Drag Radial Tire Pressure

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furrystump said:
So the car is a high 14 second car. Runs 2.19 60’ spinning? Is this a new combo or just a tire change? You can get in the ball park by looking at the tire marks after spinning the tires. You want an even color all the way across. Light in the middle add 2 lbs. light on the edges take out 2 lbs. when it is even you are close enough to play with it at the track. I assume it’s an auto, try loading the converter. I know its counterintuitive, but I have found that leaving at idle allows my converter to flash to high and knocks the tire off. By loading it it goes up to stall speed not really up to the flash rpm until I’m farther down track.
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The combo (car) is new to me. This was the first time at the track. Good advice on the tire marks. I can not "load the converter much" without rolling through the beams but I will try.

Time slip attached four everyones perusal. The Dart was in the right lane. At least I hooked better than the car next to me. :)

I will try 20, 18 and 16lbs. Look forward to a report after Saturday.

Thank you again to everyone.
IMG_20190416_085600207.jpg
 
GreyWizard said:
The combo (car) is new to me. This was the first time at the track. Good advice on the tire marks. I can not "load the converter much" without rolling through the beams but I will try.

Time slip attached four everyones perusal. The Dart was in the right lane. At least I hooked better than the car next to me. :)

I will try 20, 18 and 16lbs. Look forward to a report after Saturday.

Thank you again to everyone.View attachment 1715320854
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Actually, that 60 ft time is on que for the rest of the ET.
 
318willrun said:
Actually, that 60 ft time is on que for the rest of the ET.
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but spinning the tire. The combo is new to him so I think the car is quicker than high 14’s. That’s a good size tire to spin on a prepped track. I have very good front brakes, but I still have to stand on the brakes to not roll the beams. There might be other “issues” keeping the mph down.
 
GreyWizard said:
How 'bout 318 heads on a 360?
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And the altitude is obvious. If you ran that at my track you could take a for sure full second off that ET (and maybe a couple tenths more) and add some mph.
 
I typically run around 19 psi with 1.4x 60’ on my radials. But that’s not always the case at every track, or every lane even! Last week I ran 1.4’s in the left lane and 1.7’s in the right lane at this particular track and I couldn’t figure out what prep they did to make the lanes so different. Could
Be dealing with track prep issues.

Also have you tried rolling into the throttle instead of nailing it right off the line?
 
AJ/FormS said:
I can't get my 325/50-15s to hook no matter what I try,lol. The 60fts are over 2.2 and into the 2.4s,lol. I wasn't there for ET that day,just MPH.
BFG-DRs
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Sounds like a possible suspension issue. That and I think it's been a good while since BFG Dr's were made. lol
 
The guy in the Left lane is running worse than you...
106 mph and 14 secs with a 2.5 60 ft !
 
318willrun said:
And the altitude is obvious. If you ran that at my track you could take a for sure full second off that ET (and maybe a couple tenths more) and add some mph.
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For certain. The density altitude Sunday was over 8700'.
 
Your MPH matches up pretty well with ET and 60'. I would try 18lbs and do a short-ish 2nd gear burnout in the water box. You may see a small improvement, but the MPH says it won't be much.

One of my old 360 combo's used to run 14.0-13.5 naturally aspirated at Bandimere....and 11.1 on the bottle :-D

The air is so thin up there in the summer time that I found it best to bring my own atmosphere (in a bottle). Super consistent, and a lot of fun.
 
Walker434 said:
I run 275/60/15 MT ET SS drag radials. I can get away with running 20 PSI at a well prepped track. If the track isn't good I drop down little by little. I wouldn't run less than 16 psi on a drag radial.
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A 28-inch-tall Pro Drag Radial on a 3,200-lb car should run a minimum of 12 psi; the same tire on a 2,800-pound car can go as low as 10 psi

Mickey Thompson suggests the tires be heated to within 15 degrees of the track temperature.
Drag radials need less burnout because the special compounds that make them streetable gets gummy when they are heated too much. ET Street and Street Radial tires only need a short spin to haze the tires as they heat up quickly. This brings the special compounds to the surface, increasing the stickiness of the tire. BFGoodrich suggests a light spin to clean up the rubber and put a little haze on it as well. If you put too much heat in them they start to ball up, kind of like when you rub an adhesive and get little balls of goo. That balling up can actually work against you, slowing down the car in the first 60 feet. In the end, you need to take the manufacturer’s suggestions and experiment with your car.
 
flyfish said:
Your MPH matches up pretty well with ET and 60'. I would try 18lbs and do a short-ish 2nd gear burnout in the water box. You may see a small improvement, but the MPH says it won't be much.
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My carburetor is too big and my heads are too small. The plugs indicate a lean condition. I will go up one size on the primaries, set the pressure at 18 and hold on. :)
 
I run my 275/60-15 M/T drag radials around 12psi 99% of the time, street use. If I want to spin some and get up on them for expected show/cruise fun, I air them up to 30. I like the car to stick and launch hard for my normal jaunts!
 
If the carb is to big it will run lean. The motor can’t move enough air to create enough velocity through the booster to pull fuel.
 
furrystump said:
If the carb is to big it will run lean. The motor can’t move enough air to create enough velocity through the booster to pull fuel.
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That is good information. Changing the primary jets had little if any effect. Now I know why.

Thank you.
 
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