BMW V12 in Boxster S with Tiptronic Help!

[alipendier]

I have a 1999 Porsche Boxster S with the tiptronic transmission that I am swapping the motor with a V12 from a 1989 BMW 750IL (M70) after a frame stretch. I plan to get the HP really up there (maybe 700 or even more...) but I need to know three things:

1. Is the Porsche tiptronic gear ratios compatible with the BMW V12 motor?
2. What is the max power the Porsche tiptronic transmission can handle? Basically do you think it can handle up to 700HP?
3. Any suggestions that can help with the engine swap...

Thanks

[Lobo1186]

1) not sure what you mean
2) no (try talking to GBox they make boxster trannies)
3) maybe use a different engine.

there are some out there trying to get LS motors in there and well if it successful it will be a much better motor thank the V12 you mention and cheaper to get power from.


but with time and money you could probably do it.

[landrovered]

If you are really going to have over 700 hp then you should go with a Ricardo transaxle or other like setup.

[alipendier]

Originally Posted by Lobo1186

1) not sure what you mean.

Thanks for the info, but what I was referring to is when doing an engine swap I believe the gear ratios should be close to the stock tranny that the engine came from... So in this case I was wondering if someone knew whether the gear ratios for the Porsche tiptronic are close to those from the stock 1989 BMW 750IL.

I am aware of some people that already mated the BMW V12 to the Audi Tiptronic (Actually it was removed from a 2001 VW Passat), I just dont know which is the stronger tranny between the Audi and the Boxster...


Also why would the Boxster stock not handle that much power, and what do you think the max power it can handle?

[Lobo1186]

Well. as far as the gearing ratio is concerned seeing as the 750 motor comes out of a 4spd auto that will tell you something compared to the tip.

now as far as how much the boxster tranny can hold. I honestly am not sure but give a call to the guys at GBOX they if anyone will know. I believe they told me that their specially treated race tranny could hold like 650 or something. and to me if theirs is an upgraded stock boxster tranny I don't see how the stock could handle more than that. to be honest I cant imagine a passat tranny holding up to 700hp either.

it will be an undertaking to be sure. now how will you fit this motor? being Monocoque is there really a way to expand the engine compartment in a feasible way?

[alipendier]

So are the gear ratios close?

Thanks for the info on GBOX, I will shoot them an email...

The rear of the car would be stretched to fit the motor, I am aware of someone that already fitted the motor but to an audi tiptronic (which s even longer than the Porsche tranny) as I mentioned earlier...

Appreciate it, and I will post info from GBOX

[landrovered]

You are going to have a long and painful learning experience here. Mark these words...NO VW PASSAT GEARBOX WILL SURVIVE 700HP

There is a lot of good info in the kit car world about high HP gearbox options. You might be able to use an inverted G50/20 or G50/50 Porsche gearbox but my money says you will need a ricardo transaxle or other racing gearbox and you will not be able to find an automatic you will end up with a six speed sequential unless you want to spend upwards of $25k.