[STI_4U2NV]

I would like to know the best way to launch your STI; Revs and Clutch. I have heard it is best to practice on wet pavement. Any help or techniques would be greatly appreciated.

[rob142sti]

im not expert but make sure your tires are inflated to around 40psi
mine were at 30 and i bogged pretty bad and couldnt break the tires free the entire night

[jays05]

I love these threads, since launching IMO is the best thing about this car. I run low 40's up front and high 30's in back for tire pressure. Right now it is 42F/39R. I blip the throttle between 5-6k at the line and do a slight slip of the clutch around 5500. I aim to get the clutch out at 4000rpms as soon as possible. It should be a slight bog. The slight bog loads the engine really well, and gets you out of the hole at torque peak with a nice boost spike. For DCCD settings I run with it in Manual/Open (all the way to the back). That gave me slightly better 60-ft times than running in Auto and knocked about two tenths off my ET. I can cut consistent 1.6x 60-ft times if there is enough traction on the track. I wouldn't practice on wet pavement though - too much wheelspin/wheelhop.

[Allen504tke]

Nice - Subscribed

[avengermike]

now i launch at the same rpms but i have the DCCD in lock, i have tried locked and full rear and cant get off the line fast enough in rear. Auto just kills my car she falls on her face, how bad is it to do with her in lock will it hurt anything?

[sciolist]

It sounds like most of you are launching for drag racing, which I guess allows the option of manual DCCD settings. Otherwise, I would use AUTO. You might drop a few 1/100's on the launch, but you'll gain numerous 1/10's back as soon as you start turning the car.

The idea is to go from a state of rest to a state of maximum acceleration in the smallest possible period of time. Obviously maximum acceleration requires maximum traction, so it might make sense to learn to launch with something close to optimum inflation pressures.

Once the pressures and DCCD setting are settled on, it seems to me that there are three remaining variables: Slip at the clutch, slip at the tire and engine speed. You want to increase the rate of wheel speed as quickly as possible, but the wheels have to be pushing the car forward, so you can't give up much traction. OTOH, you have to give some up to get some back.

Try a launch with equal balance between throttle and clutch: You'll bog. Try revving to 6K and letting the clutch out real fast: You'll spin. Try breaking traction and letting the clutch out nice and slow to get it back: You'll make a nasty smell and wear down the plate a bit.

A good launch will balance all of that into one equitable equation. Rev high enough so that you have adequate engine speed to just barely break traction. Engage the clutch slowly enough to buffer the transfer of power, but fast enough to get the tires loose at their optimal inflation pressure. The balance is going to vary depending on pavement surface, temperature, humidity (or outright wetness) and obviously the car's mod's.

My experience suggests it's easier to start out a little hot and cool your way down to a close-to-perfect balance. If you start to over-spin when it matters, you can give up a little clutch to get it back. If you come off the line too cool, you can slow up the engagement and put in some more throttle. There's not going to be a single prescriptive method that works for all conditions. The key, just like with cornering, is to be sensitive to what's going on and to be able to adapt intuitively in a very short period of time - that's what's going to make you faster than the other guy.

[Illusive]

Originally Posted by jaygoesfast

I love these threads, since launching IMO is the best thing about this car. I run low 40's up front and high 30's in back for tire pressure. Right now it is 42F/39R. I blip the throttle between 5-6k at the line and do a slight slip of the clutch around 5500. I aim to get the clutch out at 4000rpms as soon as possible. It should be a slight bog. The slight bog loads the engine really well, and gets you out of the hole at torque peak with a nice boost spike. For DCCD settings I run with it in Manual/Open (all the way to the back). That gave me slightly better 60-ft times than running in Auto and knocked about two tenths off my ET. I can cut consistent 1.6x 60-ft times if there is enough traction on the track. I wouldn't practice on wet pavement though - too much wheelspin/wheelhop.

gonna have to try that a 1.6 60' would bump me into low 8.1's

best so far was 1.705. hopefully I can test it out this thursday at irwindale.

[jays05]

My own experience with the DCCD settings was that I did 50+ runs with the DCCD in Auto (and a couple times in lock) and ran a best ET of 12.92. I went back to the track one day and did my first run with the DCCD in lock and ran a 13.02. I put it in Manual/Open and ran a 12.79 6 minutes later (hardly anybody showed up at the track that day). I did three more 12.8x runs that day, and after a couple more visits to the track I had my time down to a 12.62. It seems like running in Manual/Open has less parasitic drag on the drivetrain, but I have nothing to base that off besides my quarter mile times.

[Illusive]

Originally Posted by jaygoesfast

My own experience with the DCCD settings was that I did 50+ runs with the DCCD in Auto (and a couple times in lock) and ran a best ET of 12.92. I went back to the track one day and did my first run with the DCCD in lock and ran a 13.02. I put it in Manual/Open and ran a 12.79 6 minutes later (hardly anybody showed up at the track that day). I did three more 12.8x runs that day, and after a couple more visits to the track I had my time down to a 12.62. It seems like running in Manual/Open has less parasitic drag on the drivetrain, but I have nothing to base that off besides my quarter mile times.

thats an interesting theory, have any trap speed numbers that could substaitate that? like going from average 106 to 107's?

without those numbers simply reducing your 60' by 1 tenth can drop your 1/4 by 1.5-2 tenths. if you were doing 1.7's with diff in auto, and 1.6's consistantly with diff in manual open full rear, that "could" explain the drop in et's

but again with out trap speeds its hard to say the 60' was the only factor, weather, altitude density, & driver factor into the equation also.

[jays05]

I'll post my whole quarter mile log when I'm at work tomorrow (about 70 quarter mile passes). I have it in ms excel and it should copy-paste just fine here. The difference is pretty noticable when you look at the times all together. My quarter mile trap increased a little... the eighth mile trap increased more. I was cutting 1.6x 60's before but not nearly as consistently.

I'll probably be heading to the dragstrip again tomorrow evening, maybe I'll make a few different passes with different DCCD settings and see how it goes.

[Illusive]

Originally Posted by jaygoesfast

I'll post my whole quarter mile log when I'm at work tomorrow (about 70 quarter mile passes). I have it in ms excel and it should copy-paste just fine here. The difference is pretty noticable when you look at the times all together. My quarter mile trap increased a little... the eighth mile trap increased more. I was cutting 1.6x 60's before but not nearly as consistently.

I'll probably be heading to the dragstrip again tomorrow evening, maybe I'll make a few different passes with different DCCD settings and see how it goes.

awesome thats a nice library of info. eagerly awaiting.

I'd also like to compare against my 1/8 runs to yours too.

i'm going again wingless on thursday to irwindale, and going to run on race fuel, I'd like to see if there is a noticable difference, there wasn't one with race fuel and stock, so I'd like to see if modded + race fuel+ wingless could push me into 84mph traps and into 8.1's

i'm also going to play with the dccd too and put it on full rear to try to squeeze out a better 60' like you suggested.

[garrettjj]

Very good times on the Stock turbo Jay! Pushing 110 on trap speeds too. Thumbs up.
I'm going to try adjusting the tires pressure to what you mentioned to see if it makes a difference seeing you have quite a few passes under your belt.

[polishsti]

I have heard from professional rallye drivers that the right way to launch a awd car is to drop cluch as soon as possible on low rpm's and then accelerate without the clutch.

I can't really imagine launching with reving up and dropping the clutch without burning it.
I dont want to burn my clutch it smells bad.

[BluSTi]

I've auto-xed a few times this summer, maybe 15 or 20 starts, and my favority way to launch is to hit the rev limiter for a tick, drop the clutch, and hold on. I've had very little wheel spin and very good acceleration at the time. I'm at 4500' with 91 octane, dccd on auto, and stock tires, but the acceleration made my dad curse when I took him for a ride. He has an '87 Porsche 930 with an andial stage 1 or 2 kit in it, I'm not sure. He was impressed. Try it.

[Illusive]

okay I went and did some testing at LACR. in case any of you know its a crummy track, THE slowest in so cal. elevation is 2700 ft above sea level temps were mid 80's the whole night and you could smell the ash in the air from the fires.

I went wingless too. I made 3 passes with the dccd in auto, then 3 with it in full rear.

I dont have the full slip but I remember the 1/4 1/8 and mph's

first pass was 13.6 @98.2mph with 1.79 60' and 8.6 1/8
next pass was 13.5 @ 98.4mph with 1.80 60' and 8.6 1/8
final auto dccd was 13.5 @ 98.5 mph with 1.78 60' and 8.59 1/8

switched to full rear dccd 13.4 @ 100.1mph with 1.75 60' and 8.52 1/8
next pass 13.5 @ 100.01 mph with 1.76 60' and 8.55 1/8
last pass was 13.7 @ 99.9 mph with 1.90 60' and 8.7 1/8 (wasn't paying attention to the tree and since it's bracket racing and ET counts I hurried the launch and bogged off the line)

so far with dccd in full rear it picked up about 1.5 mph in my 1/4 traps, I remember my 1/8 mhp traps were still consistantly the same at 79.9 or 80.0 mph. with it in either auto or full rear. but the 1/4 made the biggest difference.