Tfasano

iTrader: (1)

I was wondering if anyone that has upgraded the stall speed of the torque converter can post the details of any negative affects experienced

go-g35

iTrader: (1)

I just had it done (G35 coupe) and I think its great. Its a daily driver and the rpms are pretty much normal when just driving around, but now I can easily get into the engine power band when I punch it. I have a 2700 stall. I can now put down some rubber without the ECU getting in the way.

learn2turn

Which exact TC did you get? (Brand, etc.) Did you upgrade the valve body?
Thanks

Aggro_Al

Rasing the stall too high can make daily driving uncomfortable. The transmission will want to start off at the stall speed when the throttle is pressed. This could make regular driving twitchy or jerky because RPM and torque will start out high. Also, in most cases raising the stall speed can affect your gas mileage. Since you are starting out at a higher RPM you will use more gas. If your Z is also going to be a daily driver I heard that raising it just a few hundred RPMs above the current stall speed will give you pretty good gains while still keeping your car street driveable and with very little mileage hit. If you are more interested in all out performance then raising the stall speed to just a few hundred RPMs below the engines max torque will be the most beneficial. Raising the stall to a high level or brake torquing to a high level may require that you add a tranny cooler because while the tranny is mutiplying torque or slipping it will generate a lot of heat. Heat is a torque converter's enemy. You don't want the fluid to burn or evaporate.

go-g35

iTrader: (1)

totally agree, that is why I only have a stall of 2700 rpm. Normal driving is about the same rpm wise, except now when you hit the gas you get more into the engines power band. Don't know about gas milage yet, but I'll keep you guys informed.

Tfasano

iTrader: (1)

Do you notice any difference at all from a dead stop during normal driving? By that I mean slower driving, I am not sure what is normal for you, haha.

go-g35

iTrader: (1)

not really, I drive it everyday so yes I notice the difference, but it is only because I know the stall is higher. 55mph driving the rpms are just about the same as before maybe a little higher, but only like 100 rpm's or so.

Tfasano

iTrader: (1)

The difference I am asking about is from a dead stop, the transmission will engage at a higher rpm. Some say it will jerk around a bit. Notice this at all?

go-g35

iTrader: (1)

None. The car drives normal.

learn2turn

Price ? Brand? Upgraded valvebody?

go-g35

iTrader: (1)

Stock converter. No valvebody upgrade yet.

learn2turn

How about the price and brand.

shopdog

Ok, you still have the stock converter. So how did they raise the stall speed? Grind away some of the vanes?

Note that you can change the lock up RPM with Consult II, but the only way to change the stall speed is to swap in a different converter or modify the stock one. The latter is sort of a shade tree mod, and not recommended.

go-g35

iTrader: (1)

I had a 30 year veteran of torque converters do the mod, it took him a one full day to do it. He said that the highest he could confidently go was 2700, tops, with this converter. You can even call Edge racing torque converters and they will tell you the same thing. A torque converter is a torque converter no matter who makes it, they all work the same.
I have no regrets with this mod, it has given my car that shot in the arm that is definately needed. Keeping the car under 2500rpm when driving, the car drives exactly the same. Only now when I punch it, it takes off like a bat out of hell.

Tfasano

iTrader: (1)

Thanks, thats all I needed to hear. Sign me up!

Aggro_Al

TFasano,

If the stall is set just a little bit higher than the current stall speed you won't notice much of difference in normal driving. You'll notice it most when you create a big difference between the impeller (engine input) and turbine (driveshaft output) speeds. The bigger the difference, the more torque that will be created. Because a torque converter mulitplies or creates torque, setting the stall speed to a higher level will allow the torque converter to create a bigger difference between the impeller and turbine speeds. It is possible to put down more torque at the wheels than the engine is currently producing with a torque converter. There are a few ways you can create this difference but, in most cases, you'll create the biggest speed difference when you're rapidly accelerating from a stop or brake torquing.

shopdog

Ok, I just wanted to make it clear to everyone that the stall speed is not a "setting" or "adjustment". You have to physically modify or replace the torque converter to get a different stall speed.

If you choose modification, you need someone who *really* knows what he's doing to do it. The torque converter rotates at engine RPM, so even the slightest imbalance created when you modify the vanes will cause big trouble.