TonyG

Here's some interesting math (this isn't clear cut and there are some approximations made here....)

At WSIR, using 3/4/5 gears, there are 6 gear changes. Each one costing 3/4 car length (against a no-lift 997 Cup Car). That's typically what I see when I race against them.

10.5' per shift (the car is 14' long), x 6 shifts per lap, = 63' per lap lost

63'x12 laps=756' lost per race or approx 1/8th mile back, apples-to-apples, at the end of a 12 lap race.


Even if you say 1/2 a car length per shift

7'x6 shifts per lap = 42' per lap lost
42'x12 laps = 504' lost at the end of the race to the guy with the sequential box.

Go to a track with more shifting and the difference gets worse.

That alone is why you have to go to a sequential box it if you race against people that have them.

Sucks really... they should ban them in the interest of lowering the cost of the sport... but that's never gonna happen with they come stock in factory race cars.

TonyG

George D

Awesome Tony. Neat build. Congratulations!

G

333pg333

Oh sure. Without doubt! These things are awesome. Even more with the paddle shift. Even, even more with a turbo car as you don't lose boost/spool like an H pattern. I am allowed to run an SQ box but no paddles. Problem is that this conversion is out of my budget. So we're stuck with the H pattern 6 speed which is so clunky by comparison. Hence, the less gearchanges the better for us. Hence offset grind 16v build to increase tq. All about compromises unfortunately. I understand you're working on an interesting side project too. Are you chasing anything apart from a weight loss with that?

Duke

Will you be using their pneumatic blipper on the throttle wire?

TonyG

Yes... I'm going to try it out. If it's not reliable, I'll do a linkage direct to the throttle body (which is more work to do).

TonyG

Duke

I use that blipper in my Geartronics setup. It is reliable so far but I haven't got the downshifts perfectly setup yet. To get the very best rev matching the best solution would be e.g. a Motec ECU with DBW throttle integrated with the Geartronics.

thingo

I use the motec and dbw, but these systems take a bit of tuning to get just right.

Duke

It sure does. The more features the more tuning required. I suspect that you run everything related to the paddelshift from the Motec?

The flat shifts are super quick to setup but the downshifts are truly the hard part to tune in.

odurandina

Killer video T.

TonyG

What ECU are you using? And what method are you using to unload the engine for the shifts?

TonyG

Duke

Link G4+ Xtreme. Closed loop ignition cut, the GCU sends the cut signal to the ECU which cuts the ignition for as long as the signal is active. You can adjust some settings in the ECU for the re-introduction of ignition to smooth it out if necessary.

Here's an in-car clip:

Duke

Here's the same clip but with rpm, speedo and gear number. Easier to understand the shifts on this video

333pg333

I hate you all....


....in the nicest possible way.

disasterman

Ditto Patrick's sentiments. I have the same issue racing against 997 cups.

951and944S

These kind of mods are pretty much out of most people's league but it's interesting to see fully developed cars like the latest contributors on this last page of the thread.

We race PCA, so unless you are building up an all out GT car, class rules would not allow aftermarket transmissions, and while I really have no reason to investigate this avenue for SP2 and SP3 cars that we race, it made me wonder,

1) In a PCA GT car, you could probably get away with a PDK transmission as it would be "factory Porsche gearbox".

2) Following Tony's links to the pneumatic shifter setup and the transmission itself, by the time you start adding up all the necessary hardware, sorting out the software (as Duke stated)....would it not be possible (and way less expensive) to just find donor parts from salvaged Caymans and just adapt this transmission...?

I was in the transmission business for 25 years, so naturally, when the PDK arrived on the scene, I was curious enough to read as much as I could, although at the time, not much information about internals was out there (probably due to proprietary reasons) and the factory was the only way to get a unit either repaired or refreshed was through a factory exchange program.

When you hear the PCA class Caymans with PDK pass by on track, the gear change speed is unbelievable and it, by design, should be even faster than any pneumatically shifted conventional gearbox, since by design, if I understand correctly by the limited information available at the time, the next gear is already engaged before it's actually selected by the use of twin input shafts (PDK = Porsche double coupling).

T. Simon