[red102793]

I was wondering what a high stall torque converter does? I'm in the middle of a 5.0 conversion and I'm using an AOD, I'd love to do a 5 speed but it's a really tight budget. I've seen lots of people that have high stall converters in there autos and I've also heard of a manuel valvebody if someone could explain what these do and are it would be greatly appericated.

[fordman777]

If you've read about manual transmissions, you know that an engine is connected to a transmission by way of a clutch. Without this connection, a car would not be able to come to a complete stop without killing the engine. But cars with an automatic transmission have no clutch that disconnects the transmission from the engine. Instead, they use an amazing device called a torque converter. It may not look like much, but there are some very interesting things going on inside.


The Basics


Just like manual transmission cars, cars with automatic transmissions need a way to let the engine turn while the wheels and gears in the transmission come to a stop. Manual transmission cars use a clutch, which completely disconnects the engine from the transmission. Automatic transmission cars use a torque converter.

A torque converter is a type of fluid coupling, which allows the engine to spin somewhat independently of the transmission. If the engine is turning slowly, such as when the car is idling at a stoplight, the amount of torque passed through the torque converter is very small, so keeping the car still requires only a light pressure on the brake pedal. If you were to step on the gas pedal while the car is stopped, you would have to press harder on the brake to keep the car from moving. This is because when you step on the gas, the engine speeds up and pumps more fluid into the torque converter, causing more torque to be transmitted to the wheels.

Im not going to tell you what to do but take this into consideration! Lets say you got a 2500 stall converter your not going to move till you get to 2500 rpm so its kind of rough on a tranny to do this expecially a stock aod if thats what you got they are notorious for many parts failing! If you want a high stall converter I suggest you get a good used c4 or if you got the money but you said you was on budget so you cant get an aftermarket aod thats pretty much bullet proof compared to stock and will withstand at least 500 hp!

Good Luck and hope this helps!

[EagleAutosports]

That's a good explanation, I'll expand on it.

The stall speed of a converter is determined by several things. A converter is made up of 4 parts, the front cover, stator, impeller, and rear cover. Each part has fins inside it to direct the fluid around each part and by modifying these fin's angle, it changes the stall speed. Stall speed is essentially when the engine speed and fluid speed are the same, and stall speed is NOT when you're sitting at a stop and mash the gas while holding the brake. That rpm is NOT the stall speed, that's just where the engine torque overpowers the brakes and moves the car forward.
A higher stall speed allows the engine to get into the powerband quicker, like revving a clutch and quickly slipping it. Unlike a clutch, a converter doesn't get grabby or tempermental. But a higher stall speed creates more fluid slippage inside it, creating more heat so an auxiliary trans cooler should be considered mandatory.
A higher stall speed can also take the shock out of the drivetrain when the trans shifts, making it actually easier on parts.
The stall speed can also be affected by the engine it's behind. A converter that stalls at 2000 behind a stock small block could stall at 3800 behind a big block. This is why converters should be custom made for your combination for the best performance.

A manual valvebody is just that, manual. There is NO automatic shifting features in the trans anymore, if you stop with it in third and not pull it into first, you'll take off in third. Think of it as a manual trans without a clutch. I have one and the AOD really wakes up with one, I won't have another automatic AOD.

[rj8806]

Great description fordman...the way they wrote it makes it easy for anyone to understand.In fact, It sounded an awful lot like this HowStuffWorks "How Torque Converters Work"


be sure to give credit where credit is due that way no one comes after you for plagiarizing.

[red102793]

Thanks a lot guys I defentily have to look into a manuel valvebody and a high stall