Front oil cooler line size?

TdiRacing · 10-07-2010, 05:39 PM

I am trying to get my 914/6 chassis ready while I wait on a few other engine parts and am planning on adding a front oil cooler. The cooler I have has -12 line ends on it and from what I read, this seems to be large enough, but others have used -14. Is the larger diameter necessary? Adds more weight overall when you run from front to back, but if the flow is necessary, it is a no brainer. FYI i have a 4 rib carerra pump for this engine, if that matters for scavenge side? Will be 2.4 S basically when done.

Mark Henry · 10-08-2010, 01:41 PM

The -12 is fine.
There's a guy over on the 914world.com site thats selling the 914 GT hard line kits. Many threads and pic's on front cooler set ups over there as well.

mcfoo · 10-08-2010, 03:22 PM

Don't think there is a -14AN.
Main consideration should be smaller "out" and larger back "in".
So if you use -12 out to the remote cooler then use -16 from the dry sump tank back to the motor.
On my race car I use -16 and -20.
Tom B.

Henry Schmidt · Henry Schmidt's Garage

-12 oil lines are adequate for 2.4 making up to 270hp.

We used a different method for cooling an original 914-6 with a 240 hp 3.0.
We employed a simple sandwich plate, -12 stainless line and a Mazda cooler with a built in thermostat.
The customer wanted to keep the chassis as original as possible, therefore no extra holes. The original deck lid was saved to restore the car to factory original.
The engine never had temperature issues even in California on a hot day.

Mark Henry · 10-08-2010, 07:29 PM

Henry, wouldn't that pre-heat the cooling air?
Interesting set up, I have a RX-7 cooler just like that and the ports are smaller size than -12. Did you weld bigger ports onto it?

I'm building a a 3.0 with 9.7 RSR (style) malhe pistons, is that twin plug? Can you share some of the details on the build?

Thanks

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by Mark Henry

Henry, wouldn't that pre-heat the cooling air?

Not enough to matter appearently.

Quote:

Interesting set up, I have a RX-7 cooler just like that and the ports are smaller size than -12. Did you weld bigger ports onto it?

I made special fittings to addapt the AN to metric threads.

Quote:

I'm building a a 3.0 with 9.7 RSR (style) malhe pistons, is that twin plug? Can you share some of the details on the build?

Thanks

It's been 6-7 years since we built that project. I have no idea what the build specs were, sorry.

Walt Fricke · 10-10-2010, 07:24 AM

Agree -12 should be fine both ways. It is roughly the same ID as the stock 911 front cooler lines.

It is when you have a remote sump tank that a larger diameter return line has merit. It is under very little pressue, and may even be negative - you can buy a coil spring insert if collapse becomes an issue. -16 is the most common for that, although -12 worked fine for me until I switched to -16.

TdiRacing · 10-11-2010, 05:02 AM

So the consensus is that -12 or -16 would be the correct size to use on the scavenge side for a front mount cooler? Will use a Mocal thermostat as well, but want to plan ahead and order the correct stuff.

Mark Henry · 10-11-2010, 06:52 AM

-12 is fine, remember when you run to a front cooler the return is not going to the engine... it runs back to the sump tank. Then it goes the short run from the tank to the engine.

Really you should check out 914world.com, massive wealth of 914 knowledge over there.
We don't bite.

TdiRacing · 10-11-2010, 08:13 AM

Am already member there for some time...thanks for the invite. I just wanted to be sure about the 911 oil pump specific size so I do not some how starve the engine of oil or have too much restriction.

J P Stein · 10-11-2010, 06:04 PM

I used -12 on mine. I do like the radiused 90deg fittings when you need one. .....

Walt Fricke · 10-11-2010, 09:22 PM

Great snakes, JP!

The only thing better than using the heater ducting to get oil lines up front and back is to run one on one side of the car, and the other on the other. That way you don't have the outgoing hot oil heating up the returning cooler oil.

Walt

J P Stein · 10-12-2010, 03:36 PM

Walt: there's a couple of congested areas on the 914 for oil line routing.
One is just below the front motor mount and the other is around the pedal cluster.
Both would become involved with the either side routing method so I took the easy way.

Walt Fricke · 10-12-2010, 09:23 PM

Either way, you don't have to worry about someone crushing an oil line with a floor jack.

johnman001 · johnman001's Garage

I used the heater tubes as well. I also opened up the two "conduits" into the front trunk more or less like the GT cars to route the oil lines into the front trunk. There is a small closed box section just to the outside of the pedal cluster on the drivers side and another on the passenger side.

This does introduce hot oil line(s) into the passenger compartment, but they are protected from external dangers and a small cover plate can be used over the oil line to protect your feet.

The GT cars used hard lines in this location.

J P Stein · 10-13-2010, 04:06 PM

Here's a pic (or 2) of mine heading forward.

A gratuitous plug: All this oil system is going on the market soon. The old 2 valve motor (it goes also) just won't cut the mustard vs the 4-500hp monsters in XP. Time to go mutli-cultural mix of Japanses & German. .....