do big stalls kill your top end
TECH Enthusiast
Joined: Mar 2004
Posts: 647
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From: Australia
All smaller converters are designed to slip more than stock, so you will be revving harder for the same axle RPM. A smaller converter will hit harder than stock off the line and give you shift extension that keeps you in your torque band. So your ETs will be lower. As for MPH, it really depends on the trap RPM and efficiency of the converter. However, on the Dyno, a high stall will soak up some rwhp over the stock converter due to slip, reading less peak power.
Some converters are more efficient than others. The higher the stall the more inefficient it is at peak power. But what you lose from the top top you give to the bottom by way of torque multiplication - getting you out of the hole real quick.
The 21 blade stator on its own is irrelevant to determining how efficient a converter is. The combination of the impellor, turbine and stator and engine torque will yield a specific efficiency at high RPM. You can mix and match stators and impellors (pumps) to yield the same stall RPM, but they will deliver different efficiences and torque multiplication.
As said above, it depends what you want to do. What do you want out of a converter? Theres so much info here try doing a search on "converter efficiency".
Some converters are more efficient than others. The higher the stall the more inefficient it is at peak power. But what you lose from the top top you give to the bottom by way of torque multiplication - getting you out of the hole real quick.
The 21 blade stator on its own is irrelevant to determining how efficient a converter is. The combination of the impellor, turbine and stator and engine torque will yield a specific efficiency at high RPM. You can mix and match stators and impellors (pumps) to yield the same stall RPM, but they will deliver different efficiences and torque multiplication.
As said above, it depends what you want to do. What do you want out of a converter? Theres so much info here try doing a search on "converter efficiency".
Simple answer? Yes. You will ET quicker, get up to speed faster, however once your moving your trap speed will be a bit less, or maybe the same.
Example, My friend had a 2001 Z28, automatic. With boltons, stock stall, 3.73's he went 12.12@115mph
He put a 3600 converter in and went 11.95 but his MPH dropped to 111. He was also slower at racing from a roll.
Example, My friend had a 2001 Z28, automatic. With boltons, stock stall, 3.73's he went 12.12@115mph
He put a 3600 converter in and went 11.95 but his MPH dropped to 111. He was also slower at racing from a roll.
Originally Posted by RaNsOm
Simple answer? Yes. You will ET quicker, get up to speed faster, however once your moving your trap speed will be a bit less, or maybe the same.
Example, My friend had a 2001 Z28, automatic. With boltons, stock stall, 3.73's he went 12.12@115mph
He put a 3600 converter in and went 11.95 but his MPH dropped to 111. He was also slower at racing from a roll.
Example, My friend had a 2001 Z28, automatic. With boltons, stock stall, 3.73's he went 12.12@115mph
He put a 3600 converter in and went 11.95 but his MPH dropped to 111. He was also slower at racing from a roll.
your friends car seems exactly like mine.....i juct installed my 3600 and i too feel like i am slower at a roll and not as strong up top??? no times yet though
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from my experience the bigger stall converter will trap better than a stock converter with the same air quality and engine power level. it will loose "dyno power" but who cares about that.
now on a full top speed run (ricer style) on the highways, you will get eaten up by a stock converter car once the stocker catches up.
we put a yank st4000 converter in a stock TA. the mph went from 106 to 108 consistently but "lost" nearly 20 rwhp on the dyno.
now on a full top speed run (ricer style) on the highways, you will get eaten up by a stock converter car once the stocker catches up.
we put a yank st4000 converter in a stock TA. the mph went from 106 to 108 consistently but "lost" nearly 20 rwhp on the dyno.
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In general higher stall, higher STR and lower efficiency all
run together. Efficiency costs you the MPH. The difference
between a 112 and a 110MPH trap, is a 1% less efficient
converter. There's a lot more span, in the converters I have
logs for, than that. Not to mention differences in how fat
the "good region" of efficiency is (higher stalls are peakier
in efficiency, may not even reach peak before your upshift
point, while a lower stall can hit a 97% flat-top and stay
tight for a while).
Design choices alter the tradeoff but efficiency, and efficiency
curves, are seldom shown and seldom asked about. Yet this
is where you lose top end HP. People are more concerned with
raising the weaker low-end HP (times) than what they lose
up top (trap) because time wins the race.
run together. Efficiency costs you the MPH. The difference
between a 112 and a 110MPH trap, is a 1% less efficient
converter. There's a lot more span, in the converters I have
logs for, than that. Not to mention differences in how fat
the "good region" of efficiency is (higher stalls are peakier
in efficiency, may not even reach peak before your upshift
point, while a lower stall can hit a 97% flat-top and stay
tight for a while).
Design choices alter the tradeoff but efficiency, and efficiency
curves, are seldom shown and seldom asked about. Yet this
is where you lose top end HP. People are more concerned with
raising the weaker low-end HP (times) than what they lose
up top (trap) because time wins the race.
Originally Posted by WILWAXU
Strange. My car dropped .60 and picked up nearly 3 mph in the quarter with the swap to the Yank TP-4400. Guess I picked the right converter 
I'd say the difference is in the LT1 and LS1 power band. A high stall actually takes a LT1 out of its power band some. LS1s really start to shine above 4000.
Originally Posted by fastlt1
Same here. I lost 5 mph and gained .5 seconds.
Converters are freakin weird. Some gain mph, some lose mph, im so glad I dont have to deal with that
Originally Posted by Roarin_8
Same here, I lost ET and gained MPH over the stock converter.
I havent tracked the car yet, but i have noticed that the top end hasen't really been affected dramatically..... for example, i raced a c6 with a hurting motor, (stock ls1 manifold, bad broken springs...yeah, i know....but i didnt know until i got home that night!!
) pulled a two car lead didnt budge from there. THe MPH difference wasnt climbing like before but enough to stay in-front. 
I gained .5 in the 1/8 but my trap speed stayed the same. I believe that torque determines ET and hp determines trap speed. So with my converter multipling the tourqe more efficently my car ran quicker but being that my engine setup (HP) didn't change my trap speed stayed the same. This is what I was told by the man that built my race engine in my old mustang. A man who has been bracket racing since he was about 15.
Originally Posted by obZidian
That might have to do with your gear/stall not being correctly matched. A stall that high would "like" a gear set closer to 3.73 than your current 2.73. I didnt want to go higher in gearing so instead of my original choice, the ss3800....i opted for the ss3600 and stayed with my stock 3.23 gear set.
I havent tracked the car yet, but i have noticed that the top end hasen't really been affected dramatically..... for example, i raced a c6 with a hurting motor, (stock ls1 manifold, bad broken springs...yeah, i know....but i didnt know until i got home that night!! ) pulled a two car lead didnt budge from there. THe MPH difference wasnt climbing like before but enough to stay in-front.
I havent tracked the car yet, but i have noticed that the top end hasen't really been affected dramatically..... for example, i raced a c6 with a hurting motor, (stock ls1 manifold, bad broken springs...yeah, i know....but i didnt know until i got home that night!!
) pulled a two car lead didnt budge from there. THe MPH difference wasnt climbing like before but enough to stay in-front. 
i gained .55 in the 1/8 and lost 3 mph after my converter install. i think it's because i didn't have the car tuned for the converter at the time...tqm and also i bounced rl a couple times 2-3 that pass.