[Horsepower69]

I have heard many explanations of what "stall speed" is and i'm still confused. Correct me if i'm wrong but....It is to my understanding that the stall speed is when you fully lock the brakes, floor the accelerator and the rpm at which the wheels start to spin is called the stall speed. This part makes sense to me but here's the part where i hope you will be so kind as to help me out. I've read that a 4000 stall converter behind a big block 502 will produce a stall speed of 1700 behind a 283. I don't see how this is possible since the 283 has very little low end torque. Wouldn't it make more sense that the 502 would be more likely to spin the tires at 1700 rpm?? I hope you can clear this up for me.

Thank you
Pete

 

[lev]

To the best of my knowledge, stall speed is at what RPM the converter will utilize ALL the torque that it's given to drive the tranny. Until then, it's kinda like having the clutch out. The reason that a converter behind a big block will produce X amount of stall and far less with a much milder engine is that how well a converter works is proportional to how much torque you feed 'em. The fluid in there's spinning, the harder you spin it, the more torque it transfers, the harder it is for it to pass it on. That's why they provide full effect at higher RPM. If you put the same converter behind a milder engine, it'll be able to fully engage quicker.
That's the way I see it. It may not be the correct way, though

------------------
70 Malibu
350/300hp
Soon to be 396/325hp

 

[BAD415]

I agree.

 

[lev]

Woohooo!!! Torque converters are like black holes to me. I just kinda know what they do. Recently I've been interested in how and why, so I did some research. Seems it MAY be paying off.

 

[67drake]

If I could add .02 here.I think what may be confusing you is the "spin the tires" thinking.This is not actually correct.Try thinking of it this way.Stall speed is the maximum RPM that your engine is at while at full throttle,but before the car is in motion.(I don't know how else to word it!)A common way to measure this is to do as you mentioned-Hold the brake,floor the throttle.MOST performance cars at this point almost immediately spin thier tires,because the engines torque overrides the brakes.But the RPM that is reached BEFORE the tires break loose is your stall speed.I don't know if this makes it any clearer,but if it does then go back and read the above posts and it should make sense.
Let me also add this. Going by your(Horsepower69)definition of stall speed,What if you had a car with a slug 4 cyl. engine,low numerical gear,good brakes.You could stand on the gas and brake all day and the tires would never spin.So of coarse you would'nt say that the torque convertor has NO stall speed.Hope this helps.If my answers are wrong I hope someone fills us in.

[This message has been edited by 67drake (edited 02-02-2000).]

[This message has been edited by 67drake (edited 02-02-2000).]