Pretty stupid question, but what do torque converters do? I see them talked about a lot on this site but I still dont know what they do. I ask because I have a 700R4, and from what i've gathered they obviously dont hurt performance.

 

basically it's a hydrolic coupling device, connects the engine to the trans.

 

In that coupling that ede described fluid momentum is used to turn your tranny. When you hear of different RPM ratings for converters that depends on the amount the converter will slip before it connects all the way, sorta speak. Does that make sense? That is about as non technical as you can get.

 

go to www.howthingswork.com and you ought to get a better idea along with a pic or two

 

imagine having two fans facing each other.

one fan is plugged in. the other one isnt.



the plugged in fan moves the air over the unplugged fan, and the fan turns.

the plugged in fan can keep turning even if the unplugged one isnt.



this is the same BASIC concept as the TQ converter. it takes the spinning motor and uses the movement of hyd fluid to connect the power to the trans...


in our fan example, the motor is the plugged in fan, and the drivetrain is the unplugged one.



get it?

 

yeah that seems to make sense, thanks a lot guys! Those pictures were quite helpful.

Why would you want it to slip at all? It seems like you'de want it to connect all the way the whole time. Is it sorta like how you let the clutch out? What I mean by that is, ya know how you start moving before you let the clutch completly out making it so that your not completly engaged until a certain speed? (not like it's incredibly noticable, but if you think about it you'll know what i mean) I'm not sure if im making sense right now, but I tried

 

Dump the clutch with no gas, and then slip it out at 2500. What gets you off the line faster? Same basic concept.

 

You want it to slip a bit while your engine revs to the start of its power band. It is like feathering the clutch when you drive. You don't just dump it everytime or you will only spin your tires. You roll off the line to maximise traction while your engine builds to its power band.

 

you want it to slip sometimes.

for example, at a stoplight.. the engine still must turn (to idle) but the car isnt moving.


the reason for "looser" converters at the drag strip is simple... lets say at idle your car makes 15hp... at 1500rpm it makes 170, and at 3000 it makes 250.
if you just connected the two, the motor would have to pull thru the lower 1500 power, until it reaches the higher RPMs and makes more power.
with the looser converter, the car hasnt moved yet, but the motor can sit at 3000... making more power, so when you let off the brake, the car launches forward harder.


meanwhile going down the hwy, you DONT want them to slip. our cars actually have a clutch in the converter that locks it to the motor.. its computer controlled so it knows when to come on and shut off... if you ever had it stay on when you come to a stop, it would stall the car...



again, this is a very BASIC example. but should give you the general concept.

 

ahhh ok yeah it's a pretty simple concept then... thanks for clearing that up for me

So lets say i got a cam that makes power from 2800-5500.. would I want a TQ converter with a 2800 stall to get me into my powerband quickly? (random numbers... just an example)

 

Now you got it. That stall may be a bit high but you are deff on the right track. That stall would be perfect if you had the right gears and such. Most manufacturers of cams will recomend a certain stall if you call them.

 

yup... you got it.



now read the manual Vs automatic in drag racing threads, and chuckle at thoes who think a "more direct connection" with a manual will be faster on the dragstrip.

 

Alright, well thanks for the help guys this stuff is actually starting to make sense now