Home made transmission cooler
 

I wanted to add a tranny cooler to my race car, but it's a non-cooler transmission... so I decided to put in a more conventional cooler with an electric pump.

I modified a drain plug so I could attach an AN fitting. I also took off the end cap of the transmission and tapped a hole for another fitting (where the stock cooler returns).

Luckily, this car already had the spare tire well removed, so I didn't have to do any of that. I did have to cut two rectangular holes in the blanking plate that was installed... and I had to make some brackets/studs to hold the cooler (RX7 oil cooler) and pump. I thought long and hard about how to get airflow over the cooler, and decided on putting NACA ducts in the side windows and then duct that air over the top of the cooler so it exits under the car. E.g. I'm hoping the air moves from a high pressure area to a low pressure area.

The pump is a gear-driven oil scavenge pump... hopefully it's up to the task.

Then I did a little tin knocking and made up a baffle that will help seal the cooler so the air goes where I want.

Once my baffle was in place, it was time to put air ducts in the trunk - again, these will direct air to the top of the cooler. I think this will still give me enough space in the trunk for my gas cans (a convenient place to put then when I trailer to the track).

And, finally, how it will be with the RX7 oil cooler in place. (I still need to make up the plumbing and finish the wiring.)

I think it'll do the trick!

Looks good.

It appears the pump is above the trans output, any concerns with it loosing its prime?

Tom

Good work Van.

Yes - I'll have a check valve after the fitting on the drain plug.

Looks great, let us know how it works? I assume you will be adding a thermostat?

Yes, I'm going to put a thermostatic switch on the transmission (that's what the green wires hanging down are for). But I'm a little unsure what temp setting to go with... I have a switch now that's 140 degrees...

looks good. i'd be interested in knowing how the RX cooler works with the thicker juice of the transmission oil. are you measuring trans fluid temperature with sensors? i have a factory cooler on my trans that i'd like to get rid of if there were a better option such as this.

what size lines/fittings are you running? the factory cooler cant be more than roughly a -10 or -12

Great pics Van. I am going to install a laminar flow double-pass radiator on the trans to keep the install simple. From experience the viscosity of the gear oil is too high for some of the radiator designs that have thin tube wall.

I'm curious if you got a temperature of the fluid before you did this work so you could see how much it went down? Awesome work.

Top notch work as always

Exciting project.
I was just surfing the web and found a kit for a 911 which might work - I'm sure your's was cheaper.

http://www.patrickmotorsports.com/part/1690/

-10AN


I don't have a temperature record yet... but I'm thinking of getting some of these: http://paperthermometer.com/pages/indust.html#8temp


Yeah, I was looking at that. I probably have $250-$300 into it.

I got the lines hooked up. :)

Next step is to run power to the motor and check for leaks.

Bump... What kind of oil temp are you seeing and how has the pump been standing the heat?

Very nice as usual.

The pump is made for for this type of thing, so heat is no problem.

I don't have a gauge for the oil temp, but I have been using those heat-sensitive strips that record temperature - and I'd say the max temp has been between 160 and 180F.

Sounds about right, I had a temp gauge setup in the oil drain plug and the highest temp I saw was 195. This is on a turbo S trans with the integrated cooling loop. I would think your setup would keep the oil cooler.

Van, Nice looking setup! One comment though... you shouldn't put a check valve on the suction side of a pump. Put it after the pump if you need a check valve. I've used that same kind of pump for oil before; it is a positive displacement pump, so it should self prime just fine with the height difference you have there. If I were you, I'd try it without a check valve first and see how it works (just put a section of clear hose in there so you can see if it's pumping cleanly vs. cavitating.)

Sorry - Digging up an old thread.

Van - How is this working for you? Did you have to add puller fans on the cooler or was the ducting sufficient? Anymore info on temps that you were seeing before and after?

I'm looking at this as well ... one of the guys in our series has a cooler mounted and shrouded through the rear firewall and the air is supplied by a NACA duct in the right rear window.
Any more details Van ?

Going to be a Winter project !

Cheers
Phil

I don't have hard numbers, but using a thermal camera, it's easy to see that the cooler keeps the tranny cooler than a car without it. It might only be 10 or 15 degrees - but every little bit helps. It also has the added advantage of holding more fluid, so, in theory, it should last longer.

I did not add a fan, but just rely on the air flow. I haven't had a way to "test" air flow, but I *think* a bit of air goes over it. Under the car is low pressure, creating some suction, and the NACA ducts will also funnel some air in.

I've been happy with the setup (although, after 3 years, I had R&P failure - but I don't think there's a cause and effect relationship here).

Dear Van..if you want to check airflow, you might want to do a "tuft" test with strips of paper, about 3" long scotch taped to the side of the car. If another car can film it beside you while at speed, you will have a pretty good idea how much scoop height and direction you might want to point it..Might be surprising!
Who knows for sure?

I have a simplified version of this on my race car. I'm using the stock mechanical pump from a turbo s trans to push oil up to the cooler in the spare tire well. I use a naca duct from the right rear window. I have a temperature gauge on the system for the 1st year or so, never saw temps over 195.

Can you post some pictures ?

Cheers
phil

Hey Van - I am going to be doing this to my race car. Basically the same setup. Would you change anything about it now that you have ran it for awhile?

Thanks

It think the only thing I'd change would be possibly an off-the-shelf oil cooler - like something from Mocal, as opposed to trying to adapt the RX7 oil cooler. Other than that, I really like the setup.

Van - on the studs you welded on to mount the pump.... Did you use a spot welder or just a welder? It looks like a traditional welder.

Also - did you go with a Tilton or Mocal pump?

Thanks for doing this and posting up the build! It has been an awesome resource!!!!

I just welded the heads of bolts to the sheet metal with my mig welder. :)

And I use a Tilton pump.