Launch recommendations?

[te72]

Guys, probably gonna be taking my car to the track (~200 miles one way) to make a few passes, see what I can do with the current setup:

-stock 1j, filter, intake, intercooler
-ported head
-BC264 cams
-3" exhaust from turbos back
-dyno'd 320whp at 12psi, going to try to track down/make an MBC to get boost to 15-16psi
-Megan Track coilovers, set VERY near as soft as possible in the rear, stiff front
-Nitto NT05, 275/40/17 tires, plan on ~20psi rear, maybe 40psi front

I've launched the car at 5500 on the street on my winter tires, which are significantly less sticky than the Nittos. However, at 6k, this setup lit up pretty bad. I was thinking with the Nittos I could probably launch upwards of 7k without too much wheel spin.

I'm shooting for a 13.1-13.2@105-107ish, at whatever track we're going to in Salt Lake. Elevation is around 4500' IIRC, but I don't think it will suffer much.

If anyone has recommendations (serious recommendations), I'd love to hear them.

 

[RBD 305]

I'm assuming the car is manual trans, what type of clutch setup are you running?

 

[suprahero]

I've never launched my car from that high of an rpm, but only because: A: I'm a sissy and B: I drive my car to the track when I go and I've broken about everything you can break while launching at only 5500rpm. So far I've broken my LSD, my two piece drive shaft, and numerous clutches.

When I had my Nitto 555r's, I wheel hopped horribly. I haven't had that problem since I switched to the Mickey Thompson ET streets. I also never broke anything with the Nitto's. The ET streets hook way better than the Nitto's did.

Good luck with the trip. Take lots and lots of videos and don't forget that sacrificing a virgin to the car gods has never let me down. I still break shit, but there's nothing quite like a virgin........lol

 

[GrimJack]

Street vs Track is going to be hugely different... the VHT compound on tracks will increase the RPM you'll need to hit to avoid bogging.

 

[Turbo Habanero]

My buddy and i went to the track tonight he was on some street radials 245/50/r16 1jz stock twins fully bolted 17psi

Launched at 4500rpm he ran a 13.8 @ 105 anything higher he spun for days.

 

[Suprapowaz!(2)]

When I had my Nitto 555r's, I wheel hopped horribly. I haven't had that problem since I switched to the Mickey Thompson ET streets. I also never broke anything with the Nitto's. The ET streets hook way better than the Nitto's did.

I wish I had gone with ET Streets. I was too cheap though. Nitto 555r's beats regular compound street tires hands down though. When I do launch and get wheelspin, the tires recover quickly, grab, and go. I'm sure ET Streets don't put up with wheelspin.

 

[jotech]

look what i can tell you to do is start whit lets say 25psi in the tires and launch at 3500 or 4500 rpm why it is best to either bog or spin than break and at 25 psi i don't think it will bog it will spin,the second pass lower the psi lets say 22 psi and launch at the same rpm and if you feel it will bog the next pas leave the tires the same pressure and ref her a tab higher and see,do remember to chek your tire pressure every run because the air tends to get hot and it will raise your tire pressure.

 

[te72]

Street vs Track is going to be hugely different... the VHT compound on tracks will increase the RPM you'll need to hit to avoid bogging.

Definitely not worried about bogging, car has never done that. I've always found that sweet spot for the most part...

look what i can tell you to do is start whit lets say 25psi in the tires and launch at 3500 or 4500 rpm why it is best to either bog or spin than break and at 25 psi i don't think it will bog it will spin,the second pass lower the psi lets say 22 psi and launch at the same rpm and if you feel it will bog the next pas leave the tires the same pressure and ref her a tab higher and see,do remember to chek your tire pressure every run because the air tends to get hot and it will raise your tire pressure.

I've launched at 5500 on these tires on the one and only time I managed to make it to the track. No spin, no bogging, just went. Could probably have went harder, but had the tires at 32psi, simply because I drove it to Vegas, and didn't have any means of re-inflating my tires at the track for the trip back to the hotel.

I plan on taking a video camera, we'll see what I can get out of her.

Oh, and to answer the question about the clutch, it's a 6 puck from Driftmotion, with 2800lb pressure plate. She grabs quite nicely, and I don't make enough torque to get it to slip once I'm off the pedal, so no worries there.

 

[te72]

Tires are on and ready, boost controller is here (had it overnighted from [strike]Japan[/strike] Flyin' Miata when we couldn't find one like we thought we would...

...and then my boss gave me the news. His car won't fit on his 16' trailer, as it's too long. Front bumper hits the front rail, and the rear tires are BARELY on the trailer. Nobody is comfortable with this idea, so we're probably going to modify the trailer and try again for the Midnight Drags at RMR (Utah Supras, meet me there! Friday, June 15th...). Works out better for everybody, to get their cars ready for it, fix the minor issues, and all that fun stuff.

 

[NewGen]

As wreckless as this sounds. I've always had really good luck with the rev limiter. I cut a 1.7X 60ft on 225/37/17 drag radials with 402whp (I have the time slip to prove it). I just come out of the clutch like i'm leaving a stop light so it doesn't shock the drive train but you leave in power car leaves perfect. I'm little worried about my drive shaft next time as the carrier bearing is getting pretty warn so I will be trailering this next time

 

[Devin LeBlanc]

I cut a 1.58 60ft with MT ET Streets and 3000RPM launch with 398 WHP on a full weight mk3. I <3 automatic. With 5 speed I am still getting things dialed in but 2 step is at 4500 or so.

 

[Quin]

20PSI max and long second gear burnout. Only way I could ever get my 555s to hook, I've heard the NT05s are much the same.

 

[xzeror]

I cut a 1.58 60ft with MT ET Streets and 3000RPM launch with 398 WHP on a full weight mk3. I <3 automatic. With 5 speed I am still getting things dialed in but 2 step is at 4500 or so.

Did u run skinnies in the front?

Why do people say not to mix bias ply tires with radials and blah?

 

[Devin LeBlanc]

I ran 225/50/16 Hankook street tires in the front at 65 psi. The Rears were at 14 psi IIRC

 

[Nick M]

I wish I had gone with ET Streets. I was too cheap though. Nitto 555r's beats regular compound street tires hands down though. When I do launch and get wheelspin, the tires recover quickly, grab, and go. I'm sure ET Streets don't put up with wheelspin.

Just a heads up. MT now has an ET Street that is a radial, and not bias ply.

 

[te72]

Thanks for all the input guys, I appreciate it. Got to play with the boost controller a bit, it's hitting fuel cut, even on the lowest setting. I'm thinking that longer lines to/from the boost controller should allow the wastegate time to open before fuel cut. Thoughts?

 

[Nick M]

Did u run skinnies in the front?

Why do people say not to mix bias ply tires with radials and blah?

People don't say it, engineers do. Do you run with a flip flop and a boot? Or do you run in a running shoe? The reason you don't do it is because it is dangerous. Bias ply tires do not flex like a radial ply, and handle very differently (poorly) compared to a radial. When you do mix, you put the radial on the rear. Including (especially) FWD. Oversteer is hard to correct for the everyday non professional driver.