Question: What would the ideal gear ratio be for my Top Dragster?

Currently my car stats are: 280" RED, 526 KB hemi with AJ Muscle heads, DMPE - M4 (32lb boost in Denver)(40lb boost in Topeka), 3 speed Bruno/Lenco (1.73 Low Gear, 1.25 x 1.38), 4.10 rear end, 34.5 Goodyear tires(pressure-7.5lbs), Coan Converter(6000 stall)

Starting Line RPM - 5500/5600

Current problem is that we started having traction problems.

I made 7 runs this week end(Bandimere) and had 6 runs with smoke? The first run was good(6.61)with my standard Bandimere tune up.
Made the following changes with no success:7.75 tire pressure, 8.0 tire pressure, back to 7.5 tire pressure, 5 degree retard in the six shooter.
Tires have over 40 runs on them!
Just put on New tires! (No Runs yet!)

Current Ratio: 1.73 x 4.10 = 7.093 My thoughts are that the ratio is to low!

Any thoughts about a more ideal ratio?

Oenes Motorsports
Leon

 

ratio

Does it shake at all and then smoke, or just completely blow the tire off?
I don't know about dragsters but those ratios would work ok in a door car.
If you want consistency more than all out ET a taller ratio would probably be good.

The way it was explained to me is set the rear gear to redline accross the finish.
Pull as tall as you can in low gear with about 7 degrees of timing out on the hit. That gives you a tuning window for different tracks.

Seems that everything clutch or auto is pulling a lot taller low gears than they used to?
Maybe it's just the blower hp improvements.

 

Ratio Question

It shakes and then it smokes! Seems like it happens at the same time!! My driver can't feel the shake, he can tell if it spins/smokes because it stops accelerating. What seems strange is that every thing was fine until the last six runs. That's why I put new tires on. The side walls on the old tires looked well used.

Question: Do you swap tires side to side? If you do how often?

My thought is to go to a smaller ratio to load the motor more!!

If I run it as a 2 speed the ratio would be: 1.38 x 4.1 = 5.568

Thanks for you input.

 

Gear ratio

Sounds like you need to drop tire pressure and it will help it hook.

 

Shake at the hit.. not enough power... tire smoke at the hit too much power. But I think your problem is too much air pressure. With 7.5 lbs the tire hooks too good and the entire footprint of the tire is on the asphalt. Go to 6.00 to 6.25lbs and the tire will cup up in the middle and let you get some wheel speed. With wheel speed correct the shake will go away at the hit, also try leaving at appox. 4000rpms, 5000 to 5500 is too much. At this tire pressure you will be close, now if it spins at
the hit take more timing out while on the two step and ramp it back in by 1.8 sec. Also you may want to try MT 3187 34.5 tires if you are running beadlocks, they have always worked well for me...not saying the Goodyears won't but i have alot of runs on MT's. Call me if you need to speak with me 843-921-8653.

 

Jody I think you hit it on the head...Dave

 

Maybe it's just as simple as, the tires are dead......done.....used up.....??

If you've just installed new tires, that will tell you in a hurry.

Ron Clevenger
Creekside Racing Ministry........John 14:6