[chevelle swed]

Hi
Going to the track this sunday and run some TNT and has only driven before on my Hoosier Quick Time DOT Tires so now I would like to have some help with start and tire technology. for I thought running on my street tires BFG T / A's 275/60-15. I have had the best 2,002 60 ft on this track before with Hooiser tires. and then the best start I could get was by braked to about 1500 rpm and then rolled 1 foot or 2 and then gassed soft to get a good grip.
So here are some questions:
1. Tire Pressure?
2. Starting rpm?. Converter flashes to 3800 with hooiser tires
3. burn out or just a little scrub of

Track is temporary airport so no prepations on the asphalt

The car has swaybars front and rear, new springs, gas shock absorbers,
boxed lower control arms, adjustable upper, new poly-bushings front and rear. same set up as when I run with Hooiser tires

here is video from race with hooiser

Grateful for ideas from someone who has experience in this

Steven

 

[Steve R]

Don't run too low of a tire pressure. I would start around 30, then go up or down a few lbs at a time. As for a burn out, I would stop when I see a whisp of smoke, that should be long enough to clean off the tires. Try stalling the converter until you feel the chassis just starting to load, you will feel it in the seat of your pants, then stop. You are right about walking the car off the line, just slide your left foot off the brake pedal and roll into the throttle.

Make sure you line up in the darkest part of the groove, keep an eye out for water that has dripped from any previous cars exhaust at the starting line. Street cars are notorious for doing so, especially on cool days.

Keep notes of your changes. Be willing to try different things, every car will react differently. Bring some ballast, run with a full tank of gas or some bags of sand in the trunk.

Good luck, have fun.

Steve R

 

[540Hotrod]

As mentioned.....Add weight to the rear...loosen front end all you can.Don't run air pressure too low. Come out soft. You can try to kill some power with a slower timing curve etc.

I had a 396 Nova once with 3.08's, 3000 stall and I played with the double pumper tuning until I had it right on the edge of bog as it came out of the hole and it worked perfectly on little street tires. I was wide open pretty quick out of the hole but it was a little "flat" and killed enough power to make it hook. It kept the nose high and topped out through low gear.

I wouldn't flash the converter from idle..I'd be into it and try to kill some stall as I walked it out.

A real slow timing curve can kill it down low and then have it when you need it and are moving.


JIM

 

[-SS454-]

2.00 60ft on the BFG's really isn't bad. I don't think there is a lot to gain.

 

[GRN69CHV]

Can you start out in 2nd gear with that trans? You can try that. First 20 feet will be slower, but it will slow down the wheel speed.

 

[MadmanMark]

I looked back at some slips I had from a couple cars that ran the BFG TA 275 60 15s and it looks like the 60' times are in the high 1.7s/low 1.8s (cars were mid-high 12s). I remember practicing timing for how fast I got the pedal all the way down, which could be a lot faster on a prepped track than the street. The worst thing about the TAs is they don't seem to recover well from spinning unless you get off and back on it somewhat carefully. I also don't remember taking any air out and probably ran them at 30-32 psi. Also, a John Force burnout ensured no traction for the launch. A little cleanoff spin seemed all they wanted.

 

[Andy's Auto Repair]

I have literaly hundreds of dragstrip passes on Rad T/As. The biggest thing to remember is they get extremely greasey the more you heat them. Just knock the crap off them and do not try to blow them off and recover. Way better result to feather the gas until you get a feel on how your car is reacting so you can better the next run. Weight transfer is the key. Let whatever your suspension is be all it can be. AKA generally don't load the car. Let the left front lift as you gradually get into the gas. It takes practice. Twenty years ago I was too poor to buy DRs. Usually it was a set of Indys. But in 1998 I ran my best time ever on street tires with an 11.0 @ 126 on spray. Yeah, lots have done way better, but that is the best my old 69 ever ran.

 

[chevelle swed]

Thank you all for plenty of good advice and experience to the test.
We'll see how it goes tomorrow.

Steven

 

[modchevelle]

Get yourself some M/t's or Hoosier quick times. BFG is not a good tire and the tire compound is only good for street driving. not racing. I bought a set of 275 BFG's just to set the car on while I build it and drive it around for its maiden voyage. Then im going to put on some M/T's.

 

[chevelle swed]

I have a set of Hoosier Quick Time DOT Tire but no extra wheels at the moment and it's only 1 day of testing and the ability to run a little slalom as well so I thought to try it.

 

[540Hotrod]

Here's a pic of mine way back when on some BFG T/A's. We literally drove into Bowling Green KY from TX that evening and went straight to the track. Unloaded luggage etc on the ground and pulled to the line without touching it. Pipes hooked up through my old 3" system (that killed it), fat front tires and at the time I had thrown an old Crane 266/276 .600/.620" flat tappet in it I had laying around.

I couldn't get my foot into it until 3rd gear..at all. I made several runs and feathered it the best I could...but I think my 60's were in the 2.4 range! Once I got it moving and into 3rd I stretched it out. It only ran some real low 11 teens or so...but MPH was up in the 131-133 range. I think with some traction and opening the pipes the little weenie cam could have run some high 130's for MPH.

You can see how much the tires are wrinkling up. Fun but slippery ride!!

JIM

 

[chevelle swed]

Well is back from the race track
It was slippery but did manage a 2.122 60 foot 8.309 @ 88.09
which is about 0.3 slower than with Hoosier tires.
Tried everything from 25 to 31 psi and it worked best at 29 psi
Had a nice day and the car was fine all the way home.
Steven

 

[540Hotrod]

Cool...sounds like you did good!

JIM

 

[timvantol]

I ran [email protected] in my chevelle on the Radial T/A's back in January. 1.70 60'

As mentioned not much of a burnout is needed. I would put it in 3rd and floor it for maybe a second at most.

Don't let them spin at all because they don't recover worth a you-know-what. They actually don't work to badly if you can get them to stick through the first 20ft. I was usually able to do a quick roll-into with the throttle and it worked pretty well. Had to back out for a split second when shifting into 2nd.

Mine worked best at 19psi. Any more made it spin very easily, and any less and it would get wheelhop.

 

[chevelle swed]

That is impressive Tim! and thanks Jim, that is a cool and fast corvette you have.
I think I have some exercises to do to reach your times
I did not dare go lower than 24 psi, but maybe I would have continued in that direction and tried a few more times.
I also need to adjust my govenor in the gearbox for it do not want to change to 3 gear until 6800 rpm and the engine pulls best to 6200 so I lose a lot of top speed I think.

Here is the video from today

Steven