Drag strip advice needed!

spence88mph · 07-07-2010, 01:26 AM

So my friends are all going down to the strip this friday night and I think I might see what my car will run over the quarter without really launching it too hard. I have been told to reduce the pressure of the rear tyres to about 20psi and just go for it!

I was thinking of removing the spare, toolkit and possibly the passenger seat as they weigh a tonne but I don't think I'll bother with the seat unless you guys think it's worth it?

The car is an '89 3.2 Carrera with Protomotive stage (claimed 360chp at .5 bar, no intercooler), it will be a very cold night, any idea what the car could run? I'm thinking low 13s, high 12s and I would be stoked! who knows, any advice to get a good time?

smurfbus · 07-07-2010, 01:48 AM

If you're going to take it easy on the launch there is no point getting the tire pressures down unless you have traction issues on lower gears. Just leave the seat so it's more like every day driver timesplip. Get the tank level low and pump the best fuel you can get (some booster if you like) about 1/4 tank.

Depending on your torque curve choose the shiftpoints so that you use the best possible area under the curve considering the torque to the wheels.

Having a G-meter would be helpfull. One run in every gear and then put the runs on the same exel sheet with mph at the x-axis and accel at the y-axis. Then look at where the acceleration crosses between the gears. That point is pretty close to optimum shifting mph. If there is no crossing then it would be best to run to the rev limit.

The ET is a lot about the launch and the mph is more about power to the ground. So if you are after the ET you will benefit the most of a good launch.

This IMO, others may shime in with better advice.

billjam · billjam's Garage

You will really enjoy this. Our club did a run at the drag strip in Perth last year and it was a real ball. The track surface is really amazing - looks like rubber!
Don't expect any wheel spin.

Just go easy on the launch if you want more than one run. A standard clutch really doesn't like this sort of treatment (just ask ... !)
What worked best for me was to just get it rolling without too much clutch slip, then just wait for the boost to click in. Seems like an eternity, but at least you'll be able to drive home

WinRice · 07-07-2010, 12:34 PM

Air your front tires to the maximum for a tad less rolling resistance.

drmatera · 07-07-2010, 03:25 PM

just go have fun...

an easy launch will net a miserable 60' time which will result in a bad 1/4 mile time. As others have said, launch the car as you feel fit and just let it run out the back door.

I cut a 2.01 60' on a pretty aggressive launch in my 930. It went 12.18 @ 118mph running thru the traps in 3rd gear

spence88mph · 07-07-2010, 03:54 PM

Thanks a lot for all the info guys, really looking forward to it, I've done it a couple of times in other cars, never the 911 though as I'm a little scared of killing it! What did you end up running Bill? drmatera, 12.18 is quick, is that in your current state of tune?

billjam · billjam's Garage

Quote:

Originally Posted by spence88mph

Thanks a lot for all the info guys, really looking forward to it, I've done it a couple of times in other cars, never the 911 though as I'm a little scared of killing it! What did you end up running Bill?

Damn! I just knew someone was going to ask that question!!
The staging lights and the timing were all running, but times were only displayed on the trackside screens that you couldn't see from the track - no recording

so I have no idea - low 10's I reckon

It was still a great experience, even without knowing times. You'll have fun.

drmatera · 07-08-2010, 09:05 AM

That was with the K27 and the double stacked stock intercoolers running 16psi of boost. The new turbo / intercooler set-up feels much faster but the weather has been lousy to say the least so no trips to the track on the new combo.

The trick to not breaking stuff is to slip the clutch and don't bang the gears like a super stocker. You will need to leave with some revs but don't just dump the clutch. Being a 3.2 N/A with a turbo you're sure to have much better low end power than our 930's so I don't see why you couldn't cut some 2.00 60' times or maybe better.

If so I'll predict 13.2 @ 110. Are we starting a pool?