915 DIY Trans Cooler

[Jnikic]

There are a few existing threads on trans coolers that I’ve learned from in putting together my kit, but I’ve take a slightly different approach and thought I would share my thoughts …

My goal in this project was to extend the intervals between rebuilds on the stock 915 gearbox in my G body car racing in PCA’s 911CUP. Gearbox is stock, save for a Guards LSD; currently using Swepco 210.

While I would have loved to install the complete Wevo kit, I really didn’t want to pull my trans and have to have it machined. After a lot of deliberation, I chose to put a Setrab Series 1 Fan Pack in my rear passenger seat area. In choosing this location over other options, I hope to (1) protect the cooler from impact with debris, and (2) make it more easily serviceable (if necessary).

I’m using a Tilton cooler pump mounted to the seat bulkhead with 1/2” rubber isolators; the isolators’ studs screwed into M6 rivnuts.



Underneath the car, hot oil exits the trans via a Wevo XT-095 bottom cover, through a Radium check valve, up towards a bulkhead fitting mounting into the seat area. The Wevo piece is beautifully machined, and includes a mesh filter to protect the pump from debris. A temperature sensor (requires an M14x1.5 to NPT adapter) will send data to my AIM MXP, which will fire the pump and fan once the fluid reaches 180 degrees.



Hot fluid enters the cooler from the hose attached to the bulkhead fitting, and colder fluid exits the cooler into the top of the Tilton pump. Tilton recommends routing fluid through the cooler first to extend the pump’s life, so I followed their lead. Rotating the pump head to change the direction of flow was super easy; it required loosening four screws and rotating the head 180 degrees. I used Aeroquip Starlite -8AN hose throughout the install, paired with Aeroquip reusable hose ends.




Fluid exits the pump from the bottom and travels to another bulkhead fitting in the rear driver seat area. I used some Vibrant line separators to affix the oil lines to the airjack lines (-6AN) to keep everything tidy.



From the bulkhead, fluid returns into the transmission via the fill plug location. I used Patrick Motorsports’ M22 to -8AN adapter to accept the return hose.



I hope someone finds this helpful!

[stownsen914]

Nice work. A couple questions/comments.
It might be worth confirming that it's OK to have exposed oil system components inside the cockpit. Some racing orgs require an enclosure.
Make sure there is space (an inch or two) under the cooler for air to escape after passing through it. If the air doesn't have a place to go, it won't pass through the cooler in the first place.

[Jnikic]

Thanks - I think I’m okay with the oil lines inside the cockpit.

The cooler itself is mounted on 1” rubber isolators, which gives clearance between the cooler and the seat base for air to flow through the cooler. This Fan Pack is a puller fan, so it only needs enough clearance to be able to pull sufficient volume through that space.

[fanaudical]

I wasn't familiar with the Tilton cooler pumps and so looked them up. They seem to be a positive displacement single diaphragm type pump. From your description it sounds like the pump may be mounted above the fluid level of the transmission and would have the cooler installed on the inlet side of the pump. I couldn't find any data regarding suction lift capability of the pump. You might prototype that arrangement on the bench (including elevation changes) and make sure the pump can lift the trans oil through the feed lines and cooler. Transmission oil is thick and will incur a lot of friction loss which may be greater than the pump can suck.

EDIT - Never mind - I see that you have the pump mounted under the seat (and the cooler is presumably about the same orientation). I thought you may have had that in the rear seat area above the gearbox.

[PeteKz]

Somewhat related question: Has anyone put a filter in line with the oil cooler? Or is the trans oil too thick and the filter would cause too much restriction?

[Matt Monson]

Originally Posted by PeteKz

Somewhat related question: Has anyone put a filter in line with the oil cooler? Or is the trans oil too thick and the filter would cause too much restriction?

Not a problem. A filter is standard on all 997 Cups.

[stownsen914]

I have a filter on my 914/6 cooler setup too. Different pump but same general idea.

[PeteKz]

Thanks.