Transaxle oil cooler pumps Options

[pcar916]

How many of you are using gear pumps instead of diaphragm types and what filter element (micron) sizes are you using?

[john rogers]

Well, for various HP ratings, Black Forest in San Diego and their race mechanic and at two other shops used this rule of thumb:

100 to 140 HP just keep the bushings and parts tight.

140 to 220 HP use a cooler and you could get 2 years of racing if you were careful.

220 to 300 HP use a cooler and rebuild at the end of the year for sure or sooner. Note a 915 can be used but over an average of 10 years of racing the total cost is nearly the same.

300 HP and up use a Turbo transmission especially if over 350 HP with a lube system. The 914 Bonneville car that had 850 HP used a Turbo 4 speed and cooler setup and never had transmission issues although it kept spinning out when the NO2 was cut in at 185 MPH or so!

[pcar916]

... 220 to 300 HP use a cooler and rebuild at the end of the year for sure or sooner... 300 HP and up use a Turbo transmission.

Well I'm out of the envelope by those guidelines and should have used a cooler since 1994! But after an upcoming hp upgrade on this 993 engine I do think about an inverted short-bellhousing G-50 since it bolts right up, and suck up the large axle/cv angle and the associated hp loss. But it's SO darned heavy and I have these others lying about that I already own. Regardless, I'll always have a cooler/filter system from this point on.

The 930 box is probably a smarter thing, it's just those four gears, marginal torque and technical tracks that worries me. But I suppose first gear is irrelevant anyway.

Haven't compared the two latter options but this is approaching OT for this thread. I haven't searched for the G-50/930 specific topic. On the cooler topic again...

I'll post pix of my cooler installation when I get it installed just to tidy up a bit.

The Tilton folks like to mount the pump after the cooler to keep the temps down in the pump-motor below 150F. Anyone experience priming problems using that configuration (with a check valve)? I'll be mounting my cooler with the fittings on top to keep the cooler circuit oil from going into the sump while turned off.

Thanks for all the thoughts in this thread! I've changed my design because of them.