IRONMAN

What size cooler should I run to cool a Borg Warner 72C. I currently have a 2" by 9" standard cooler and want to upgrade to either 2" X 16" or 3" X 16" The standard one worked fine behind the 500hp motor, I have added some hp so it is too warm now at high speeds.
Thanks

Mbam

We specify a 2x9" bundle minimum, that makes the cooler about 13" overall. The heat load of the transmission is not related to horespower, just RPM. What kind of temp are you seeing?

IRONMAN

It is the 13" overall so I may just add another one in series. or go to the 16". I am not sure on the temp, the gage is a red yellow green range thing, I will have to put a real one on it to monitor it
Thanks

IRONMAN

Marc, I found that the shift cable adjustment was not allowing the transmission lever to go fully to forward so is it possible that was limiting the fluid from getting full flow to the cooler and therefore causing elevated temps?
Thanks, Chris

Mbam

It wouldn't do that but might cause the forward clutches to fail.

How many RPM are you turning it?

IRONMAN

WOT is about 5200. I have added a second 9" bundle cooler in parallel with the first one for oil flow, and in series with the raw water. I have changed the oil to Mobil 1 synthetic ATF that meets the BW requirement of Detroit Diesel Allison C4, Is that a good fluid to use in the BW transmission? Thanks

MILD THUNDER

iTrader: (3)

I've been running type F off the shelf oil in my Borg Warner's for years without issues. I'm unfamiliar with how any of those fancy oils work in the Borg Warner's. I just always stuck with type f as I was told other fluids too slippery can slip the clutches.

A 3x16 cooler would be overkill I think. I'd listen to bam, he is the man when it comes to transmissions!

Marc, can you explain how the rpm comes into play? Like is 800ft lbs harder on the trans at 5000 or 6000 wide open

Mbam

The heat generated in the transmission is due to fluid friction from the drum splashing around in the fluid and from the pump. Until the transmission slips the torque really doesnt matter. So the RPM is the factor here. That is why our drysump version is more effecient, the fluid is way below the drum.

Synthetic fluid in general is not a good idea. We did not test that particular fluid but found a 20% reduction in the torque capacity using anything besides good old type F. The only synthetic we tested that was acceptable was the Amsoil Supershift.

How hot is that transmission actually running? 5200 is normally not a problem with the 9" bundle cooler.