is there a program that can help me with figuing out what needs work ? my car ran a 15 sec quarter with a 100 MPH trap speed do i need steeper gears i have some tire spin for about 20 feet with street radial and i need a stahl converter buy my rear is a 3.08 because i will be going to a 200r 4 so i will have a 3.73 gearingin the rear with the trans and lots of top end.

Here's the program:
Get deeper gears, 3.73 w/posi would be ideal with a 200r4. And get a decent 2500 (11") stall converter.


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73RS/LT/427

Get some stickier tires too ;-)

Ditto what ZS10 and slmmr75 said

There's a bunch of programs.. Performance trends DA, DD2000 drag, etc etc, but they all go by gen rules of thumb and not always the case with every car.

Ask people that knows, do alot of research on stuff you want to find out.

I'll start by telling you, your short times has to be bad. You need more power out of the hole, and you need less wheel spin.

MPH tells power
ET tells traction, and power

15 sec @ 100 mph, shows you have the mid range and top end power to over come bad starts.

100 mph should be 13.40's with a good launch, good traction, etc

common trap speed of a 15.00 sec car is only 89-90 mph with good traction

You need deeper gears (3.42-3.73's), better tires that grips better, cant say on stall speed w/o knowing cam, compression, etc etc, but norm. most hot street cars will binifit from a converter in the 2200-2600 rpm range.

And you need to work on your launches more. Are you just stabbing the throttle? If so try rolling into it. What about launch RPM? Play with diff rpm's to find where you can launch with out getting alot of wheel spin

thanks thats what i was thinking i am makeing good power the fact that i have that much wheel spin with 3:08 posi tells me that I was wondering about 100 MPH in the quarter with 15 i figured it was my gearing. I have a comp cam 280 H magnum with 71 LT1 heads about 10.1 cp,

Firt thing I would do is get some traction. A set of DRs will make a HUGE difference over street rubber in the launch. 3.08s aren't optimal for sure, but you'll never know how fast you can go until you get some "stick" out back.

Not knowing your whole combination, but having built similar stuff I can tell you that with nothing but traction and some tuning I'd be surprised if that combo couldn't run a 14.0 even with the current gears.

Deeper gears are going to make your traction problems worse, but once you get the car hooking up all should get better. Work on the suspension and tires are going to be MANDATORY with or without a gear change. Your making good power, just need to get it to the track.
Depending on how serious you are about ET, weight reduction on the nose of the car (fiberglass hood, moving the battery tothe truck, removing inner fender panels etc), making sure the front suspension is free, and not binding, remove the sway bar, drag shocks, smaller lighter front tires, springs that allow a lot of upward rotation of the front end (drag springs or use 6cylinder springs) remove the AC/ heater box,,,, all sorts of things you can remove / relocate to get weight off the nose. The goal is to allow the front of the car to pitch rotate at the stab of the throttle. As the nose goes up, it transferes weight to the rear helping plant them. Once you get that accomplished, you can start on the rear. Traction bars / CalTracks / Lift bars, springs that allow enough movement, but not too much movement, SHOCKS!! If you have air shocks your shooting yourself in the foot for traction. You need GOOd shocks, adjustables would be ideal. With all the tweeks and tricks you can throw at the car, the single most important tool you can have is the video camera. Launch the car on a good track and get video of what is happening. Review it frame by frame and see exactly where and why it's loosing traction. The car should 'pitch rotate'. As the nose rises it should transfer weight onto the rear and drive the tires to the track. Some cars will actually suck the rears up into the chassis unloading the tires, that's worse than getting no weight transfer at all. The nose should rise, causing the rear to squat just a little as weight hits the springs, BUT the tires should be driven down towards the track at the same time so you should see very little change in the attitude of the rear of the car.
Making all of this happen can be illusive. Only way to see what is happening is video and test, and test, and test, and test. Change ONE THING AT A TIME and see what the results are. You may find a 500rpm change in launch rpm can make big differences in how the car reacts.

I used to be in that same boat. I ran 101 mph and 15 seconds with a 2.56 gear behind a TH350. It never got out of 2nd gear at the trap. I swaped it out for a 3.42 out of a T/A and the speed stayed exactly the same. Times fell to 14.2's. The stall converter knocked it to 13.8 with mild spinning. A set if ET Streets, and it came down to 13.38. So there you have it.

I had a very similar combo in my 81 in college. I did get it to run 14.20s at about 98 after figuring out how too dog it out of the hole. I also did some of the dodge superstock leaf spring tricks. Made a difference even with the 225 70s I was running. Gears are a huge help and would have made my car a lot quick in the 60 FTs but like you I didn't have the tire to keep up with the better gear. One thing to remember is that with a high gear once the tire starts to spin it will be harder to get it to stop spinning. A lower gear will have less of a tendency to spin forever and still help your ET. Thats why a burnout contest is best with a high gear. Once you get the tire to spin with high gears it will tend to keep spinning. The problem with a good tire and the 3.08s is with out a deep gear your car will really dog coming out of the hole. Now you are rasing your RPMs with the tire spin.

I will be putting in a 200R4 so my effective rear ratio will be 3:73 and in over drive it will be like 2:41 so i get the best of both worlds.

Hey JB.. One of us is mixed up with the math of gearing.

I may be wrong, but I thought to find final gear ratio it's trans gear x rear gear

well 2.52 x 3.08 = 7.7616
2.52 x 3.73 = 9.3996

and for the 2004R 2.74 x 3.08 = 8.4392

If my math is righ then going to a 2004R would not be the same as a th-350 with 3.73

It would be more like a th-350 with a 3.35 rear gear (2.52 x 3.35 = 8.442)

my rear is 3:08 but with a 200R4 my effective rear ratio will be 3:73