Stall & MPH
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Melting Slicks
Joined: Mar 2006
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St. Jude Donor '12-'13
Stall & MPH
typically, going from stock stall to 3200 gives (avg.) .4 in quarter mile but what's the effect on mph. also two vettes line up from a roll (same cars) wouldn't the non stall car be faster at higher speed due to the slippage of the 3200???
Le Mans Master
Joined: Aug 2005
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From: CA.
St. Jude Donor '13-'14-'15
I don;t think so--but don't know for sure--I think the TCC would catch up at higher RPM's and the speed would be the same--I have a table on my data-logger that reads TCC slip--I'll have to log some runs and compare it to my buddies car with a 3000 yank---
Race Director
Joined: Mar 2007
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From: Marlton. Increasing performance one speeding ticket at a time! NJ
Le Mans Master
Joined: Aug 2005
Posts: 5,375
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From: CA.
St. Jude Donor '13-'14-'15
Less rotating mass would generate a few more HP of course--but I think the comparison he's asking about is stall vs. non stall and not taking anything else into consideration---for comparisons sake if they both weighed the same--it wouldn't make any differenence--
Dig
Joined: Jan 2006
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From: Port Saint Lucie FLORIDA & HONDURAS
aftermarket convertors can have more " slip " than stock ones in 3rd gear. I've run several convertors over the last few years and found the higher the stall the more the slip ... less mph i get in the quarter.
I am changing my 5000 stall convertor next week and installing a 3800.
I am changing my 5000 stall convertor next week and installing a 3800.
Le Mans Master
Joined: Aug 2005
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From: CA.
St. Jude Donor '13-'14-'15
The lock-up MPH of your converter is a seperate table in the ECM that is programable--It doesn't matter what stall you have in the car the TCC "apply" table dictates when the converter locks up-it doesn't care what converter is installed----As far as having a 5000 stall having less MPH in the 1/4---I've only seen high HP engine applications in the 750-1000 range that use such an outrageously high stall--sounds like a mis-application--even modded cars with super-chargers have about a 3200-4000 stall-------Also when racing the converter remains "unlocked" at WOT -with a stall of 5000 you aren't giving the converter enough time to catch up to the engine speed probably accounting for the lower MPH
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Advanced
Joined: Apr 2007
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From: Conroe Texas
Converters
I am a veteran Automatic Transmission Builder and have built everything high performance that there is. All that the torque converter is made to do in dragracing is to get your engine up to its peak torque output right off the batt. Under cruising applications the lock-up type torque converter normally would lock in OD at 47 mph. Under full throttle conditions though the converter doesn't lock up till u let off the pedal a little. To enlighten you a bit on Torque Multiplication Physics, The IDEAL setup would be a torque converter that would suddenly bring your engine to peak torque rpm off the line and keep it there all the way down the 1/4 mile. Thus, the use of multiple clutches in top fuel/funnycar the person that sets up the clearances in the clutches set this to lock-up more and more while going down the track.
The trick here is to not make lock up too much off the line and not lock up all the way while going down the track.
Thus there is never too much power, (as demonstrated by funny and top fuel) just not nearly enough traction.
Mike
The trick here is to not make lock up too much off the line and not lock up all the way while going down the track.
Thus there is never too much power, (as demonstrated by funny and top fuel) just not nearly enough traction.
Mike
Le Mans Master
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From: CA.
St. Jude Donor '13-'14-'15
Then why are you changing the 5000 to the 3800 ???????
I know what a converter does--perhaps you mis-understood what I was trying to say--You were talking about losing MPH with the 5000 stall vs a lower stall--that was the only issue i addressed to you--don't know why you chose to give me a lesson on converters--perhaps to avoid the issue of your mistake on converter choice--
Just so you know I am a profesional tuner and the TCC lock-up table is commanded by TPS position vs mph--A stock Corvette table from 80% TPS on is set to 255 mph--so it will not allow a lock-up less than 80% tps and it works together with the TCC un-lock table which is set at 100% TPS to unlock the TCC when flooring the throttle so it will not lock at any speed as long as it is at WOT---No need to be a smart ***--just admit you made a mistake with the 5000--There are more issues in choice of stall than just getting into the power band--as you found out going too high loses MPH at the big end---
I know what a converter does--perhaps you mis-understood what I was trying to say--You were talking about losing MPH with the 5000 stall vs a lower stall--that was the only issue i addressed to you--don't know why you chose to give me a lesson on converters--perhaps to avoid the issue of your mistake on converter choice--
Just so you know I am a profesional tuner and the TCC lock-up table is commanded by TPS position vs mph--A stock Corvette table from 80% TPS on is set to 255 mph--so it will not allow a lock-up less than 80% tps and it works together with the TCC un-lock table which is set at 100% TPS to unlock the TCC when flooring the throttle so it will not lock at any speed as long as it is at WOT---No need to be a smart ***--just admit you made a mistake with the 5000--There are more issues in choice of stall than just getting into the power band--as you found out going too high loses MPH at the big end---
Burning Brakes
Joined: Apr 2003
Posts: 908
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From: TROY MI
If you choose the proper TC your trap speed will go up. Most higher stall TCs have better efficency above the stall speed. If you look on the Yank website you can find a plot of this. Their TC has a 97% efficency and thus puts out more HP to the wheels at high RPMs than the stock TC.
The answer to your second question is no for the same reason.
Remember the slipage you are talking about takes place only up to the stall speed.
I gained 2mph in trap speed when I installed my TC.
Safety Car
Joined: Oct 2000
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From: Monticello MN
, so, I don't really know if this is true. When I had my Yank SS3200 installed I had the car redynoed. For whatever reason, the converter wouldn't lock up on the dyno. It operates fine on the street, however. I gave Yank a call and asked them what the rwhp difference would be between a locked and unlocked converter at WOT at peak power. They told me 20-30 rwhp, with the locked number being higher, of course. If anyone has some definitive numbers where they actually tested this, I sure would like to hear about it. 
Ed
