I will need to buy a new converter when I install a new (700R4) transmission im my car. (I currently have a 10K mile 2500 rpm 12" lockup converter. I won't reuse it because I don't want to take any chances on metal shavings not being completely flushed out of it.)

What I want to know is, what advantage would I have from using a 9.5" lockup converter versus a 12" lockup converter if they are both 2500-2800 rpm units????

Does one take less horsepower to run?
Does one take more abuse?
Does one have a longer life-span behind a 400 ft.lb. engine?
Does one run cooler?
Other than price, for a daily driver, whcih one is best?

:rockon:

 

As you increase the stall speed, eventually you get to a point with a larger converter, where the whole thing has to be built with such big spaces in it, especially between the turbine and the stator, that it will never completely hook up all the way. A smaller converter can be built with less space there, such that when the stall speed is reached, the coupling is closer to 100%.

Also, a smaller one will typically hook up less below the stall speed than a larger one. So you get more of an "on-off" effect, rather than a gradual application of power.

2500-2800 RPM is too low to really use a 9½" effectively. 11" would be better. 9½" ones are appropriate when you want a stall speed above 3200 RPM or so.

 

Thanks!!!!!

 

I hate to disagree with RB83L69 on this one...but here are some other points to consider.

Dana at Pro-built convinced me to get the 9.5" convertor for my combo and the main reason is that the smaller convertor is a lot lighter and will help the trans pump live longer. Also, as for efficiency, the ACT brand 9.5" will go down to 2400 stall.

But to keep in mind here, it depends on the combo. I know that even though my ACT 9.5" 2600 stall is rated at 2600 rpm, the torque of the 406 will actually make that roughly 300-400 rpm higher...

I think that RB's point of view is more in line with the older converter designs...as many other ACT and Vigilante customers will tell you that these designs are pretty smooth...the difference will be at higher rpms...3500 and up...

I would email or call Dana at Pro-built with your combo and see what he recommends...then post back to the board...

 

The 2400 is what I am looking at with my 3.42 gears. That is about the RPM I run at 70 Mph. I don't want it slipping too much...

Thanks for the info!!!! If I can ever get off work at a decent hour I plan on calling Dana for more indepth trans and TC info.....