Weight and the converter

[63corvette]

Originally Posted by Chris Hill

This is something that has always made me wonder. What are the actual physics involved to cause a converter's stall?

At least in our cars, the engine goes past the torque peak then settles down at a lower torque value for flash/stall. And keeping everything equal with gearing and weight, in good air it will flash at a higher rpm with increased torque.

Chris remember in good air the engine is making more HP and Torque which explains the higher rpm flash.
My 2 Cents
Rick Cates

[Chris Hill]

I agree with the higher hp and torque with better air.

But does XYZ converter stall at say 500 ft lbs no matter what? When you have better air, lets say the torque curve shifts up 10 ft*lbs. What is the phyiscs that sets stall speed? Or is it actually a stall torque that fits particular engines differently due to the engines torque curve?

So in better air, you have to increase rpm more until the torque drops off to the 500 ft*lb value, hence higher stall speed.

[danny waters sr]

Here is an experience and example of good and bad air vs rpm.
We had a 8.90 car on a throttle-stop and when it went on the stop we had it set at 3800.
Each morning we would check and set it to the same rpm and a lot of times it would be diff due to air quality. We would even check it during the day and sometimes it would be diff due to air change. A lot of people could not figure why their cars would not run the same on day as it did the next (although they would just change the time in the timer to compensate)... tere is a diff in most cases.My little 283 will change quicker than most combos due to little carb and such....

[Mark Yacavone]

Originally Posted by Chris Hill

I agree with the higher hp and torque with better air.

But does XYZ converter stall at say 500 ft lbs no matter what? When you have better air, lets say the torque curve shifts up 10 ft*lbs. What is the phyiscs that sets stall speed? Or is it actually a stall torque that fits particular engines differently due to the engines torque curve?

So in better air, you have to increase rpm more until the torque drops off to the 500 ft*lb value, hence higher stall speed.

Chris , I could give you an answer ,but I don't know how to explain it in technical terms.
It's kinda like, I know that Christina Hendricks works for me, but I can't put that in words either. LOL
It has to do with hydraulic pressure, generated centrifugally and the shear, or over -ride point.
Maybe we need an engineer to explain it. Rusty 3011?

[Joe DeMarzo]

Lenny from Ultimate where are you when we need you. This is good stuff.

[Adger Smith]

Yes Mark,
It is all explained in Fluid Dynamics. Anyone beside me still have their College books? Chris?
A good converter guy that understands it can do all kinds of nice things to a converter. It is just like with a camshaft: There is more to it than lift and duration. Same thing for converters: more to it than slip, stall and flash.

[Chris Hill]

Fluid coupling is also known as a turbine, brain fart at my end. My fluid dynamics book has maybe 10 pages if that. I'll review it tommorow and see if it makes more sense then.

Thanks for jogging my memory Adger.

[Adger Smith]

Chris,
I knew you would remember it!
Pay close attention to fluid velocity. I bet there are a few interesting refrences to it.
When I was working with Jet boats and racing them I kept my old books on my headboard. Wrong wife #2 couldn't understand what/why I was reading in the middle of the night making notes. :~)

[Mark Yacavone]

Originally Posted by Chris Hill

Fluid coupling is also known as a turbine, brain fart at my end. My fluid dynamics book has maybe 10 pages if that. I'll review it tommorow and see if it makes more sense then.

Thanks for jogging my memory Adger.

Rermember, a torque converter is a fluid coupling, where a fluid coupling is not always a torque converter.
A fluid coupling doesn't necessarily multiply anything.

[Adger Smith]

That is why a torque converter has a section called a "Pump".. :~)
Most fluid couplings (simple explanation) operate like similar fans blowing air on another.
AH! Weedhopper, what happens when we change the size and pitch of the blades on one of the fans? :~)