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How to chose nice torq convertor

1526 Views 13 Replies 5 Participants Last post by  red65mustang, 
B
Many people use shift kit with torq converter stall . I would like to know how it's work . what wanna mean 1800-2200 or thing like that.how to chose the good converter . Thank
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R
A higher stall convertor most directly relates to the cam you choose and where is the power band of the cam and motor.

Ex:
Edelbrock performer cam = 0- 5,000 = stock convertor

Edelbrock torker plus cam = 2500-6500 = you gotta have a higher stall convertor.

A higher stall convertor and a small cam can make a street car yuch....

The basic idea of a shift kit is, mostly by increasing and decreasing the fluid flow rate and pressure thru the valve body you change gears much faster. Same as ? shifting a stick with out using the clutch
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M
converter stall

Converter stall, being the RPM your engine will not exceed when you have your transmission in gear, the brakes set, and the throttle on the floor, is determined by two factors. Mainly the size and design of the converter, but also in large part, the amount of torque the engine produces.
Converter Flash is where when sitting on level ground, in gear, no brakes, the RPM required to start the vehicle moving, which is a lot lower than the stall speed.

Example: Once had a 69 Mustang with a 302. When the engine was stock, it stalled at 17-1800 RPM, after I built up the engine a bit, the stall went up to 20-2100. This was due to the increased amount of torque the engine put out.

Picking the proper stall for your engine combination, is mostly based on the engines power band.

As mentioned by red65, a bigger cam requires a higher stall, in order to best utilize your power band.

Other factors involved are the majority of how the car is driven. If you have a hopped up engine in a car that is generally a stop light grand prix, and daily driver, you wont want to put quite as high a stall in it as you would for if you were just racing the car every weekend. Daily driveability is a factor, as well as wear and tear on parts.
High stall converters generate more heat due to more slippage before flashing and stalling, causing additional wear and tear on the transmission.

For instance, if you have an engine that has peak torque at 3500 RPM, you wont want a 3500 stall converter for street use, but something more along the line of a 2000-2500 rpm. , just to make it more streetable.
Hope this helps some.

Picking a converter depends on your engine setup, car weight, differential gearing and whether you have a posi type rear end or not. More of that data would be helpful
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D
:D


I suggest you calling the converter manufacturer of your choice and asking THEM......They do this for a living. They WANT you to be HAPPY..so they will get referrals from you.

That's what I always do....ask the people who make them.

:cool:
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B
convertor choice

The shift kit allows the tranny to shift quicker and deliver more pressure to the friction plates. Thus less tranny slip.

Stall: If you tied your car to a tree and stepped on the brakes and put the accelerator to the floor. The car will raise in rpm until the covertor causes the tranny to lock up and stall the motor. The looser the convertor the higher the motor can rev before it will stall. Thus high stall convertor. The rpm where the engine conks out is the stall rating given the convertor.

Advantage: Cams are designed to start working at a certain rpm. The faster your motor can get to that rpm at the starting line. The faster your car will make hp. The motor can spin up to the tranny lock up point faster with a looser convertor. This is known as flashing the convertor.

Choosing the convertor: When purchasing a cam. The ad, will tell you lift, duration, centerline, RPM window, and what convertor to use.

Choosing a cam: Depends on head and intake choice.
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M
stall speed

When the engine is run up to stall against the torque converter, with the brakes on, the engine will run up to a certain rpm and no more. It does not kill the engine.

And yes, when choosing a torque converter, it is best to find out what the manufacturer suggests for your setup, as was mentioned.
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B
engine doesn't stall

Why does MSD put secondary rev limiters in the digital 6 box? Why call it stall, why not call it the "engine won't rev anymorer"?
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M
rev limiter

A rev limiter is to prevent running the engine over a specific rpm. when you hit the top of a rev limiter it partially cuts out your ignition so you cant turn the engine any tighter. Some have a auto kill switch in them but dont know of anyone that uses that setup.
A rev limiter will not hold the car in place while torque braking at the starting line.

Most of the pro drag racers, that use automatic transmissions run trans brakes now instead of using their foot brake to hold the car on the line with the engine revved up against the torque converter.
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B
yes

Its to keep the engine revving up to stall and killing the motor.
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M
rev limiter

Well, I dont know why its called the stall speed other than the engine is stalled at a particular RPM, and wont turn any higher.
I dont know a lot about MSD ignition systems, but they dont have anything to do with brakes and torque converter stall.
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B
Thanks to everybody this informations really helped me to understand tork . I don't understand english very well(I talk french)but I will ask to someone for some words I not sure .You talk clearly and I will ask you later for my engine set-up probably with a mini blower. Thanks again
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B
sorry

Your right the engine won't stall. got confused with tranny brake set up.
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M
rev limiter

Im not sure what the point is you are trying to make here Bracketeer.
I can only presume you have never drag raced with an automatic transmission, and brought the engine up against the torque converter with the brakes on, at the starting line.
Why would you want to kill the motor when you are trying to race.

Try going back and rereading the entire thread.

You are welcome Bandit, any time.
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R
Bandit,

your welcome

Do call several of the different torque convertor mfgr's when you are ready.

They need to know "everything" about your car: weight,/gears/tires/etc. Have that handy when you call.

Matching the cam to the convertor only gets you to the right page to select from.......

Thought your question was "why use a different convertor"

I over simplified with my answer.....
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