The Converter Thread

[Bersaglieri]

I selected my current torque converter out of sheer necessity, good price, and a total lack of prior knowledge. My converter works well for some tasks and poorly for others. Problem is the "others" is that I do 90% of the time.

I decided next time I wasn't going to just blindly buy something out because of a company name, or because it was the trend, or because it was cheap. Although in my search to make an educated buy, I've found a general lack of information and understanding of torque converters for our trucks. I've spoke with numerous companies who lack the ability to explain to me the approximate flash and/or brake stall of the converter they want to sell me. So I figured we could start getting the information public on individual setups to help everyone better select the converter that best suits their needs. Please cite any relevant information about your setup, 12v/24v/CR, gearing, HP/TQ [even if it's an estimate], turbo and fueling modifications. Also list the converter brand, part number and/or stator setup, and of course the flash and/or brake [true stall] speeds.

I'll start, just copy and paste this format and insert your info.

Brand: DTT
Model/Part: 89% "old blue" Single Disc [Race version]
Flash Stall: 1200-1250rpm
Brake Stall [True]: 1700-1800rpm
Truck Setup 12v, 3.54, HX35/HT3B, 5x.014 injectors, 181's
HP/TQ: ~500/1000
Additional Info: Converter has a stock stamped front cover and welded bolt mounts. Because of the low flash stall moving a heavy trailer from a stop can be smokey and difficult, although the converter is perfect for track use and spooling at the line. Single disc holds truck's power well, although when hauling a heavy load can I've encountered converter "bounce" upon lockup.

Borrowed from Goerend about stall speeds:

To explain "stall speed", lets start with a true full stall. If the transmission were in drive, the brakes were held down (so the vehicle will not move) and the throttle was held "wide open" the torque converter will "stall" the engine at a certain rpm. When "stalled" the engine will not be able to spin any faster unless the vehicle is allowed to move. This is a true full stall. We have specialized equipment which is used to perform this test.

DO NOT TEST FOR TRUE STALL, IT CAN DAMAGE SHAFTS AND OVERHEAT THE TORQUE CONVERTER!

The next stall speed is generally called "break away" stall speed. If a truck is stopped on a hill and held in position using light throttle as opposed to brakes we are almost at the "break away" stall speed. If the engine rpm required to "hold" the truck was 1100 rpm and an increase to 1125 rpm started to move the truck then the "break away" stall speed is 1125 rpm.

The last stall speed is generally referred to as the "flash stall" speed. The flash stall speed takes effect under hard acceleration. If, from a standing start, you were to "floor" the throttle the engine would start to accelerate quickly and then pause at an rpm is it starts to pull the truck. If the engine went from idle to 1500 rpm in 1.5 seconds when floored and then took another 2 or 3 seconds to get from 1500 to 1700 rpm, this would mean the "flash stall" speed was at 1500 rpm. When we lower the stall we want to lower the break away speed as well as the flash stall speed. This will make the engine work at a lower rpm for a given road speed and, in most cases, will increase fuel mileage.

Once up to speed, the computer will command the lock up clutch "on", and the driven fan will lock to the front cover of the converter. At this point the drive, driven fan and engine are turning the same speed which means all engine power will be delivered to the transmission and back to the wheels.

-Dustin-

 

[mondtster]

...Although in my search to make an educated buy, I've found a general lack of information and understanding of torque converters for our trucks. I've spoke with numerous companies who lack the ability to explain to me the approximate flash and/or brake stall of the converter they want to sell me.

There's probably a reason they can't tell you the numbers you want to know. It has to deal with the fact that the exact same torque converter can (and will) act differently behind different engines and in different vehicles.

IMHO the cheap torque converter manufacturers (like what gets sold in Summit and Jegs) have done the industry a disservice by listing their converters with stall ratings. Now everyone asks the question "what stall am I getting?" or "what stall is your converter?" when they should be just taking what they get from a top line manufacturer, trying it out, and if it doesn't meet their needs calling the shop back with good data and making adjustments from there.

I don't think you're going to have any better luck finding the answers you want on a web forum.

Have you researched torque converter theory and gotten an understanding on what each part does so you can have a good in depth conversation with a converter builder?

 

[Timebomb]

We would have better luck do to knowledge base, if we had a gas engine. I had a converter speced to my Comet and it was right on the money were he said flash stall would be. That converter was built based off of every ounce of info about the cars setup from head flow numbers to final drive gear ratio. Everything has an effect on stall speed.

 

[Bersaglieri]

There's probably a reason they can't tell you the numbers you want to know. It has to deal with the fact that the exact same torque converter can (and will) act differently behind different engines and in different vehicles.

IMHO the cheap torque converter manufacturers (like what gets sold in Summit and Jegs) have done the industry a disservice by listing their converters with stall ratings. Now everyone asks the question "what stall am I getting?" or "what stall is your converter?" when they should be just taking what they get from a top line manufacturer, trying it out, and if it doesn't meet their needs calling the shop back with good data and making adjustments from there.

I don't think you're going to have any better luck finding the answers you want on a web forum.

Have you researched torque converter theory and gotten an understanding on what each part does so you can have a good in depth conversation with a converter builder?

Yes, I already know this. Hence why I'd like to get some of this "good data" AKA real life data on how certain stalls act in conjunction with certain setups. We can't all get custom converters built, which is also why I'm trying to organize some information on some typically off the shelf converters. I figured it would also give people better info for having converters built when some of the Goerend guys post up there stator setup, etc.

-Dustin-

 

[mondtster]

Yes, I already know this. Hence why I'd like to get some of this "good data" AKA real life data on how certain stalls act in conjunction with certain setups.

Your clarification makes a bit more sense, but I still feel that the information you receive isn't going to be very useful. There's way too many variables with converters and the vehicles they're installed in to get any type of good information to apply it to another setup. Then add in people's personal opinion on what is a good setup and that muddies the water even more.

We can't all get custom converters built, which is also why I'm trying to organize some information on some typically off the shelf converters. I figured it would also give people better info for having converters built when some of the Goerend guys post up there stator setup, etc.

So you're basically wanting to get free information from the guys willing to spend the money on a Goerend (or other similar vendors) converter and go buy a cheap one that somewhat resembles it? That's how I read it at least...

 

[joefarmer]

Yes, I already know this. Hence why I'd like to get some of this "good data" AKA real life data on how certain stalls act in conjunction with certain setups. We can't all get custom converters built, which is also why I'm trying to organize some information on some typically off the shelf converters. I figured it would also give people better info for having converters built when some of the Goerend guys post up there stator setup, etc.

-Dustin-

Actually, you can get a custom stall converter built without breaking the bank. Goerend worked with my wacky race setup (4k lbs, custom header, non-ported head, radical timing, etc) and he found the sweet spot after the second one. He was fairly close on the first converter and it needed minor tweaks to run an extra 6* of timing. All it cost me was the normal price and $75 to ship it the second time. Call Dave, his 45-60minute 'interview' is well worth your time. He builds enough of these that not many scenarios stump him.

 

[Blacksdieselhp]

Yea, I'd say Dave Goerend would be your best bet if your trying to find a converter you like. He will give you more knowledge than your gonna want over the phone and then if you get the converter and it isnt exactly what you want/need, he'll just send you another one of your choice and all you have to do is pay shipping and send that one back.