Boost at the line - Page 3

DonWG · #71 (**permalink**) March 15th, 2008, 01:43 PM

Quote:

Originally Posted by YouLikeThat

1.50 with a 15# launch. cargo springs, 1 airbag @22psi, lower control arms, boxed uppers,pinion snubber, front sway bar hooked up, M/T et drags at 12.5psi.

New set up HR bar, Stock springs, 2 air bags @ 3psi, no pinion snubber no front sway bar and and about 75lbs off the very front of the car (fiberglass bumper w/alum supports,alum radiator,remove front sway bar) NO TIME YET.

My Question is, what tire pressure is everyone running?
Thanks, Scott

It really depends on the traction limitation you have with your setup. Run the most pressure you can get away with to lessen rolling resistance and provide better handling on the top end. When traction becomes marginal, lower the pressure to provide more of a contact patch at the launch. Lower pressures will also allow more of a wrinkle effect at the launch. This causes a change in the radius dimension from the center of the wheel to the ground which effectively lowers the overall gear ratio and gives you a little better launch. If the power at launch is high you could get too much wrinkle. With that, just raise the pressure a bit.

Most of the racers I know run between 8 and 10 psi, measured before the run. I run 9.25. I used to run 12, but traction was iffy and the sidewall wrinkle was light.

imjoesnuffy · #72 (**permalink**) March 18th, 2008, 07:52 PM

Got the brake issue worked out on my car. I upgraded to the S-10 rear brakes over the winter, my powermaster went out. Turned out to be the electric motor. Replaced it and bled everything, the right way

Took it for a little spin tonight, can now launch at over 15 psi off the foot brake. Could probably do more, but will save it for the track.

YouLikeThat · #73 (**permalink**) March 18th, 2008, 10:05 PM

Quote:

Originally Posted by DonWG

It really depends on the traction limitation you have with your setup. Run the most pressure you can get away with to lessen rolling resistance and provide better handling on the top end. When traction becomes marginal, lower the pressure to provide more of a contact patch at the launch. Lower pressures will also allow more of a wrinkle effect at the launch. This causes a change in the radius dimension from the center of the wheel to the ground which effectively lowers the overall gear ratio and gives you a little better launch. If the power at launch is high you could get too much wrinkle. With that, just raise the pressure a bit.

Most of the racers I know run between 8 and 10 psi, measured before the run. I run 9.25. I used to run 12, but traction was iffy and the sidewall wrinkle was light.

Good info. Thanks!

87GN.Rickie · #74 (**permalink**) March 18th, 2008, 11:16 PM

Quote:

Originally Posted by imjoesnuffy

Got the brake issue worked out on my car. I upgraded to the S-10 rear brakes over the winter, my powermaster went out. Turned out to be the electric motor. Replaced it and bled everything, the right way

Took it for a little spin tonight, can now launch at over 15 psi off the foot brake. Could probably do more, but will save it for the track.

Glad to hear everything worked out for you man! Feels like a totally different car now huh?

Turbo1dr · #75 (**permalink**) March 22nd, 2008, 12:26 AM

I had 1.45 launching at 12psi of boost with a TE 70 P trim. M/T 28x10.5 slicks at 10psi. This was several years ago with a iron headed 3.8L engine.

NJ Torque · #76 (**permalink**) March 23rd, 2008, 05:16 PM

1.54 leaving off the footbrake at 0 PSI.

bluehair · #77 (**permalink**) April 3rd, 2008, 02:24 PM

i ran last night for first time, stock trans, converter, on 26 x 10.5 et streets, left at about 4-5# and was getting 1.80's....tire pressure at 18lbs.

bad V6 · #78 (**permalink**) April 4th, 2008, 11:21 AM

bluehair, what track you making passes at? Brandenburg? Beech Bend begins Saturday night races tomorrow night. Hopefully things work out to where I can be there.

that guy · #79 (**permalink**) April 4th, 2008, 11:26 AM

bluehair · #80 (**permalink**) April 4th, 2008, 11:36 AM

Quote:

Originally Posted by QUICK 6

bluehair, what track you making passes at? Brandenburg? Beech Bend begins Saturday night races tomorrow night. Hopefully things work out to where I can be there.

ohio valley, but i might try to make BG tuesday night next week....

turbo nasty · #81 (**permalink**) April 29th, 2008, 04:36 PM

Quote:

Originally Posted by jurassic five 7

OH JEEEZ!

My 1989 G20 Conversion van with 200k on a 305 TBI was running 15's

and hade 290 HP

, while cutting 1.8 60 foots with my buddies G-Tech.

I guess my van has 290 hp because the G-Tech says so!

You CAN NOT rely on a G-Tech for performance/60 foots/hp.....

-Adam

My buds 9 sec S10 and my GN using the Gtech it is with a tenth. Not sure on the HP and other parameters though

1chance · #82 (**permalink**) May 25th, 2008, 02:56 AM

Well i have a new combo on my GN, and my 60ft times are not the same. Maybe, with this new turbo, i got to leave at 15psi. Being that i do as much of my work i can, i hate to put that much strain on the car(trans).

hottrawd · #83 (**permalink**) June 30th, 2008, 12:23 PM

I had a 2.30 60' leaving on unkown boost(boost guage sticks from 0-10 psi), on 20 year old gatorback tires lol. Comletely stock except for unknown chip that I have to run 1:2 ratio of 109 octane mixed with pump gas, ran a 14.61 @ 95mph, had a 15 mph head wind to drive into. My first time to ever run at the track. Definitely gotta get some tires that will stick so I can up my launch boost. Then put in my 009's and TT chip, upgrade fuel pump and hotwire, then remove the stock cat, and buy me a boost gauge that works. Then see about gettin some 13's.

imjoesnuffy · #84 (**permalink**) June 30th, 2008, 10:09 PM

Quote:

Originally Posted by hottrawd

I had a 2.30 60' leaving on unkown boost(boost guage sticks from 0-10 psi), on 20 year old gatorback tires lol. Comletely stock except for unknown chip that I have to run 1:2 ratio of 109 octane mixed with pump gas, ran a 14.61 @ 95mph, had a 15 mph head wind to drive into. My first time to ever run at the track. Definitely gotta get some tires that will stick so I can up my launch boost. Then put in my 009's and TT chip, upgrade fuel pump and hotwire, then remove the stock cat, and buy me a boost gauge that works. Then see about gettin some 13's.

Everyone has to start somewhere. Get you some sticky tires and see what happens

.

On a side note, I had a personal best 60 FT of 1.60 at BG during the nationals launching at 15 psi, my best prior to that was a 1.70. Nothing different just a different track.

fnsikser · #85 (**permalink**) July 1st, 2008, 11:42 AM

i got a 1.57 coming out at 0...brakes will not hold boost at line...26"et drags w/h&r bar...than backed it up with a 1.59....

GNRick · #86 (**permalink**) July 9th, 2008, 10:54 PM

Quote:

Originally Posted by fnsikser

i got a 1.57 coming out at 0...brakes will not hold boost at line...26"et drags w/h&r bar...than backed it up with a 1.59....

When I first bought my car, the fuel pump was bad. However, I had a 1.67 60 foot. I was able to hold 5 psi at the line. Since then, I replaced the pump and couldn't hold boost. Car would start to push at 3000 rpm, with 0 boost. I was told I could be rich...contacted Eric for a new chip. He took some fuel out at spool up but I haven't tried it yet. Does anybody else have this problem?

DragulaGN · #87 (**permalink**) July 10th, 2008, 12:06 AM

I had this problem with the last set up. Went with a TH-400 and a t-brake...
Problem solved

GNRick · #88 (**permalink**) July 10th, 2008, 08:36 AM

Are you guys running the extender chip where you can adjust fuel at spool up?

ryan george · #89 (**permalink**) July 10th, 2008, 12:43 PM

I'm running 275-50-15 drag radials. Could not leave the line with more than 2 pounds of boost without the tires spinning. Tires were dropped down to 18 psi. I've got a rear HR sway bar and air bags, both at ~ 5 lbs. Any advice, other than getting slicks, to help launch with more boost without spinning? Thanks!