Gents, I just returned from a test drive of my 348 Twin Turbo. I took our club head mechanic with me, to listen and share his thoughts. The goal of our ride was to test and "guess" at the best launch RPM for my car. We figured a minumum of wheel spin and minimum of engine "bog". After a few trys, we figured the best RPM was very close to 4000. For my 348, (with the 355 wheels and Perrelli's), the car had little wheel hop and little spin at clutch release and was just beginning to produce boost, (it makes .5 lbs at 3000 RPM), so the engine acceleration was fast there with little decrease in RPM's upon clutch release. So, is it better to suffer a bit more wheel spin and be MAKING BIG POWER, or leave "as is"? Thanks for your thoughts..............
Every car is different. How long you want the clutch to last is offset by the need for speed. Tire size and pressure also factor in big time in avoiding wheel spin. I take it easy on my Europa since a Lexus can out drag me anyway. 1500 RPM is plenty and smooth as my faux leather seats. My max 0-60 time is acheived at about 3000 RPM. Your mileage WILL vary.
Ken is right about differences car to car of course. I've tried all types of launch rpms with all types of cars. I assume we are talking 1/4 mile launches.My nitrous Viper liked 4500 rpm the 996 TT was best at 4000 rpm. I've found that just lugging it out of the hole is not optimal for good 0-60 times (1.5-1.6 secs). Play with under timed conditions then you will KNOW what works best for your car.
if you have the money and time to spend on clutch replacements, pick up a g-tech pro or a g-tech pro competition. it's a small little tool that will end your guesses regarding slippage on the line and how well the hookup is at a given rpm. that's really the best way to find out besides guessing haphazardly.
I have a Viper club 10 sec hat.(that was the most expensive ballcap I have) 685 RWHP 817 ft/lbs torque www.graduategemologist-gia.com/noseducts.jpg
I launch my turbo WRX @ just over 3000 RPM (that's above turbo-lag range). Then I shift everytime I get it up to 5200 RPM (that's where the torque & hp curves cross). The idea is to get the car up into the highest gear as quickly & "speed-efficiently" as possible. As one goes up in the gears, each 1000 RPM will deliver a higher rise in speed. That's why you would rather spend your time accelerating in higher gears (at above the turbo-lag RPM)
With my street cars I just take off with 1500-2000 rpm. They are plenty quick enough and my clutches last. With my 87 March-Cosworth Indycar....that's another story!!! 6000-8000rpm and dump the clutch is the only way to go! Lot's of wheelspin....lot's of fun and I've not blown a clutch....yet!!!! Ciao....Dino
That's a tough one with a high boost turbo car, but it sounds like you've got it about right. The turbo's don't spool until the throttle is open, so you need to store enough energy in the flywheel to keep the engine from bogging until the turbo is on...but that usually gives you more than the tires can stand when you first let go of the clutch. I ususlly start at a relatively high rpm, work my why down until it bogs, then go back up 200-500 rpm and that's probably the best you're going to do. When I was running my old blower at 10 psi, I found 4000 would usually bog it, 4500 always good, and 5000 always caused massive wheel spin. With the new blower/intercooler turned all the way up, there is no launch rpm that doesn't cause wheel spin, I use 4000 and and keep the boost gage to about 10 psi, 2nd gear 18 psi, and floor it in 3rd. Attitude928 - If you're trying to go fast, you want to shift up near or at redline depending on the gearing, but never below the peak hp point. Torque and hp cross at 5252 by definition of the units used to measure, there is nothing magic about the point.
