Stall Speed for aftermarket torque converters
11/21/07, 11:32 AM
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Stall Speed for aftermarket torque converters
I had a Fuddle Racing Converer installed in my 07 GT Automatic a few months ago. Really love it and it really improved my short times at the local drag strip. Way cooler on the street, too, as it's always in the sweet spot for torque with just a gentle nudge of the throttle - even without downshifting!
Any stall converter experts around here? I have a question...
I know from previous cars with high rpm stall converters that modifying a car for more power typically bumps up the stall speed beyond its rated stall speed. My understanding is that more power forces to converter to be looser (higher rpm flash/stall). But how much increase in stall speed is normal?
For example, I owned a 1968 Pontiac GTO for many years. Campaigned it in the Sportsman class (1/4 mile drags) for 9 years. Bought an Art Carr converter that flashed to 2,800 rpm's originally. Had the car dyno tuned with timing recurve and carb jetting for more power and the car would then flash to 3,100 rpm's. Only 300 more rpm's, so it was OK.
My 2007 Mustang GT has a factory stall speed of about 2,200 rpm's. The converter I had installed was rated to flash to 3,400 to 3,600 rpm's for an all-stock GT. I had already changed tunes in the car for more power, so it actually was flashing to 3,800 to 4,000 rpm's. Then last week I installed a JLT CAI and tune, and the car feels a tad bit stronger (seat of the pants), but the converter is now flashing to about 4,300 rpm's! The air is really cold now (it's 35-40 degrees outside this week), so the air helps a bit. But, would just adding a CAI generate enough additional power to push the stall speed up that much?
Granted, peak torque in a 4.6L 3V is about where my converter is currently flashing to, so it puts me right in the thick of the powerband, but what happens if I continue modding the car? Will I eventually find it flashing to 5K or 6K rpm's? That would suck and I'd need to change converters to something mellower.
Any advice or thoughts are appreciated.
Any stall converter experts around here? I have a question...
I know from previous cars with high rpm stall converters that modifying a car for more power typically bumps up the stall speed beyond its rated stall speed. My understanding is that more power forces to converter to be looser (higher rpm flash/stall). But how much increase in stall speed is normal?
For example, I owned a 1968 Pontiac GTO for many years. Campaigned it in the Sportsman class (1/4 mile drags) for 9 years. Bought an Art Carr converter that flashed to 2,800 rpm's originally. Had the car dyno tuned with timing recurve and carb jetting for more power and the car would then flash to 3,100 rpm's. Only 300 more rpm's, so it was OK.
My 2007 Mustang GT has a factory stall speed of about 2,200 rpm's. The converter I had installed was rated to flash to 3,400 to 3,600 rpm's for an all-stock GT. I had already changed tunes in the car for more power, so it actually was flashing to 3,800 to 4,000 rpm's. Then last week I installed a JLT CAI and tune, and the car feels a tad bit stronger (seat of the pants), but the converter is now flashing to about 4,300 rpm's! The air is really cold now (it's 35-40 degrees outside this week), so the air helps a bit. But, would just adding a CAI generate enough additional power to push the stall speed up that much?
Granted, peak torque in a 4.6L 3V is about where my converter is currently flashing to, so it puts me right in the thick of the powerband, but what happens if I continue modding the car? Will I eventually find it flashing to 5K or 6K rpm's? That would suck and I'd need to change converters to something mellower.
Any advice or thoughts are appreciated.
11/22/07, 08:26 PM
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I had a Fuddle Racing Converer installed in my 07 GT Automatic a few months ago. Really love it and it really improved my short times at the local drag strip. Way cooler on the street, too, as it's always in the sweet spot for torque with just a gentle nudge of the throttle - even without downshifting!
Any stall converter experts around here? I have a question...
I know from previous cars with high rpm stall converters that modifying a car for more power typically bumps up the stall speed beyond its rated stall speed. My understanding is that more power forces to converter to be looser (higher rpm flash/stall). But how much increase in stall speed is normal?
For example, I owned a 1968 Pontiac GTO for many years. Campaigned it in the Sportsman class (1/4 mile drags) for 9 years. Bought an Art Carr converter that flashed to 2,800 rpm's originally. Had the car dyno tuned with timing recurve and carb jetting for more power and the car would then flash to 3,100 rpm's. Only 300 more rpm's, so it was OK.
My 2007 Mustang GT has a factory stall speed of about 2,200 rpm's. The converter I had installed was rated to flash to 3,400 to 3,600 rpm's for an all-stock GT. I had already changed tunes in the car for more power, so it actually was flashing to 3,800 to 4,000 rpm's. Then last week I installed a JLT CAI and tune, and the car feels a tad bit stronger (seat of the pants), but the converter is now flashing to about 4,300 rpm's! The air is really cold now (it's 35-40 degrees outside this week), so the air helps a bit. But, would just adding a CAI generate enough additional power to push the stall speed up that much?
Granted, peak torque in a 4.6L 3V is about where my converter is currently flashing to, so it puts me right in the thick of the powerband, but what happens if I continue modding the car? Will I eventually find it flashing to 5K or 6K rpm's? That would suck and I'd need to change converters to something mellower.
Any advice or thoughts are appreciated.
Any stall converter experts around here? I have a question...
I know from previous cars with high rpm stall converters that modifying a car for more power typically bumps up the stall speed beyond its rated stall speed. My understanding is that more power forces to converter to be looser (higher rpm flash/stall). But how much increase in stall speed is normal?
For example, I owned a 1968 Pontiac GTO for many years. Campaigned it in the Sportsman class (1/4 mile drags) for 9 years. Bought an Art Carr converter that flashed to 2,800 rpm's originally. Had the car dyno tuned with timing recurve and carb jetting for more power and the car would then flash to 3,100 rpm's. Only 300 more rpm's, so it was OK.
My 2007 Mustang GT has a factory stall speed of about 2,200 rpm's. The converter I had installed was rated to flash to 3,400 to 3,600 rpm's for an all-stock GT. I had already changed tunes in the car for more power, so it actually was flashing to 3,800 to 4,000 rpm's. Then last week I installed a JLT CAI and tune, and the car feels a tad bit stronger (seat of the pants), but the converter is now flashing to about 4,300 rpm's! The air is really cold now (it's 35-40 degrees outside this week), so the air helps a bit. But, would just adding a CAI generate enough additional power to push the stall speed up that much?
Granted, peak torque in a 4.6L 3V is about where my converter is currently flashing to, so it puts me right in the thick of the powerband, but what happens if I continue modding the car? Will I eventually find it flashing to 5K or 6K rpm's? That would suck and I'd need to change converters to something mellower.
Any advice or thoughts are appreciated.
as far as you converter stall increasing as your power level goes up...isn't that good
IMO thats not a bad problem to have and you are correct in that the torque curve is right there where your stalling now so unless you add 300ft lbs. of torque i doubt you will ever get to the point where you have 5k stall but it is possible. we used to sell lots of V6 monza and vega converters to chevy guys. behind a big block they would stall upwards of 3800-4000rpms. i think when stock behind the 4 cyl or V6 they only stalled 2000-2500.
11/22/07, 10:35 PM
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Wow, good info and thanks for responding. With street tires at a stop and against the brakes I can only get to 2,800 rpm's before the tires start to move. It'll be interesting to try it at the track with drag radials, though (I use BFG 275/40/17 drag radials).
The car easily overpowers the street tires in 1st and 2nd gear, so I can't tell how high it flashes off the brakes, unless I lock it in 3rd gear, so I've been testing flash rpm's in 3rd gear while rolling down the street. Cruising at about 2000-2500 rpm's, mash the pedal and instant 4300-4400 rpm's then it goes up as the car accelerates. In 4th gear, it's the same story as long as I don't put my foot so far down as to get a downshift. That's why I only test in third gear, like you. The difference being that I'm doing it from a roll.
Ultimately, you are correct that having it flash right into peak torque is a good thing. I've been running mid 1.80's to sixty feet at the track, so it'll be interesting to see if the extra stall speed gets me into the 1.70's.
The car easily overpowers the street tires in 1st and 2nd gear, so I can't tell how high it flashes off the brakes, unless I lock it in 3rd gear, so I've been testing flash rpm's in 3rd gear while rolling down the street. Cruising at about 2000-2500 rpm's, mash the pedal and instant 4300-4400 rpm's then it goes up as the car accelerates. In 4th gear, it's the same story as long as I don't put my foot so far down as to get a downshift. That's why I only test in third gear, like you. The difference being that I'm doing it from a roll.
Ultimately, you are correct that having it flash right into peak torque is a good thing. I've been running mid 1.80's to sixty feet at the track, so it'll be interesting to see if the extra stall speed gets me into the 1.70's.
11/28/07, 08:36 AM
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A little update. I went out to powerbrake at a standstill in 3rd gear to see how many rpm's the converter is stalling to. The computer did NOT like this! It revved to about 4200 rpm's before the tires started to move against the brakes, then the car stumbled like it was going to die so I let off. The little wrench light came on (check engine light?) and the computer put the trans into safe mode which locks it into 4th gear only! The message center showed a code that read: M1---. No numbers in the code. I was only a few blocks away from home, so I parked in the driveway & cycled the ignition. Fired it up and all was fine. Plugged into the OBDII port to check the code, but there was none so it cleared by itself.
Talked to our SVT technician the following day at work and he thinks the computer didn't like the high rpm's in a forward gear with no associated mph or acceleration, so it was just protecting itself. No mechanical harm done.
Moral of the story, good thing for smart computers in our cars, and mods can dramatically affect stall speed with an aftermarket converter.
Talked to our SVT technician the following day at work and he thinks the computer didn't like the high rpm's in a forward gear with no associated mph or acceleration, so it was just protecting itself. No mechanical harm done.
Moral of the story, good thing for smart computers in our cars, and mods can dramatically affect stall speed with an aftermarket converter.
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