kmagnuss

Dang that's awesome.

oemexp

I forgot to mention that the motors in these cars have been put on a serious diet by Porsche. The gear box is heavier than a street non-GT3 996 and the engine may also be heavier than a non-GT3 motor. However, Porsche went with very thin castings for the water management on the RSR (much lighter than the previous GT3 race cars such as the R and RS). These also have 5lb Inconel headers and a $5K McLaren built 200A alternator that looks like a 40A toy alternator that comes on a civic. Unrestricted, the car puts out 540hp so the drive line has to be kind of heavy to be tough enough to handle that in endurance racing. In all, I think you can get a street car down pretty light if you start removing things and throwing them in "to be used for the restoration later" storage shed.

jrgordonsenior

FWIW.... My latest 996 is a 03' X51 sunroof delete(steel skin) and weighs 2,500 empty, about 75lb. more than my 99' 996. Nothing much different between the 2 cars except the 03' has a chromoly cage vs. the DOM cage in the 99' car. The 99's were just lighter to begin with....

onefastviking

It had to do with the tub or chassis itself, they used more steel reinforcements in the later years to increase torsional rigidity. The even used different types of steels in places to step up the rigidity.
I have the documents that PORSCHE put out that goes over the improvements. It was a big help for the street cars to feel more solid, be quieter, and handle better.
That extra rigid chassis came at the expense of a little more weight. In reality, if you did your cage correctly then that factory extra steel won't help the chassis any because the cage will be doing a much more serious job of adding rigidness.

Let me know if you really want to know more JR., if so I will try to dig up the documents from PORSCHE that explain it in greater detail.

Btw, as I remember it your 99 had a 1.5" and pretty bare bones cage, correct ?
I'm guessing this 2003 car handles much differently than the 99, can you feel the difference ? I know there are numerous other changes as well so it might be hard to tell.

jj1

I've always been under the impression that even with a full cage tied into the suspension pick ups, that the chassis inherent rigidity is still important. Basically even with a well built cage it's not good to shed weight at the expense of weakening the chassis.

onefastviking

True, but a well built cage will do more than PORSCHE did with their additional metal.

jj1

Absolutely agreed.

VOLTCONTROL

Interesting tips in this (old) thread!
You might also want to be aware of this build thread as it contains some interesting bits including lots of details and pictures of a CF roof conversion, a custom built steering rack and much more:

The 996 CLR (after his avatar CarreraLightweightRacing)
Intro to the build: https://www.pistonheads.com/gassing/...f=48&t=1604071
Build Thread: http://911uk.com/viewtopic.php?t=106137

tdcurtner

Threads like this just can never die! They shouldn't. New ones often end up quoting or linking to the old ones.