Oil cooler size question

TdiRacing · 07-20-2008, 07:32 PM

What is too big for an oil cooler? I will be using a front mount oil cooler on my 914/6 with the flow vented out the hood. I am just not sure how big I want to make it. Like the thought of added oil, but not sure if there is an adverse affect of it being too big? Will likely use a fan to draw air in thought the cooler as well, so a smaller on may work as well in that application.

Reason I ask is that I make some oil coolers out of intercoolers for my rally car, but this oil system is quite different and do not want to do something stupid for lack of knowledge.

Edit: Will still retain the engine mounted cooler. asking about an extra cooler.

sww914 · 07-20-2008, 08:08 PM

You should have a thermostat in the front oil cooler circuit. If the oil cooler is too big the thermostat will manage the temperature. The oil cooler, if adequate for summer days in the desert will be too big for fall days in the north.

TdiRacing · 07-20-2008, 08:14 PM

Quote:

Originally Posted by sww914

You should have a thermostat in the front oil cooler circuit. If the oil cooler is too big the thermostat will manage the temperature. The oil cooler, if adequate for summer days in the desert will be too big for fall days in the north.

That is what a cover is for

I run large coolers on all my cars and when it gets cold, they get covers put on. I measured what I have and it looks ok I think. Not too big. May just use it.

Eagledriver · 07-21-2008, 10:00 PM

From the looks of it, that cooler should be just right.

-Andy

Walt Fricke · 07-22-2008, 06:35 PM

TDI

From your name, I gather this is a track car. So running in the cold is not so much an issue, and like you, I keep cardboard handy for chilly mornings. A decent opinion requires dimensions, like htxwidthxdepth of finned area. Still, I agree with you and others that this looks big enough for a 2.4. When I was running a short stroke 2.5 (66x88), I ran something that looked about like this in conjunction with the stock cooler on the engine. A Harrison, as I recall. Worked fine.

With air flow in the front valance area and up and out through the hood, you will get really good track flow. I run two 964 coolers on my 2.7 911 track car in that sort of setup. And no engine cooler.

I don't think a fan will do much good, though. Standard wisdom is that cooler fans only really work for idling engines, as in stuck in traffic. I've never had my engine overheat while idling on the grid or otherwise. With a 4 gallon tank, lots of hose, and two sizeable coolers, it seems the modest heat of idling gets carried away. So if you have air ducted through coolers, why bother with fans?

Walt Fricke

TdiRacing · 07-22-2008, 08:03 PM

Yeah I would like to keep the ducting to a minimum as well, so fans will likely not be used. I agree, given the lines and coolers, there is a lot of oil out there and should be controllable.

Yes, I race VW Diesels, and we only have about 5 qt's of oil, so it get super hot in no time. But never had an issues with the TDI engines. I have one with 250K miles on it stock long block still.

The 911 engine seems to be a whole different animal, and I am having a hard time with some of the stuff that people are so concerned about. Still relearning a lot of things. Thanks for everyone's help.

I will measure the cooler and post the dimensions.

Bill Verburg · Bill Verburg's Garage

As long as you run a t-stat it's hard to get too much cooling given the space restraints. Mounting in the clean air supplied in the front lets you get away w/ a smaller cooler.

The amount of air & fuel that go through the enfgine is the final determinant though, a bigger engine that revs higher needs more cooling.

I've had great luck w/ B&B coolers in the valance used w/ 3.6 & 3.8 liter motors(no engine mounted cooler)

B&B sizes are
5.5x2.25x24
5.5x2.25x20
5.5x2.25x15
6.0x3.00x24

size to the valance opening, you can use duct tape to close of parts if necessary

TdiRacing · 07-23-2008, 04:37 PM

Yes, i know the ducting is the most important. Ideally i would like the opening smaller and expand open in front of the cooler, so the air gets trapped and is forced through the cooler, instead of off and around it. This would entail moving the cooler back away from the front of the chassis. Not sure how to design it so I can still put a few things up front in the trunk area. Will have to look at that aspect again.