I get that. I just don’t know what the deal is with diameters vs what there used for and in. I do know that faster cars will have smaller converters. Less fluid inside to move? Would be the reason I guess.
Most of it has to do with efficiency. The housing and stator change stall speed and efficiency, plus the fin angle and some other stuff.
I’m WAY out of my comfort zone with converters. The little I do know I just posted.
For the chevy truck I just did the tunnel ram deal on the discussion between myself and PTC went back and forth on two things. One was what housing and stator diameter to use, and was my buddy going to run a big enough oil cooler to deal with what we needed.
To that end, the question was do we use a 9 inch housing and a 9 inch stator, a 9 inch housing and an 8 inch stator, or an 8 inch housing and an 8 inch stator.
In the end, it was the 8 and 8 combo. He has an oil cooler that was more than capable.
I know Tim at PTC was concerned that the stall was where it should be, and that the converter wouldn’t slip while driving it on the street, which makes a ton of heat. So that was why the 8 or 9 inch stator was in question.
As for using a bigger housing, if you’ve ever seen a power adder car “drive through” the converter because the power is high enough the little housing can’t deal with it, then you know that the housing and stator are too small.
Torque makes stall. So the 8/8 in my buddy’s truck which is 5100 flash stall with his N/A small block would probably gain (just going to guess here so don’t hold me to hard numbers) 500-600 RPM stall behind say a tunnel ram 572 engine with the exact same converter.
If that is too high, then you have to increase the case size and stator to get the stall speed back where you need it.
Now take that same 572 and add the hose to it or a pair of hair dryers and the added torque just makes the stall speed go up.
Vehicle weight matters too. The lighter the car, the smaller the case to get the same stall speed, IIRC.
That fully taps out what little understanding of torque converters I have. One thing I’m positive on is that torque converters have come a BILLION miles from where they were when I started driving/racing in 1980. A BILLION miles. Today what companies like PTC, A-1...now I can’t think of some of the better companies...the dude that started the bolt together stuff...what they do is phenomenal. It’s nothing like it used to be.
In 1985 if someone told me they were using an 8 inch converter on a 75% STREET driven car, they’d have locked you up in a padded room. That was unthinkable. Today it is very mundane.
