Torque Converters and the Dyno
Melting Slicks
Joined: Jun 2001
Posts: 2,743
Likes: 3
From: Davie Florida
A numerically higher gear like 3.73s will give you a lower dyno reading than a lower numerical gear like a 3.15 gear. All things being equal except for stall speed a higher stall T/C will dyno lower than a converter with less stall in most cases.
Team Owner
Joined: Aug 2003
Posts: 38,314
Likes: 35
There was a discussion about this over on LS1 tech a while back. The experiences of those who had dynos done with higher stall converters were slightly lower dyno numbers than they had with their stock converters. Yet another reason why dyno numbers should be taken for what they are worth.
Le Mans Master
Joined: Aug 2000
Posts: 5,294
Likes: 2
From: Suffolk, Long Island NY
Originally Posted by EB20003
There was a discussion about this over on LS1 tech a while back. The experiences of those who had dynos done with higher stall converters were slightly lower dyno numbers than they had with their stock converters. Yet another reason why dyno numbers should be taken for what they are worth.
That explains my 11.1 @ 121 timeslip with only 388rwhp.
Burning Brakes
Joined: Jul 2002
Posts: 791
Likes: 52
Generally the higher the stall rpm, the more loss of horsepower due to slippage. However it really depends on the efficiency of the converter itself. This is why you see "unlocked" and "locked" dyno's for an A4 car.
Most A4 dyno runs are with the converter unlocked in 3rd gear. When you lock the converter on a dyno you will see more hp to reduce slippage (once again depends on the actual converter) and less torque compared to an unlocked run, which see less hp and more torque (usually a torque spike when you flash or hit the converter to start the dyno run).
My car with a TCI 3800 stall saw a difference of 18rwhp between locked and unlocked. Not as efficient as the stock converter, but the trade off for a lower ET is well worth the slight hp loss.
Most A4 dyno runs are with the converter unlocked in 3rd gear. When you lock the converter on a dyno you will see more hp to reduce slippage (once again depends on the actual converter) and less torque compared to an unlocked run, which see less hp and more torque (usually a torque spike when you flash or hit the converter to start the dyno run).
My car with a TCI 3800 stall saw a difference of 18rwhp between locked and unlocked. Not as efficient as the stock converter, but the trade off for a lower ET is well worth the slight hp loss.
