Killed a chevy...

[TatII]

is there any kind of proof of this? i know by installing a torque converter with a higher stall speed, you can rev the engine up to the stall speed then just let off the brake and your good to go. however i've never heard of it actually increasing torque past the crank to the tranny since there aren't exactly gears in the thing. its basically a turbine, a stator, and a impeller. all it does it throw fluid around at high speed to remove the other side of the torque converter around. this does not give a 100% lock. therefore less power will make it to the tranny compared to a 5 speed. that is also why the computer on cars now lock the torque converter together when its in overdrive to save gas.

the reason why people use automatic's is during bracket racing where people compete right down to the 1000th second. so consistancy is the key. you will have a much more consistant launch with auto with a 2 step vs. a manny with a 2 step.

however there is one thing that sorta throws off that theory which is on turbo cars, off the line you hit the brake and spool the turbo up.

but however i doubt that its actually mulitplying torque. i feel that its more of "your loading up the engine by not letting it move to spool the thing up"

if you have articles of what you said. then i'll gladly read it and learn something new.

[CivRacer95]

Nice Kill. Despite that is was a Cavvy, they're not all bad. I've raced a few. I've lost to some, and won some. Either way, he still shouldn't have flipped you off. You gave the Thumbs Up showing good sport and he decided to be a bad sport. That's stupid when someone can't accept the fact they lost to a faster car. late...

[chevytrucks92]

Originally Posted by TatII

the reason why people use automatic's is during bracket racing where people compete right down to the 1000th second. so consistancy is the key. you will have a much more consistant launch with auto with a 2 step vs. a manny with a 2 step.

That is correct. In fact, if you ever won a bracket race with a manual, it would be pure luck (I'm talking about in the top bracket now, where street cars are not allowed and all electronic devices are).

I have a 5000 stall Converter in the car pictured in my sig, but I leave the line only at 3400 rpms (short wheel base + high torque = wheelies).

Anyways, in a serious bracket car, you have a transmission brake (locks the tranny in 1st and reverse), a delay box (delays the launch of the car, this helps in getting consistant reaction times), and a three-step rev limiter (or two-step) and of course a high stall converter.

Now about converters in general, I've never heard of this "torque multiplication" thing either. I would agree that a high stall converter would be better then a manual for launching. I mean you can bring the engine up to a certain RPM without the transmission pulling, so you get the same effect (pretty much) as holding the clutch and bringing the RPMs up.

I think that is just a rumor, since they are called torque converters, but I really don't know.

I do know this: get in a car with a high stall converter (like a race car) and just be sort of letting it idle to the staging lanes, and start up a small hill (where I race, the staging lanes end with a small hill that turns you into the track), and you'll think a 4-cylinder street car has more power, lol.

[dcaegis]

yes, guys, the torque converter definetly multiplies torque and this is due to SLIPPAGE

the actual fluid area inside a torque converter looks something like a doughnut. this is sliced in half, one side connects to the motor, the other side to the tranny, and their are veins inside to force fluid flow. when the input side rotates, it pumps fluid by slinging to the outside of the converter. the only place the fluid can go from there is back towards the middle by travelling on the output side. this creates a swirling motion; the fluid traveling towards the center on the output side pushes agianst the veins mounted to the output side and this is what causes it to turn.

slippage accurs because the torque converter is not 100% efficient. the input side always has to be turning faster than the output side because of losses in the fluid. the difference in speed between the input and output side of the coupling is the "slippage". torque multiplication is directly proportional to the amount of slippage.

If you think of the input side as "pumping" fluid the output side, then is logical that (assuming 100% efficeincy) if the input is pumping at a certain speed, and then output is turning at the same speed, 100% of the torque is getting transferred. however, if the output side slows and the input side continues rotating at the same speed, then it is now pumping more fluid than is necissary to maintain that output speed. because of this, more pressure builds up in the fluid and the torque on the output side is increased until it speeds up to the speed of the input.

so, assuming 100% efficiency, if your engine is rotating at twice the speed of your transmission, torque multiplication is 200%. If your engine is turning and the transmission is completely still, then torque multiplication would be infinite. we all know this isnt the case, and that's because of the inefficiency inherant in a fluid coupling and the fluid can squeeze through the gap between the input and output side.

there is a point if the input side is turning fast enough, where fluid motion will become turbulent and the torque converter effectively locks up. this is the "stall speed"

hopefully this helps clear up some confusion.

[duplox]

"Benefits and Weak Points
In addition to the very important job of allowing your car come to a complete stop without stalling the engine, the torque converter actually gives your car more torque when you accelerate out of a stop. Modern torque converters can multiply the torque of the engine by two to three times. This effect only happens when the engine is turning much faster than the transmission."
http://auto.howstuffworks.com/torque-converter3.htm

[PearlGT]

manuals always take automatics off the line from what I've seen (with the exception of those built up automatic transmissions w/ high stall converters). Manuals have a clutch which enables the person to actually launch the car from a higher rpm instead of just floor it from a lower rpm. Maybe I could see how a torque converter could be very beneficial to your launch on a very built up car but I don't see how it works out other wise.