first time at the track tonight.

[CNshorty93]

made my first run down the track a few hours ago, i ran a 16.53 at 82.13mph, dew was forming on the track so i couldnt hook up so i let off of it then got back in it. when i got back on it i noticed about 3/4 of the way down the track my rpms went down by about 200. i was in non overdrive so i think if i was in overdrive it wouldnt have topped out so soon. opinions? advice on overdrive situation or making it hook better?
video being posted within the hour.

[5.7L JWL]

I'm completely guessing here, but I'm going with the drop is related to your Torque converter lockup. I dont know enough about it to explain it to you but a guy on here that goes by username Pauly can explain it to you.

Go to the thread tittled "My truck is rubbish" by StreetFreak. The last post talks about this.

[CNshorty93]

thanks man, i read it and that seems to be the exact problem i had.

heres the video of my first pass
http://i191.photobucket.com/albums/z221/cnfootball64/th_firstrun.jpg (http://s191.photobucket.com/albums/z221/cnfootball64/?action=view&current=firstrun.flv)

[Fast305]

thanks man, i read it and that seems to be the exact problem i had.



Watch the video of this Chevy Express, its not mine or me, but listen closely as it crosses 80 mph. Thats the TCC locking at WOT in 3rd gear.

http://www.youtube.com/watch?v=qd7OAIATSBQ

FWIW, here is a NBS 1500 with a L31/4L60E and it does the same thing.

http://www.youtube.com/watch?v=aPSrtIFlVpc

[CNshorty93]

so how do i fix it?

[Fast305]

so how do i fix it?

Reprogram the prom to eliminate the WOT TCC Lockup routines.

[custm2500]

Why wouldn't you want the lockup sooner? If the TC is not locked up that means you are not putting all the power down correct?

[Quicksilverado]

Why wouldn't you want the lockup sooner? If the TC is not locked up that means you are not putting all the power down correct?
If it locks the rpms will drop. If you can keep the rpms higher the engine will be in the range where it makes more power. More power equals better acceleration. Thats why people install higher stall tq converters. They will get the engine into its power band quicker.

[dalejrfan88]

You can touch the brake pedal without really applying the brakes. That will cause the converter to unlock.

[custm2500]

I understand you want higher rpms. But why wouldn't a locked up converter be better? No sense in the motor spinning 200 extra rpms if it is because the converter is slipping! Might as well spin your tires down the track.

[Fast305]

I understand you want higher rpms. But why wouldn't a locked up converter be better? No sense in the motor spinning 200 extra rpms if it is because the converter is slipping! Might as well spin your tires down the track.

Thats not the case, you are forgetting what the torque converter is doing, its not all slippage. Its still multiplying torque. Look at these dyno sheets. The only difference is TCC locked vs. TCC unlocked. The average torque is higher under the curve with the TCC Unlocked. Guess which way it accelerates quicker, UNLOCKED. I have the force lock set to lock the converter around 5,000 rpm in 3rd gear, which is over 120 mph.

Locked
http://i243.photobucket.com/albums/ff172/Fast355_album/TPI/305Dyno2.jpg

Unlocked
http://i243.photobucket.com/albums/ff172/Fast355_album/TPI/305Dyno1.jpg

[CNshorty93]

interesting, so i can send my prom out and get it reprogrammed to where it wont do that?
ive been meaning to do that anyway, so now im definately gonna look into it now

[custm2500]

Cool I thought about the torque multiplying wile at work today. I have defiantly learned something today. Do most auto trannies work this way?

[CNshorty93]

also, what do yall recommend for gears? i want to go 3.55, 3.73, or 3.90 . . . maybe even 4.10. i drive in 30-50 miles of city traffic daily and i would like to keep somewhat good gas milage

[96ImpSS]

Primarily city traffic, then steep gears won't hurt your mpg at all. Go 3.73 or steeper. 3.55's in my opinion would be a waste of time and money.
What dia are your rear tires? If 29" or less, 3.73's would do you well. 30" or more, I'd go with 4.10's.

[5.7L JWL]

96ImpSS, as many times as I've seen your '96SS sig, I just noticed the 11.33 @ 116.6. Thats basically the same (best)number we've run in the "Toyvrolet" 11.29 @ 116.

I'm going to go out on a limb and say you outweigh us by a few pounds:aniteef: Those are good numbers for a car that size!

[CNshorty93]

my rears are 28.5 inch tall and 11 inch wide, i was thinking 3.73 would be good, a big improvement from 3.08