I think), but it had TONS of custom work done to it... They used the 986S 6-speed but had to build a custom housing so that it could mate to the engine... there was tons of other custom work too.. .like having to run the intake in the opposite direction (towards the drivers compartment) the cup engine would have just as much plus more custom work needed... The biggest engine you can put in depends on the year of the engine, the year of the donor car, and the depth of your pocket book... generally speaking (without MAJOR electric hurdles)... 3.4 from 996 in early 986, 3.6 x-51 from 996 is the biggest for a 986 01-04, and 3.8 x-51 into the 987 based cars... Todd (tholyoak) is a great guy to ask questions to... look him up at renntech...

pecivil

I am 10k miles into my 3.4 swap (on a 2000 Box) running the stock tranny with no issues. I added a AASE Lt Wt fly and new stock clutch with the swap.

Knock on wood

the 3.4 really makes the Box Fly.