PI converter stall - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 32 (permalink) Old 06-22-2009, 03:18 PM Thread Starter
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PI converter stall

Those of you running a PI converter, what is your stall set at?

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post #2 of 32 (permalink) Old 06-22-2009, 03:45 PM
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Re: PI converter stall

I installed one in a truck awhile back.. I was told it was around 2000rpms.

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post #3 of 32 (permalink) Old 06-22-2009, 06:13 PM Thread Starter
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Re: PI converter stall

Whats the easiest way to check it?

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post #4 of 32 (permalink) Old 06-22-2009, 06:46 PM
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Re: PI converter stall

Torque converter stall is a commonly used term and is commonly misunderstood. Stall is the speed at which the converter will hold the engine speed and not allow further gain (i.e., the engine "stalls"). The key word here is engine. The speed at which stall occurs with a given converter is a function of engine peak torque. It is clear that the stall speed on a given converter will not be the same coupled to a tame small block engine when compared to a big block with all of the muscle features added. When comparing stall speeds it is important to account for the engine that drives it. True converter stall can best be determined when a Transbrake is used. Testing for stall value by locking the wheel brakes generally does not produce a true stall value because the engine power can often cause wheel turn by overpowering the brakes. Stall speed determined by this method should be identified as such when discussing stall speed determination. Flash stall is determined by launching at full throttle and observing the peak speed attained at launch. Selection of the right stall speed for your vehicle should be matched to the engine peak torque, engine torque curve shape and vehicle weight. In general, the stall speed selected for your converter would be 500 to 700 rpm below the peak torque. This speed allows the margin for application of the torque reserve on takeoff. When selecting stall speed without having prior experience to go by, it is better to conservatively estimate the engine torque than it is to over estimate it. If you over estimate the torque output you will have a converter with a stall speed too low, making your car slow off the line and have slow ET. A properly selected stall speed will give you better launch and better ET. You can see why it is important to consult with professionals prior to making a stall speed selection. Within the converter, stall speed is balanced off against inefficiency after launch. Getting desired stall at the expense of performance after launch is just as costly as improper stall speed to begin. The optimum converter has careful selection and design of changes to the impeller, turbine and stator.

From: Precision Industries - FAQ's


One thing I noticed is that the TC that BTS installed is either lower stall than stock (not likely), or much more efficient. It feels like the stall is lower simply because it pulls more at idle than the stock one did.

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post #5 of 32 (permalink) Old 06-22-2009, 11:42 PM
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Re: PI converter stall

Might be a little backwards there. I don't know really, but this is my guess.

Lower stall on a Powerstroke will be more doggy, or slower just casually putting off idle around town, traffic lights, stop signs. Higher stall will let the RPMs raise, more power, more boost, more whatever and the truck will start to move a little later than the lower stall making it not as a "dog" since you're already up in some RPMs.

You obviously wouldn't want a 1,200RPM stall on a 600RWHP 7.3L.
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post #6 of 32 (permalink) Old 06-23-2009, 12:08 AM
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Re: PI converter stall

Quote:
Originally Posted by cowboy_dan View Post
Torque converter stall is a commonly used term and is commonly misunderstood. Stall is the speed at which the converter will hold the engine speed and not allow further gain (i.e., the engine "stalls"). The key word here is engine. The speed at which stall occurs with a given converter is a function of engine peak torque. It is clear that the stall speed on a given converter will not be the same coupled to a tame small block engine when compared to a big block with all of the muscle features added. When comparing stall speeds it is important to account for the engine that drives it. True converter stall can best be determined when a Transbrake is used. Testing for stall value by locking the wheel brakes generally does not produce a true stall value because the engine power can often cause wheel turn by overpowering the brakes. Stall speed determined by this method should be identified as such when discussing stall speed determination. Flash stall is determined by launching at full throttle and observing the peak speed attained at launch. Selection of the right stall speed for your vehicle should be matched to the engine peak torque, engine torque curve shape and vehicle weight. In general, the stall speed selected for your converter would be 500 to 700 rpm below the peak torque. This speed allows the margin for application of the torque reserve on takeoff. When selecting stall speed without having prior experience to go by, it is better to conservatively estimate the engine torque than it is to over estimate it. If you over estimate the torque output you will have a converter with a stall speed too low, making your car slow off the line and have slow ET. A properly selected stall speed will give you better launch and better ET. You can see why it is important to consult with professionals prior to making a stall speed selection. Within the converter, stall speed is balanced off against inefficiency after launch. Getting desired stall at the expense of performance after launch is just as costly as improper stall speed to begin. The optimum converter has careful selection and design of changes to the impeller, turbine and stator.

From: Precision Industries - FAQ's


One thing I noticed is that the TC that BTS installed is either lower stall than stock (not likely), or much more efficient. It feels like the stall is lower simply because it pulls more at idle than the stock one did.
I thought BTS used PI converters ???? My PI was alot more efficient than the stocker!

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post #7 of 32 (permalink) Old 06-23-2009, 12:40 AM Thread Starter
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Re: PI converter stall

Whats the stall on your truck?

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post #8 of 32 (permalink) Old 06-23-2009, 12:48 AM
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Re: PI converter stall

Been so long since I have driven it ........ Ask me in 2 more weeks I am going to get it . I wanna say 1800 rpms !

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post #9 of 32 (permalink) Old 06-23-2009, 12:49 AM
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Re: PI converter stall

Are you getting a better trans cooler than the stock OBS ?

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post #10 of 32 (permalink) Old 06-23-2009, 12:51 AM Thread Starter
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Re: PI converter stall

Me? Yes i have a 6.0 cooler. I rebuilt my own trans and installed a pi converter and stall seems to be around 1000rpms, thats all i can get out of it. Trans works flawless. Just trying to narrow a few things down.

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