Gonna hit the 1/8 mile track for the first time tonight, and I just wanted to get some ideas of what you guys are running for tire pressure. I've heard a lot of different PSI's. I'm running the stock Pirelli's up front, and 255/50/17 Kumho Ecstas in the rear.
Pump the fronts up to at least 40. If they're not drag radials/cheat slicks, as stated above, start at 25 and go down from there.
Why do you suggest pumping the fronts up to 40? I ran tonight with just the stock 32 PSI all the way around. My best time was a 9.25 1/8 mile...JLT intake, Bamachips 91 tune, MGW short throw shifter, and the 255's out back. Think next time I'll bring it down to 25, see if it helps. I ran about seven times, and three of those times I spun out when I dropped the clutch.
Increasing the front pressures will slightly "balloon" your tires making the contact patch smaller resulting in less rolling resistance. I ran the OEM 18" BFGs at 33 PSI and managed many 2.0 and a couple of 1.9 60' times. I never experimented with lower pressures.
I'm going back to the track tonight, so I'll definitely try 40 PSI up front, and 25 PSI in the rear. I know I can pull a better time than that 9.25, just a matter of hooking up at launch, and not losing traction going from 1st to 2nd, which I did on every run. Everytime I made that first shift, the back end would start to rumble as my tires tried to gain traction.
Pirelli's and Kumho are not the best for drag racing. Kumho SPT would probably better than the ASX. How are you launching. Are you reving the engine and then dumping the clutch or are you feathering the clutch. If you are reving the engine to 2500 to 3000 RPMs and then dumping the clutch, you will get wheel spin. I am running with street radials as well. I have BFG KDW. I haven't messed with the front tires, but I decrease my PSI in the rear to around 22-25 PSI. My best 60' time is 1.9 and 1/8 mile time is 8.48 (sea level corrected). Upper and lower control arms do help.
I run my Nitto NT555 255/35/20 front tires at 35 psi. I run the rear Nitto NT555R (Drag Radials) 305/35/20s at ~18 psi.
It's actually the track, man...I know a lot of people with my mods are running around 8.7, but this track is poorly cared for. From the water to the tree, it's all rubber. I've seen a lot of street cars race out there, and not one of them is running what they should be with their mods. We have a 1/4 track opening up soon in town, and I'm really looking forward to it, because they've made some big improvements, so I'll really get to see how my car does. Anyway, I only tried one run at 20 PSI before I had to leave, gotta work super early in the morning. Luckily, I did my best time ever, and there's still room for improvement. I either bog my engine down at the start, or launch too high and spin the tires. Still trying to find that perfect launch RPM. Anyway, here are the results of my best time: Reaction - .0070 60 FT - 2.0807 330 FT - 5.8982 1/8 ET - 9.0096 1/8 MPH - 79.03 Plus, I beat a Trans-Am...yay me.
