Well I was sad when I started to race due to the fact that my first run was a 15.59 @87.94mph. HOWEVER........all was turned around in a split second when I did my very last run of the night against a twin turbo Mazda RX-7 that was running 13.2 qrt's. Keep in mind that this was not the time trials but after all the races were completed, so we started at the same time. I pull up to activate the lights waiting in excitement. I look over and see the fear in his eye's.... when the light turns green I am off like a rocket!! No tire spin what so ever, only the slight chirp of the tires. I am about 3/4 of a car length ahead of him all the way down the track and I cross the finish line with the largest grin on my face since I first bought the car. I BLEW HIM AWAY!!! HA HA HA HA HAAAA....(the man said to me that he had a bad launch) Here are our times:

Lane 1 him:
reaction: 0.592
2.442
6.432
9.640@79.364mph
12.224
E.T.: 14.454@100.652mph

Lane 2 me:
reaction: 0.649
2.472
6.340
9.455@80.473
12.087
E.T.: 14.321@102.454mph:buttrock

If only I could get the 60ft times down I might be in the 13's. What do you guy's think? I need to really practice on my launching.


_pAuL_

Oh yeah! :buttrock

You shave 2 tenths off your 60' time and you will be running 13's! Play with your tire pressures some, practice that launch some more, and you're there!

Yeah, I think that I let too much air out of my tires. I had never done that before but I thought it would help me with traction, it felt like it actually made my launch worse. I had it down to about 24 psi, next time I will run it at 30psi.

Originally posted by pidnaul
Yeah, I think that I let too much air out of my tires. I had never done that before but I thought it would help me with traction, it felt like it actually made my launch worse. I had it down to about 24 psi, next time I will run it at 30psi.


Yeah, letting too much air out can cause cupping which actually hurts performance, I'd go a little lower that 30 psi, I'd prolly do around 28. But if you need help, just ask Dave. He is a track hero. :D

Whatever the mfgr recommended psi is for the rear tires, I'd drop it 4 psi to start, see how you do, the outside temps make a difference too. On OEM tires I usually go 4-6 psi under mfgr specs depending.

For example, if your rear tires are supposed to be at 32 psi, take 'em to 28 psi, then maybe drop them to 27 or 26, see how that effects your 60" times, if it's too low at 26, just make sure you have one of those little pumps with you that plugs into the cig lighter and pump them back up for the next run, etc...

Take notes on all your launches, tape the timeslip to that page in a notebook, take note of temps, psi, launch rpms, shift rpms, etc. Keep it for your records and for future reference.

You can plant your face on the ground and have a friend roll away in your car too to sorta see if you're cupping or not.

On drag radials you can go a lot lower with psi, but they are made with that in mind...

PS- Thanks for the compliment! :)

I went to the drags today with one goal, break into the 13's. And I did it.

R/T .528
60' 2.179
330 5.938
1/8 9.000
MPH 81.63
1000 11.635
1/4 13.867
MPH 101.51

and

R/T .533
60' 5.944
1/8 8.982
MPH 82.28
1000 11.603
1/4 13.819
MPH 103.09
:buttrock
I did two things to the car since last week when I ran a 14.0, new tires and new plugs. And go more aggressive once I knew the tires were gonna get traction!
Now... its time for some pulleys and maybe an intake. Still on the stock exhaust and intake box! But, is this were my car should be, or could I improve more on the driving?

If you can get that 60' time down to a flat even 2.0, you'd be closer to 13.5-13.6. Which you should be able to do in your car.

What size rear tires are you running? What psi was in the rear tires? What psi in the fronts? At what rpm are you launching? Are you hearing any chirp/wheelspin on the shifts?

245/40/17 Michelin Pilots at 30 psi. in the rear, and 50 psi in the front. I reved to about 1700 rpm and road the clutch for a split second, then mashed it, the tires spun for about 3ft. then caught traction, the rpms didn't drop much when I got traction, so I think I did it right?
I've never really gotten a decent launch in my car before so the whole feeling is completely new to me, but it was awesome! Second gear the tires spun a bit, I tried the technique I've heard from you before "squeeze the throttle half way", I went 3/4 of the way, the clutch slipped ever so slightly and slipped again going into both 3rd and 4th. It slipped enough to prevent a chirp/spin, but don't know if it helped or hurt my time. I've had trouble while trying to launch the car on the street, the clutch would slip really bad when shifting out of first and thru the rest of the gears.
I know the power is there, I raced a 99 Carrera on the way home... and stood right on the side of him, I also raced a supercharged NSX, I'll admit he did inch away, but it was honestly only inches...
I've read before that there are optimal shift points to get into the next gears peak torque level. Any idea about these? Does it vary from car to car?

Shift points do vary from car to car, engine to engine, and depend on your gears, etc. The best way to plot shift points is to dyno your car and calculate from there.

I would go 28 psi on 245/40-17's.

Chirping on shifts can cost you a tenth or 2, not chipring is better for ET's.

Sounds like you mashed the gas pedal too much on the launch, you want virtually no wheelspin at all on launch.

Let me dig up an old post on launch tips...

Here you go:

Copy/paste from a thread in the Forced Induction Forum here about 1/4 mile times and launching....

"I do think lowering the psi in your rear tires will make a difference. I don't know what size tires you have, but if you have the stock 245/40-17's in the rear, you want more tires on the road, not less when it comes to the 1/4 mile drag strip for launching.

Now the standard mfgr recommended psi for 245/40-17's is 32 psi. Here's the key, you gotta play with it some. If you go too low you could have cupping, and that doesn't help either.

I'm guessing at 245/40-17's for you, but that is my OEM size too for my car and I have run it at the track with those OEM Dunlops before (I usually run my drag radials at the track...). Anyhow, you're safe dropping them to 28 psi, no problem. You might even be able to go as low as 26 psi, maybe 25 psi, depends on the weather and the track surface temps.

Also, for less friction/rolling resistance, take the front tires up to 45-55 psi.

Also, for weight savings, take as much out of your car as you can. The spare tire and mounting apparatus can weigh as much as 30-40 lbs.

Back seat, passenger seat (my passenger seat weighs like 60 lbs), any excess weight. Take the gas tank down to 1/8th a tank of gas, 1 gallon of gas can weigh like 5 lbs, run a 13-16 gallon tank down to 1/8th a tank, another 50-70 lbs, etc...

You can shave 150-200 lbs with that kind of prep work.

Also, try launching higher. You need to find the sweet spot, between bogging and wheelspin, and that will takes lots of practice and change from day to day, track to track, etc...

The more traction you get from the tires, the higher you can launch your car, and you generally want to launch above torque peak so that when the tires grab, the tach drops, and if you can work the clutch right, avoid major wheelspin, you'll launch like a rocket.

With my DR's I launch at 5500 rpm. On my OEM Dunlops more like 4500-4800 rpm at 26 psi.

Gotta get the throttle steady when staging, an even rpm, clutch half in, half out, just about to grab, the tach dipping ever so slightly.

When the green hits, don't slam your foot down on the gas to the floor, quickly and steadily squeeze it to the floor, and gradually but quickly let out the clutch, sense too much throttle, keep it steadily continually going down and adjust the power to the wheels with the clutch, not the gas.

Now, if when you're shifting you're chirping your tires on every shift, you're losing maybe a tenth. In my car if I'm not careful I could get sideways on every shift, but this method can help anyone chirping on shifts too much:

Find the appropriate amount of throttle to stab back down, then squeeze it to the floor. For me, it's about halfway, then just like on the launch, I quickly squeeze the gas pedal down. I stab halfway (versus all the way back to the floor) and quickly squeeze the pedal back down to the floor. Makes for more uneventful shifts and buys me a couple tenths in the 1/4 mile (I have to shift 3 times, I finish in 4th gear).

Your car may work best with a 2/3rd stab then squeeze, or 3/4th throttle then the quick squeeze, all these techniques require practice and could change given the weather or the track. I take notes on all these items and then tape the timeslip next to it on a notebook page and save it for the future track visits.

Also, if you feel like you're destroying your clutch, you're launching properly if you feel like you preserved some of it, you're not launching right... "


I launch at 5500 rpm, pump my fronts up to 55 psi, rear drag radials down to 16-18 psi, plus all the weight shaving and cool downs in between runs...

Whatever it takes to eek out every last tenth in my car...

Owen what have you done to your M3? 13.8 is pretty impressive!

SilverStreak - I've studied that post numerous times... lol, thanks for providing us with that info. I'm gonna dyno the car hopefully next week, then I'll have to do the calculations, which I'll probably ask for help with also.

Gibba - my car was built before I bought it, unfortunately, so I don't know every detail. But I do know that it has a 3.2L block on OBD1, a Conforti/Tuner chip tuned for a 3.5HFM and 24lb injectors, K&N airfilter in stock box and stock exhaust. I also think it has the 3.0 intake manifold, head and headers.
I'm hoping that a cone-filter/heat shield and exhaust will free up some more power, but before that I'm gonna learn how to drive it to its best!
Ps - thanks for the compliment!

Cool, keep me posted!

Dave you need to make that thread where you give launching tips Sticky...how many times do you think you've copied and pasted that!? :D

Then again...that could cut out some of your posts...:stickoutt

:lol: No kidding, between re-posts and PMs, I've probably copied it 2 dozen times... it's out FAQ for the Z3 Forum too... :D

My buddy uploaded the video of me at the drags... check it out!

http://www.highspeeddubbin.com/movies/drags/Owen.mpg

Very cool! :buttrock