Airman21

I have a Torque Converter on my 01 Mustang GT and was wondering if there is a way to tell what the stall is set at? This was already installed on my car when I bought it. I don't remember if he told me and I forgot, or if I never asked what it was set at. I remember hearing something about holding the brake down and giving it gas untill it "feels" like it wants to go.. Any merit to this? Thanks!

tbirdscwd

Put it in 1st, get a 15-20mph roll going and nail it. You should see the rpms jump up to a certain point and slow down dramatically The rpm might even hover at tis point for a few seconds til the car's speed catches up with the converter slipping. That point is where your converter flashes to aka your stall speed. You need to make sure you don't break traction though otherwise you will see a higher number due to the wheel spin

What you are describing is called foot braking the car. This isn't a good indicator of your true stall speed. Stall speed is usually rated for what the converter will flash to on a transbrake which is much different than using the foot brake. For example, my car has a stall speed of about 4500rpm, but anything above 3,000 on the foot brake will break my street tires loose. I can get a bit higher on my hoosiers, but nowhere near 4500.

Airman21

Thanks for your reply. I have 4.10 gears and shift kit as well so I dont know if that will still be something I can do. Going 15-20 in 1st will be pretty high RPM's. I will try that out tomarrow and see if I can figure it out. I am getting ready to order the SCT x3 flash tuner from american muscle and wanted to make sure I give them all the details for the custom tunes that come with it.

tbirdscwd

You can try it in higher gears, but sometimes the car will kick down into a lower gear depending on your speed. I have 4.10s too which makes it a bit harder (well not harder, just faster). Try it in second if 1st won't work for you. 2nd will be good if you have a shift kit with a true manual valve installed.

Hangwire

Good thread i'm watching this one. I wish I could launch with a lot more power than I can with my stock converter. At stock I could find that sweet spot and hook about once every five tries or so but with a blower its just spin control until i'm going fast enough to bust it WOT, at which point babies die.

Tbird explain what the effects are on everyday driving with a 4500 stall as if I were a five year old. No matter how much I read about converters I just cant seem to get a great concept of what they do outside of slip a lot more until your engine RPM matches tranny RPM on launch(I believe you are calling this the "flash" point).

tbirdscwd

Daily driving or Street driving really isn't affected much at all with the 4r70w. The converters we use are lock-up converters which means they have a set of clutches and a piston which actuates these clutches inside the converter actually locking the converter under cruising conditions. Even if you are well below the stall or flash speed.

The only difference for daily use is that it takes a little more throttle off the line to get the car moving. It kind of just feels like your car weighs a lot more at really low speeds. But as soon as you give the car a little throttle, the car takes off.

There is a misconception that a converter with a higher stall just will sit there not moving until you reach that engine speed. It's just not true. The stock converter has a stall speed of like 1800, but you car will certainly move before that point. The stall speed is like you said, the point at which the engine speed is matched to the input shaft speed and stays "locked." up until that point, the engine and converter will be spinning faster than the input shaft in a process called flashing. During the time when a converter is flashing it is actually multiplying the torque output of the engine. For example, right off the line I floor the gas.....my rpms jump up to 4500 even though my car isn't physically moving at the speed that 4500 translates to in 1st gear. That is my converters flash speed. All the way up to the point where my car's speed catches up to my engine rpm, my converter is actually multiplying my engines torque output by a factor of about 2.5!!! This is one of the ways an auto really has the upper hand. And my car does this without the violent hit of a high rpm clutch drop which is required to even come close to yielding similar results.

One thing to remember is that not every converter will stall or flash at the same speed if installed on different cars. The stall and flash speed is directly correlated to how much torque you apply to the converter. An engine with higher torque will cause the same converter to stall or flash to a higher rpm. And the same goes the other way. This is why it is extremely important to have a converter buoy for YOUR car. You cannot just install a "3500 stall converter" on any car and expect it to stall at 350rpm. It doesn't work that way. A converter needs to be built to stall at a certain rpm based on your cars actual power/torque output.

dwtjr3

so what stall would you recommend with shift kit, 4.10's, CMS stage one N/A cams, and a 100-125 shot plate kit?

tbirdscwd

That build sounds extremely similar to what I told Alan over at DirtyDog when he custom built me my converter. He set me up with a custom 9.5" 4,000 stall with a billet front cover which is just re-enforcement for the extra torque nitrous will give you. He might recommend going with a 10" 3800 because you are still running the stock bottom end. That is also a very solid converter and probably better for a car that sees a ton of street time as well. It basically behaves just like a stock converter, where the 9.5" is a little more sluggish, but offers a little more track performance.

9 times out of 10, a DirtyDog 3800-4000 10" is the right choice for these cars, but I'd give Alan a call and see what he recommends.

stealth_GT

RE: tbirdscwd: Great info on torque converters

I plan on getting a 3000k stall and one piece light weight drive-shaft on my 08 to cut some killer 60 fts.

WannaBeGearHead

Alan at Dirty Dog built me a 10" 3800 stall. He said it would only be good for around 450ft/lbs but only because I didn't go with a billet front cover, which I would recommend you getting.

And don't let anyone tell you a 3800 stall is too high for DD. Mine probably is closer to 4000 and still very drivable.