Will a Stall effect dyno readings?
Thread Starter
Burning Brakes
Joined: Aug 2008
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From: Tampa (Cigar City) (The Big Sombrero)
Will a Stall effect dyno readings?
I know that if you swap out rear end gears....say to 4:10, that the dyno will read a little lower h.p. than is actually there.
Is the same true with a stall converter? Say a 3600?
Thanks!
Is the same true with a stall converter? Say a 3600?
Thanks!
Race Director
Joined: Mar 2005
Posts: 11,549
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From: Southampton NJ
Race Director
Joined: Sep 2007
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
I doubt the HP readings will effectively be affected by a converter when the RPM exceeds that of the stall speed.
However, you can affect the HP numbers by doing the dyno pull in either 4th or 5th gear (A6 cars) and not properly compensating for the overall gear ratio effect the non-standard 1 to 1 high gear has on the results.
However, you can affect the HP numbers by doing the dyno pull in either 4th or 5th gear (A6 cars) and not properly compensating for the overall gear ratio effect the non-standard 1 to 1 high gear has on the results.
Race Director
Joined: Mar 2005
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From: Southampton NJ
Safety Car
Joined: Nov 2007
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From: Bethesda MD
Aftermarket stalls may be higher or lower efficiency than stock, so you may gain or lose HP at the rear wheels.
Definitely on the old dynojets, the torque ratings for big stalls were all messed up.
Definitely on the old dynojets, the torque ratings for big stalls were all messed up.
Racer
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From: jacksonville fla
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Team Owner
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From: Short Hills, NJ
In my opinion, yes it can but maybe not in every case. Many (most?) aftermarket torque converters are a little lighter (and in some cases, smaller) than stock so not unlike a lighter aluminum flywheel in a manual transmissioned car it could potentially read a little higher than say a stock converter, all else being equal. But contrary to that, for some crazy reason, I have often seen higher stalled automatics actually dyno lower after switching from the stock unit with no other changes.
Thread Starter
Burning Brakes
Joined: Aug 2008
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From: Tampa (Cigar City) (The Big Sombrero)
Alright. So the answer is a definite Yes, No, Maybe So ! 
haha Thanks for the replies.
I'm about to put on ETP heads and the Yank 3600. The yank requires a 150 mile break in period, so I will be doing the heads and stall at different times. I'm just debating on which to do first.
1] The stall...then 150 mile break in...then heads and dyno tune
or
2] The heads and dyno tune for a "true" dyno reading...then the stall (which might skew the readings...but won't be redynoed..so I wont have to worry about the skewed readings)
Thanks again
haha Thanks for the replies.I'm about to put on ETP heads and the Yank 3600. The yank requires a 150 mile break in period, so I will be doing the heads and stall at different times. I'm just debating on which to do first.
1] The stall...then 150 mile break in...then heads and dyno tune
or
2] The heads and dyno tune for a "true" dyno reading...then the stall (which might skew the readings...but won't be redynoed..so I wont have to worry about the skewed readings)
Thanks again
Instructor
Joined: Nov 2009
Posts: 120
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From: Miami FL
I like the way he thinks....lol and Jeremy Formato dyno tuned my car and now I'm going to install a yankss3600. He said that it will show up lower on the dyno but at the track it will show the performance and the man knows his stuff.
Racer
Joined: Apr 2001
Posts: 429
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From: Orlando, FL
Non lockup will mess the readings up. If you have an inertia only dyno than it's just the weight of the roller trying to flash the converter.
I've found that a loaded dyno (mustang or eddy current any other dyno) once you put in the vehicles weight it will flash the converter similar to the track and give you more accurate readings. Same with a turbo car with spooling the turbo. I had a car on my dyno that spooled to 28lbs with inertia only and when I inputed the weight of the car and used the eddy brake it spooled to 35lbs. Big difference in final numbers.
I used to hate dynoing stalled auto's at shows using inertia only. The crying and the bitching was non stop and was one of the reasons I sold the thing.
I've found that a loaded dyno (mustang or eddy current any other dyno) once you put in the vehicles weight it will flash the converter similar to the track and give you more accurate readings. Same with a turbo car with spooling the turbo. I had a car on my dyno that spooled to 28lbs with inertia only and when I inputed the weight of the car and used the eddy brake it spooled to 35lbs. Big difference in final numbers.
I used to hate dynoing stalled auto's at shows using inertia only. The crying and the bitching was non stop and was one of the reasons I sold the thing.
