Oil pressure relief, oil cooler, and accusump interaction Options

[Seabird]

Good morning everyone. I am in the process of upgrading my oil system. This is on my dedicated track 914. The upgrades include remote oil cooler, accusump, and CB Maxi oil pump.

In my research for installing the accusump it seems like there are two places that are recommended, in the cooler return line with a check valve and direct to the block. I did not want to use the sandwich plate adapter so I opted for the block option. Simpler with less seals to fail.

As I looked into the workings of the type IV oil system I found a potential problem with both these locations; the oil relief valve on the front of the engine. VW used this valve to bypass the cooler when the oil is thick. But this also means the cooler is bypassed when the oil pressure is high. Does the use of an oil accumulator negate the oil cooler system by maintaining oil pressure?

While on the straights the pump could potentially make 50-60 psi of oil pressure. (the 30mm pump that was in the engine produces those pressures much of a 20 min session) At those oil pressures the cooler will be bypassed based on what I know of the relief valve (bypassing cooler at 60psi, partially open at 35 psi, and sealed at 12psi). The accusump will also build up to that pressure. When I go to brakes and the revs drop the accusump will start pushing back and keep the pressure up till the differential is corrected. If I am back on to the next straight in that time then the pump starts building the pressure again.

Options:

1. Am I making a mountain out of a mole hill? Leave it alone.

2. Plug that relief valve so it stays closed and let the oil cooler thermostat bypass the oil when its cold. This is a pre 76 case so there is the secondary relief valve by cylinder 1. Might be able just to invert the piston so the bypass grove is below the bypass passages.

3. There is also the high pressure pistons sold by pelican parts and others. Does this just shift the bypass window to a higher pressure range?

I would love to hear people's thoughts on this.

Miguel

[Jetsetsurfshop]

I ran 240-250 in the afternoon sessions. Did an extra cool down lap and got back to 230 before the pits. It was hot out there, wow!
If the sessions were any longer, a front cooler would be the answer.
I see a cool 914 in the background in post #41. (behind the ugly dually)
(IMG:style_emoticons/default/biggrin.gif)

[Seabird]

I ran 240-250 in the afternoon sessions. Did an extra cool down lap and got back to 230 before the pits. It was hot out there, wow!
If the sessions were any longer, a front cooler would be the answer.
I see a cool 914 in the background in post #41. (behind the ugly dually)
(IMG:style_emoticons/default/biggrin.gif)

Yeah (IMG:style_emoticons/default/wink.gif) I picked that one for you.

So you think we could see a heat soaking issue where eventually the cooler can't keep up?

Miguel

[Jetsetsurfshop]

So you think we could see a heat soaking issue where eventually the cooler can't keep up?

Miguel
[/quote]

Don't know. I wonder if the oil temp would of exceeded 250 degrees if there was more time in the session. That might be my operating temperature? Thinking about that Chin event coming up in July. They have that happy hour session. That would be one way to find out.
Here's a blanket question, are we worried about what a 914 engine can put up with or the oil viscosity breakdown?
Shane

[Seabird]

[quote name='Jetsetsurfshop' date='Jun 26 2014, 11:50 AM' post='2054674']
So you think we could see a heat soaking issue where eventually the cooler can't keep up?

Miguel
[/quote]

Don't know. I wonder if the oil temp would of exceeded 250 degrees if there was more time in the session. That might be my operating temperature? Thinking about that Chin event coming up in July. They have that happy hour session. That would be one way to find out.
Here's a blanket question, are we worried about what a 914 engine can put up with or the oil viscosity breakdown?
Shane
[/quote]

I guess we'll find out if there is heat soaking ;D You got that big tank too. You think I could get the full hour in with my 15 gallon?

[ChrisFoley]

You think I could get the full hour in with my 15 gallon?

My 1.8L race car gets about 9 mpg.

[stownsen914]

If you want to calibrate your gauge/sender, take them off the car and test in isolation using boiling water (210 degrees). You'll need a 12 volt power source. Dip the sender into the boiling water and see what the gauge says. It's a pretty easy way to see if your gauge/sender are at least in the ballpark of being correct.

Scott