Fire67

iTrader: (3)

How accurate is it? My dyno charts showed HP & TQ over MPH and with the dyno operator shutting down at 6500 the MPH indicated was only 115.

So if this is an accurate measurement, I will run out of gear before the end of the 1/4.

I have a TH400 and 4000stall Vigilante converter, 3.70 rear end gears, and 28X10.5-15 ETdrags. The car put down 550rwhp.

Im looking for suggestions on what to do.

The way I see it is I have 2 options:
1) Change rear-end gear ratio
2) Possibly have converter tightened some

I used a calculator a while back that said I should be good for 135mph... I cannot find the calc now though

I just cant imagine a converter slipping enough to cause such a drastic difference.

Any ideas, input?

WS6TransAm01

iTrader: (13)

This is the calculator that most people use; http://www.f-body.org/gears/

According to it you would have 146mph at 6500 in 3rd gear IF you had a lock up converter/transmission. I don't think there is a way to enter your converter slip into this calculation. But either way I would think that you can get 130mph in the 1/4 easy.

Take it to the track, that is the only way to tell where you are really at.

PS If it makes you feel better on the dyno my car was running out of gear at a little over 125mph on my 275/50 17 M&H's but I trap 131.48 at the track.

Good luck

Fire67

iTrader: (3)

That makes me feel a little better, but not much. I do plan to run it fairly soon, just gotta get my part throttle tune straightened out and an alignment done.

I sure hope the dyno's mph reading is 31mph or so off

kp

iTrader: (34)

The RPM is way high on the dyno (not the mph low) if it was a dynojet and using the older winpep 6 software with a loose converter.

I have 10.5x28s, 3.70 gear and a good converter and 7000rpm is 147mph in reality

Fire67

iTrader: (3)

It was an in-ground dynojet using I believe winpep 7... But it was definitely an older setup. The PC they were using looked like a dinosaur. And the dyno had definitely been in the ground for a while.

KP, if thats the case I definitely feel better. It would suck to drive 45minutes to the track to make one pass and find out that I cant make a full pass.

This car was soooo quick through 3rd gear on the dyno, Everyone there was kinda amazed. The tuner was planning to do a partial pull, but the car revved up so quick it was already at 6500 when he reacted and let out of it.

kp

iTrader: (34)

My 3rd gear dyno pulls last about 1.5 seconds, thats why big stalled autos just dont work for dyno racing.

Depending how efficient your converter is I would guess 134mph @ 6500rpm with what you have.

Navy David SS

iTrader: (13)

http://www.nationaldrivetrain.com/calcs/dragcalc.html

Here's another calculator for the gears. On a NA application, 550 rwhp, you should be able to go much big gears (4.10 or 4.30). I ran my SS with 4.30's NA and on nitrous. Max 615rwhp/650+rwtq on nitrous.

David

Fire67

iTrader: (3)

Well I hope my converter is pretty efficient. Just gotta get an alignment done and we'll get the car on the track for some shakedown passes. Thanks for the input guys.