Boxster S gearbox

[andygtt]

Hi All

I sold my Boxster S many years ago, always loved the gearbox... anyhow Ive been doing research into a project Im planning to build a mid engine car with a BMW V10 in the back and a porsche gearbox.

Now I have a 996GT3 cup racer box in the garage and a 996 GT2 box both of which would be great on the M5 engine... however they are big money boxes and I have them for other projects so would have to replace them....

In my research I have found someone putting the V10 in the back of a lotus exile and they have used a Boxster S gearbox... this gets me to the point as this box would be perfect for me, I know its a sweat gear change and its actually the right way up to start with (I have to invert the 911 gearboxes, not an issue but leave less room for sump) and its a much much cheaper box.

So how much torque has the Boxster S gearbox been reliable to... can it take 390ftlb and 500bhp at 8500rpm?... my booster S was 252bhp and similar torque seems a big jump but then Ive run 500ftlb in an old 4 speed 911 box made for a car with similar power to the booster S.

Any feedback or links would be appreciated

[andygtt]

noone986s said:

I can't really comment on the transmission's ability to handle the extra torque but....

I run mine with Millers transmission fluid and the shift has been much smoother, especially when cold. As you may remember they are occasionaly a bit difficult until warm. I have 278lb/ft 290hp from mine so half of what you are planning. I also run a Carbonetic LSD, this made a great improvement to getting the power down and there are a few other LSD options now, when I did it, things like the Quaife were not yet available.

Renegade hybrids in the US are running LSx engines in the Boxster now and claim that the transmission can take it, I don't think they add any extra oil cooling or anything to make this happen. Maybe worth a call/email to them too?

I believe that the Audi 01E box is very similar/the same as the Boxster one and are even cheaper. I looked at using one of these for another mid engine project a while ago, might be worth a quick look

This is excellent information thanks

If your running 278ftlb then you are only 100ftlb less than the 5L V10 engine as its the torque that would kill it... and if they are running LS engines on it now without issue then they are all running over 400flb so higher than what I will (amazed an LS would fit in a booster engine bay tbh)

All sounds like good news and shows this is certainly a very viable option.... not sure about the Audi option, quick search seemed that they were around £1k and the Boxster S ones are from £500 which is pretty much a bargain imo.

[andygtt]

I still haven't decided... often boxes are actually a lot stronger than people think... my current mid engine car has over 700bhp and 600ftlb and I am still using the ford mondeo box (designed for 230ftlb) no real mods other than a quaife LSD and multi plate clutch, I abuse the car on road and track for many years and I've not broken it yet which is surprising.

Here is a vid link to show the kind of abuse it gets.

https://www.youtube.com/watch?v=d-23Wdq4etU


What i was looking to find out is if its a known weak box or if people had run it on high torque applications... of cause my car will be lighter than the booster which helps a box take more power than spec'd for.

Edited by andygtt on Friday 19th December 09:22

[andygtt]

worth mentioning, the reason a boxster box would actually be desirable as its designed for mid engine (i.e. box behind the engine).... the 911 box is designed to fit in front of the engine so in order to run it mid engine I would have to run it upside down (otherwise i would have 6 reverse gears lol).