Front oil cooler: pressure side or not?

[TdiRacing]

I know this has been debated and I have friends who have used each way without issue, but I have the earlier 2.4L oil pump, and am planning on using it unless I can find a good used one to upgrade. I ran a small oil cooler and small lines off the pressure side on the engine before without issue(adapter plate), but so many people say it is the wrong way and it needs to be on the scavenge side using -12 lines.

IS the this the correct way and is -12 the correct size? Will be going up front on my 914/6 project with a custom oil cooler. Want to start gathering the stuff for this. Thanks.

[J P Stein]

Originally Posted by TdiRacing

I know this has been debated and I have friends who have used each way without issue, but I have the earlier 2.4L oil pump, and am planning on using it unless I can find a good used one to upgrade. I ran a small oil cooler and small lines off the pressure side on the engine before without issue(adapter plate), but so many people say it is the wrong way and it needs to be on the scavenge side using -12 lines.

IS the this the correct way and is -12 the correct size? Will be going up front on my 914/6 project with a custom oil cooler. Want to start gathering the stuff for this. Thanks.

The 2.4L engine mounted oil cooler is on the pressure side already. If you want an auxiliary cooler, it goes on the scavenge side. The idea is to put cool oil into the tank.
-12 lines are OK. The aux cooler in the nose is the best way to get airflow thru it.

[TdiRacing]

Sorry, was asking about an Aux cooler up front, not the factory one on engine.

Yes, it will be up front like the 914/GT cars, jjst vented out the hood and not under the car.

Will start getting some fitting and lines together so I have them when my engine is done in a few months.

[cgarr]

I have 12's off my stock lines going to my setrab cooler on my 3.4 I get 115 degree oil on the return.

[Henry Schmidt]

Here is the new oil cooler we build for 914-6s. The cooler is a modified Mazda cooler.
It was installed on a 3.0 with 40mm carbs, 9.5 JE pistons and "S" cams. The engine ran at 245 before the cooler and 210 after. Of course that is what the gauge said. True temp is unknown. The oil is pulled from a sandwich plate under the filter.

[TdiRacing]

Originally Posted by Henry Schmidt

Here is the new oil cooler we build for 914-6s. The cooler is a modified Mazda cooler.
It was installed on a 3.0 with 40mm carbs, 9.5 JE pistons and "S" cams. The engine ran at 245 before the cooler and 210 after. Of course that is what the gauge said. True temp is unknown. The oil is pulled from a sandwich plate under the filter.

You are running it off the pressure side? What about if you were to run the lines all the way into the trunk in the front and back? Too far? What size lines to use?

I was using a sandwich plate at the filter just like that, then running the lines to the front of the car and back, but with a cooler that was too small. Have a nice large one I want to install. Thanks for you input.

[Henry Schmidt]

The oil filter is on the scavenge side of the oiling system. The oil comes from the engine, through the cooler, through the filter and into the dry sump tank. Air is then removed from the oil through a series of baffles and allowed to rest awaiting transfer to the inlet side of the oil pump.

[TdiRacing]

That seems very counter intuitive to me. I was under the impression that the filter always uses the high pressure side? Guess I need to do more research on the oil system design. The diagrams are not very clear, especially the 914GT stuff out there. Complicated thermostat and weird fittings. I am just going to run a Mocal (In line)thermostat w/O the bypass option like the OEM one and call it a day. Will run -12 lines on the return side of the system as suggested on most books. Hoping to keep my oil temps about 200F, but will see how it all works in the end I guess.

[Eagledriver]

Your engine already has a cooler on the high pressure side. It's attached to the engine case and cooled by the fan. This is similar to the cooler set-up on the VW air cooled engines. The circuit for the aux oil cooler is on the scavenge circuit. This is driven by a separate pump (same housing but separate). The scavenge pump is even bigger than the "high pressure" side pump. You need to be carefull running without a thermostat and bypass valve. When the engine and oil lines/cooler are cold you can see very high pressures on the scavenge circuit. Enought to blow out the filter sometimes. If you are aware of the potential and keep to low RPMs while the system warms up you can run this way with no problems.

-Andy

[TdiRacing]

Originally Posted by Eagledriver

Your engine already has a cooler on the high pressure side. It's attached to the engine case and cooled by the fan. This is similar to the cooler set-up on the VW air cooled engines. The circuit for the aux oil cooler is on the scavenge circuit. This is driven by a separate pump (same housing but separate). The scavenge pump is even bigger than the "high pressure" side pump. You need to be carefull running without a thermostat and bypass valve. When the engine and oil lines/cooler are cold you can see very high pressures on the scavenge circuit. Enought to blow out the filter sometimes. If you are aware of the potential and keep to low RPMs while the system warms up you can run this way with no problems.

-Andy

I am planning on using the Mocal inline thermostat, which does pass the cold oil before opening to go to the cooler. From what I understand the Factory one has another pressure bypass in case the lines or filter gets clogged, which the Mocal does not. Will do the scavenge side. Makes sense now.