How do you best "launch" a 911 off the line?

[Hendog]

I'm a relatively new owner (4 mos) of my first Porsche 911 (1987 Carrera). DISCLAMER: "I know quite well that the strength of these cars over the others are their abilities in the corners and if I want to go fast in a straight line I should buy a muscle car." I am joining the local PCA for the opportunities of autocrossing which will be more in line with the character of the car. Nonetheless, for the sake of curiosity, I would like to take my car to a local strip/track and see what it is capable of doing 0-60 and quarter mile at least once. Now, I'm not a seasoned racer by any means, but I would like to get the best results from my car that I, as the driver, can obtain. The limitations to good results will be the driver and not the car. Is it really as simple and brutal as bringing the revs up high and popping the clutch? I cringe at the thought of the stress on the clutch plates! What is the best technical method to get a good launch?

[widebody911]

I launch about 2500RPM, which gets you moving well without too much damage to the h/w. Some people, maybe Juan Ruiz, like to launch a little higher, say 6500RPM

[juan ruiz]

This one is going to be a very interesting thread............

[Hendog]

I just noticed a "Autocross and Racing" forum under related forums. I should have perhaps posted there. Can the moderator move this thread; this really isn't a technical question...

[anthony]

I've done a few autocrosses and the launch has never been a big deal. Usually you start well back from the timing lights so you have "free" time to get up to speed.

[kach22i]

Is that my clutch I smell burning?

[vash]

i think getting the car into second fast will be equally scary.

[masraum]

If I want to launch quickly I would prefer to wear the clutch more that hammer the drivetrain, so I would rev it up and bring the clutch out quickly, but not really "pop" it. That way you'll not shock the system too much, but you should still be able to get a decent launch. I think in a 3.2 to get a good launch you'll want to rev higher than 2500, more like 3500 or 4500 depending upon how much traction you're getting with your tires.

With a G50 car second gear can be done the way it would in a 60's Chevy, leave the throttle on the floor and shift as fast as you can. You shouldn't get any grinding but you will likely get a good chirp or even a hop or two depending upon how fast you are.

I only tried a hard launch twice in my old '88, and only shifted hard into 2nd a few times (<5). In my car if the revs were too high or I let the clutch out too fast I got horrible wheel hop.

[Gene-o]

Steam catapult! Older hydraulic ones won't get you moving fast enough and then you'll probably get run over by the ship.

[porcupine911]

Originally posted by anthony
I've done a few autocrosses and the launch has never been a big deal. Usually you start well back from the timing lights so you have "free" time to get up to speed.

ProSolo autocross events have a drag race style launch. they can (and do) wreak havok on drivetrains. i broke the diff on a miata once. i also did a pro in an s2000 where i had to sidestep the clutch at 6500 rpm to keep the car on the high lift vtec cam. fun stuff.

[Hendog]

Masraum, thanks for the help. That sounds like a decent approach. I never considered leaving the gas floored for 2nd gear; as you say I had better be quick on the shift.

[JonT]

The rpm rev before the clutch release is dependent on the amount of traction you are getting with your tires. The perfect launch would spin the tires slightly, keep the revs up in the powerband (over 3500 rpms) to avoid bogging down, and minimize wheel hop. My guess with a 3.2 would be around 3500-4000 rpm with a gradual release (.5 sec) of the clutch vs a quick release.

[Randy Webb]

best way to launch is to have a big-block vette or viper behind to help push....

[beepbeep]

Hey, you're not the only one who drag-raced a 911
Just keep the revs around 4500, pop the clutch pretty quickly and floor the accellerator. Shift to 2:nd around 6500RPM.
911:s launch quite good beacuse of rear weight distribution, only problem is axle hopping. I know a guy who did quite nice starts with almost original 911 Carrera -87 (a car that got lot's of publicity later on 'couse of some getaway movies )

Don't worry, It won't explode. If you smell a burning clutch, it's time to tkae it easy though ;-)

[Shaun @ Tru6]

If you really want to launch quickly, the first thing you do is write a check for $1500 to your garage and place it on the dash, next to that place your AAA card, then it's just a matter of...

[pwd72s]

Hey guys...it's okay! Hendog has one of those new and bulletproof transmissions. We with inferior 915 gearboxes should stay out of this one. I'm anxiously waiting to read of the E.T.'s...

[Hendog]

Thanks for the feed back all. I'll know better after Friday night how to handle this one. Just as a note, the PO added a chip (don't know what kind yet), SSI heat exchangers, B&B muffler, 17 inch wheels. I've got 1500 Km (1000 miles) on new Falken 255/40/17 on the rear, 215/50/17 front. So there's a few extra ponies and some relatively scrubbed-in new rubber to try out. The evening allows for 5 or 6 runs, so it'll be fun. I'll heed BeeBeep's caution and keep my nose tuned for the burning clutch scent. I think the hardware will hold up, it just turned over to 57000 Kilometers. Now if I can just keep focused when it counts...

[724doorE]

Yes, if you even attempt to spin the tires and launch hard our beautiful cars will all explode!!!! Oh the trans just can't take any abuse at all, You really should shift around 2500 or so to be safe. You don't have a roll bar in there do ya, boy that'll spell trouble as well. We have a guy here that does that stuff all the time and whew, I just don't know..... It just won't work. Ask Thrown Hammer, He'll tell ya

[9Firty]

Hendog,

interesting timing of this thread ... I've got a 1984 911 Turbo modified to approx. 370 hp that I took to the drags on the weekend with the local Porsche club. Just supposed to be a bit of fun and like you I was curious about how my car would perform and how to properly get it off the line. However I was also suspect about my clutch going in ... pretty sure it was close to needing to be replaced anyway. Well sure enough on the first run (with the red mist well and truly descended) I've dialled up about +5000 revs to try and get the thing on boost off the line and dumped the clutch ...

Suffice to say that about a third of the way down the straight I'm in 2nd, only doing about 50mph but spinning at +6000rpm and the cabin is starting to fill up with a strange burnt asparagus smell! It ended up gripping but that was basically the end of my day! I tried to do two more runs but by the third I was in danger of doing some serious damage so it was game over. The car is now in the local shop today having a new clutch fitted and I'm going in later for a wallet-ectomy.

I think like you said before, these cars are built to go around corners fast and whilst it's fun and interesting to see what they can do in other areas, don't lose sight of the bigger picture and if you do, don't forget your cheque book!

Cheers

[A Quiet Boom]

OK, I'll add my $0.02. A "perfect" launch at a dragstrip is one in which the tires just barely spin and the engine does not overrev or bog but stays right in the powerband. With my 3.0 hooked to a 901 I've launched hard on the concrete at work (haven't taken it to the track yet) The best launch seems to be up around 4-5k with a fast release of the clutch, not the standard "pop" this allows the suspension to settle in nicely and plant the tires hard. Having drag raced an old Top loader Ford fo many years I suggest the "kick" method for 2nd and 3rd. Just kick the clutch about halfway really quick while you shift at the same time. This is marginally easier on the tranny as well as less likely to cause a missed shift. A lot will depend on your rear tires including PSI and compound but pick an RPM where the car just pulls without spinning or bogging down. It usually easier to start at a higher RPM and work down form there. Pay very close attention to your 60' times since these are the best indicator of a good launch. Also do not deep stage the car since 911 have a pretty decent mechanical reaction time and deep staging could cause a red light. Most tracks have a "test and tune" night, take it to one of those and get the launch perfect before flogging the engine and trans all the way down the course.

If bell and I can even get our act together we paln to head to the strip for a few passes, I'll have to report back our "findings"