Well after yesterday's blog, I decided to dive deeper into the GT3 RS at work. When all the modifications are complete, this thing will be (in all honesty) a track monster. The GT3 is an already capable car at any course and the GT3 RS is even more "balls to the wall." However, this costumer is taking it to the extreme (say it like the bro-punks from "Harold & Kumar") with new coil-overs, a sequential shifter adapter, solid spherical control arm bushings (which replaces shitty factory rubber filled ones), "dry" carbon hood & fenders (the real carbon fiber, not your Import Tuner style fiberglass wet-lay), lexan rear quarter panels and rear windshield, an aluminum flywheel, a multi-plate clutch (which is comparably smaller in diameter than the stock friction plates) and a new final drive. So the owner is pretty much taking a bad ass super car and making it more bad ass by reducing weight and rotational mass while improving the cornering capabilities of the car.
Our main topic today is the transmission. As stated before the final drive was changed for a larger ratio (3.9 to 4.1 I believe) which does reduce the top speed, but in all fairness for quicker acceleration off the line and out of the corner. So lets take a look.
At first glance, anyone can notice the use of fins all along the transmission. They act as gussets reducing the effect of torsional loads (especially from drivers who think they can drive, but in reality, can't) and strengthen up the transmission. This allows for the a smaller amount of aluminum to be use (as in our case, this whole thing is made up of cast-aluminum, but not the gears...dummy). These fins also dissipate heat which allows for a more constant oil viscosity reducing the heat and wear experienced by the gears. To me, this transmission looks beautiful like a piece of art, but unlike the indie art shows I've gone to, this art has a function and purpose.
The major thing that separates this from any other Porsche transmission or 99% of other manual transmissions out there is the built in oil cooler. As you can see in the picture above and in the 2nd picture from the top (where it sits right of the transmission), an aluminum box cools down the gear oil that runs through it. In the transmission sits a small mechanical pump (no electronics here) that runs off another gear and shaft in the transmission. It then runs through this small heat exchanger dissipating heat into the atomosphere. But wait, why are there entries and exits on the aluminum heat exchanger? Porsche, knowing full well that the ambient air will cool down this transmission's temperature (which is in excess of 200 Celsius), knew that coolant would act as a better heat absorper than air. Let's think about this for a second. Your coventional rotating heat lamp will keep your lonely-ass slightly warm in a cold room only when it points at you, however, a hot bath will keep you warm for hours, even when the skin-scathing water is turned off. Water (which is largely what coolant is) absorbs heat well and with a kick-ass cooling system like the one on the GT3 RS with its multiplte radiators and aluminum pipes, dissipates heat extremely well. So these entry ports (right of my hand, covered by a blue towel in the picture above) allows coolant to travel through this aluminum box, cooling down gear oil temps. Genius! What's more to say is that the system is simple, effective, and doesn't rely on the use of electronics (oil temp sensors, electric pumps, etc.) which, come on lets face it, will break sooner than its mechanical counterpart or will become hazardous when the system no longer has power. Well after getting excited about a transmission out of a nearly $200,000 car with almost $100,000 invested into it, it's time I face reality which has come through a leaky refridgerator and a $375 asking price to fix it.
Cheers,
-Josh
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