Maybe it's not true with Porsche, but I've always considered the tranny to be the weakest link in any car. That being said, I am very weary of "chipping" the tranny. I would be concerned about too many hard shifts and the like.

BTW, I'd like to agree with AS about the shift patterns adapting VERY quickly. In fact last night I was tooling around town and decided that I wanted to have some fun and within a mile or 2 it was already holding gears without upshifting!

 

Jeff,
I think you're quite right. I remember seeing one tuner evaluation in Car and Driver (I think) about 2 years ago. Like most independent reviews, there was very little to no performance gains to be had from engine ECU upgrades (turbos excepted). On the other hand, they DID get some pretty good improvements in the automatic transmission cars they tested after upgrades to speed up shifting.

Andy

 

Talking about shifting at redline...isn't that too high for max performance? Doesn't torque band fade before redline, so wouldn't peak torque be the better shift point.
(I'm no expert, but I play one on the Forums )

 

Trojan...
I'd say just the opposite - in most (but not all) cars, the auto trans is the "strongest" link - much greater Torque forces than in an equivelent "stick". As far as the Porsche units, there's a good deal of cooling going on - and that' s usually the weakest link in auto trannys (more shifting = more fluid movement/pressure = more heat). In my own (very limited, to be sure) experience, the trans fluid has held up well under some serious abuse (whoops - did I just type that outloud??? Ok, no abuse - just hard use, OK?)
You're spot on about the Tip adapting quickly, though. I don't have my data handy, but the Tip "adjusts" according to some 270+ "maps" utilizing a great deal of real time data, thus "learning" occurs within seconds. Older Tips (pre 2000, I think) used 5 maps and "collected" data over a period of time - taking up to several minutes to "change" modes. (sorry for being vague on the numbers/dates - I'm away from my desk/references)
Andy,
Now you mention it, I too recall such an article. Have to do some digging....
J

 

Don-W, I don't think so. Why would F1 cars shift at 19,000? Those cars make very little torque, but their high power is related to the amount of air and fuel consumed which is higher the faster the engine spins. The exceptions are cars like the early C4 Corvettes which made peak power at low rpm's (less than 5,000) by by recollection and were fastest if shifted at 4000.
When I was racing a Can Am Lola in vintage, I asked my engine builder (Earl Gaerty of sprint car fame) where I should shift with an engine that made max hp at 6,800. Gaerte's advice was to take it past the peak power point (he suggested 7200) so the upshift brought you to just below peak hp after the shift. I continue to find that advice works well. In our cars (mine is an X50tt), I've found you just don't want to hit the rev limiter-that definitely seems slower. AS

 

Stem, your points are irrefutable, especially from me. It certainly makes sense.

 

Alexander...I found, as you have, that the "shift" while the suspension is loaded is one of the more remarkable things the Tip does. I like a six speed fine, but I ( and I don't think it is just me) don't get a lot of control out of the car when I shift in a hard turn!

 

Wow! It keeps going and going...I didn't realize the 'popularity' of my post.

 

Stem,
You're advice is spot on - roughly go to the point in the HP curve above the peak so that when the upshift is completed you are at (or near) the torque peak (Paul Frere's excellent "Sports Car & Competition Driving" has the math to back it up).
Great thread, not - a! ( but that avatar keeps reminding me I'm lactose intolerant.....)
J

 

Alexander,

I wasn't aware of this "rule", thought it makes sense. I'll have to try it (on someone else's car).

However, isn't the 19K shift point for an F1 engine a function of a max displacement restriction (3 liters)? It seems that w/ each manufacturer's latest spec engine, they're squeezing a few hundred more RPM's out of it, as it's the only place left to go for more power. At Indy, Honda had their latest-spec engine turning ~19.5K, yet both BAR's grenaded if I remember correctly!

BTW, I drove my first Porsche tip yesterday, in a C2. I plan to drive a Turbo tip today (car shopping for my wife, who doesn't like manuals). I'm sure I'll have a full report.

Thanks, all, for the interesting and informative thread.

-DT