Stall speed question
#2931272
06/08/21 01:30 PM
06/08/21 01:30 PM
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Joined: Jun 2018
Posts: 114 Oklahoma City, Oklahoma
MrMayhem
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Posts: 114
Oklahoma City, Oklahoma
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The other day my mind was wandering as I was shopping for a new converter and I came across a question in my mind that I feel needs a solid answer. To the best of my knowledge, the purpose of the stall is to allow the engine to rev more freely until it is in it's optimal power range for the purpose of the motor. In the case of a stout 440 where it will make a significant amount of torque say 500lb ft from the 2500 rpm range and up, what is the benefit of having a 3500 plus stall in the same motor? If a big cammed 440 is making over 500lb ft of power around 2500 rpm but increases it's torque through say 5000 rpm and max rpm is 6500. Said engine with a stall speed that is at 3800 rpm per the cam grinder recommendation. In this scenario, are you not wasting the torque the engine is producing below that 3800 rpm point? I guess in short, why use a high stall converter if your engine produces usable power at a lower RPM range?
Last edited by MrMayhem; 06/08/21 01:55 PM.
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Re: Stall speed question
[Re: MrMayhem]
#2931291
06/08/21 02:07 PM
06/08/21 02:07 PM
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Joined: May 2019
Posts: 165 W. Pa
usp4u
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Is it being wasted? Sure, but the associated lack of engine speed would mechanically negate anything you are trying to gain. It is the torque value + engine speed that is going to accelerate the car.
We all know torque over time is what gets work done. With higher engine speeds the work is being done in a shorter time, thus, improved acceleration.
Last edited by usp4u; 06/08/21 02:08 PM.
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Re: Stall speed question
[Re: A727Tflite]
#2931307
06/08/21 02:42 PM
06/08/21 02:42 PM
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Joined: May 2019
Posts: 713 Lake Villa Il
INTMD8
super stock
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super stock
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Lake Villa Il
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For max acceleration you want to spend as much time in the rpm range of max average horsepower.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Stall speed question
[Re: MrMayhem]
#2931392
06/08/21 06:21 PM
06/08/21 06:21 PM
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Joined: Jan 2003
Posts: 25,942 Rio Linda, CA
John_Kunkel
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Rio Linda, CA
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Converters are sold by stall speed because that's what most folks think they understand but, like Transman said, it's all about the stall ratio.
The INTERNET, the MISinformation superhighway
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Re: Stall speed question
[Re: A727Tflite]
#2931429
06/08/21 08:06 PM
06/08/21 08:06 PM
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Joined: May 2011
Posts: 4,489 northern,Ohio,USA
Clanton
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Depending on the design of the converter, the other benefit of the higher stall in many cases is higher STR.
Stall Torque Ratio. Here is a link to an explanation. web site
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Re: Stall speed question
[Re: INTMD8]
#2931434
06/08/21 08:15 PM
06/08/21 08:15 PM
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Joined: Jan 2003
Posts: 10,015 Frostbitefalls MN (Rocky&Bullw...
gregsdart
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For max acceleration you want to spend as much time in the rpm range of max average horsepower. That high torque 440 with a 2600 stall converter will only be able to deliver the actual hp being made. 500 ft lbs torque only makes 250 hp at 2600 rpm. At 4000 rpm the 500 ft lbs has climbed to 400 hp. If the motor makes 500 hp at 5200 rpm, and the motor will still make 500 hp at 6200 rpm you have the full 500 hp average, minus efficiency loss, if you have a 5200 stall converter, average power delivered will be highest. Stall torque ratio and overall efficiency can skew the actual best stall speed.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Stall speed question
[Re: MrMayhem]
#2931984
06/10/21 01:38 PM
06/10/21 01:38 PM
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Joined: Jan 2003
Posts: 10,015 Frostbitefalls MN (Rocky&Bullw...
gregsdart
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You and I both know the answer is what your trying to do is what are you trying to do with this converter first Street, street and strip or race only? Yes that is correct but, trying to figure out where money is best spent... Like you mentioned, some parts (stall speeds) will be more specific or efficient to a specific application. It's always a compromise, if I frequently drive my car on city or hwy streets, it probably would not be wise to choose a 4k converter. If the car is driven more street than race/strip maybe I could get away with a 2800 stall... the compromise between the two would be a 3k-3500k converter as that is in my case the cruise rpm My guess is a tight ten inch converter should get you reasonable lockup yet stall 3000 or so.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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