Oil cooler -> low oil pressure
03-27-2011, 02:46 PM
Post: #1
Oil cooler -> low oil pressure
My engine looses oil pressure in the oil cooler. With cooler I get 2.5 bar and bypassed I get 5 and a bit. This is my set up:

Stock 20V BT
RX7 oil cooler
mocal sandwich plate
costum hoses

I'll start off inspecting the cooler again and get som bigger hoses. But how big do the hoses need to be?

Sarcasme is just one of the things I offer Wink

Daily driver: '92 Toyota Carina E GTI
Rebuilt project: '86 Levin hatch
[Image: AEU86 AE86 - Oil cooler -> low oil pressure]
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03-27-2011, 04:34 PM
Post: #2
Oil cooler -> low oil pressure
What material are you piping? if they go bigger and that why you pressure is getting lower.
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03-27-2011, 08:09 PM
Post: #3
Oil cooler -> low oil pressure
They are regular hydrolic hoses. I don't know if they are the reason for the decrease in pressure thats why I asked what size is ok Smile

Sarcasme is just one of the things I offer Wink

Daily driver: '92 Toyota Carina E GTI
Rebuilt project: '86 Levin hatch
[Image: AEU86 AE86 - Oil cooler -> low oil pressure]
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03-27-2011, 10:48 PM
Post: #4
Oil cooler -> low oil pressure
First of all:
VVT + oil cooler = bad idea !
(the VVT work with oil pressure)

Also, bigger hose = less pressure (Pressure = Force / Area)
If you want to get more pressure, you have to increase the spring rate of the oil pump. (by adding a washer under the spring)
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03-28-2011, 01:26 AM
Post: #5
Oil cooler -> low oil pressure
Jan, I'm running -8 AN lines for my cooler, I've never noticed a drop in pressure. I'm running the Mocal, a curved cooler, and the -8

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Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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03-28-2011, 01:52 AM
Post: #6
Oil cooler -> low oil pressure
Project D Wrote:Also, bigger hose = less pressure (Pressure = Force / Area)

The force exerted on a piston (for example) is pressure x area. But in a
hydraulic circuit, the pressure is equal throughout the system (neglecting
pressure drop due to restrictions). Therefore the size of the hose only
affects the pressure drop due to friction, and in this respect, a larger
diameter hose is better than a small diameter hose.

For those who care, pressure drop in the hoses is proportional to :-
Velocity squared / diameter Tongue

Cheers... jondee86
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03-28-2011, 05:56 AM
Post: #7
Oil cooler -> low oil pressure
If it was only showing lower pressure at high RPM, like the rise in pressure was not going up in proportion to the rise in RPM, then with no other restriction/s, the hose size is it.
Have you got the filter & plate plumbed right? The filter's outlet is in its center, the outer ring with all the holes is the input to the filter.

I'd look to an RX7 forum about the cooler, whether its inlet & outlet must be correct, and whether there is a common/known problem with its thermo. valve & restricting flow. Good luck.
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03-28-2011, 07:41 AM
Post: #8
Oil cooler -> low oil pressure
The setup is like this: http://forums.club4ag.com/zerothread?id=77707

My hoses are ~2 mm smaler than your -8 AN, Dan. I think I'll go a size up and see if this helps...

If the systems restricktion is in the cooler setup the engine will get full pressure but limited flow.And I'll messure less pressure after the restricktion. This is how I see it but I'm not a flow engineer Smile

A lot of 20V are running oilcoolers and I would have to, to keep it below 100 degr C.

Sarcasme is just one of the things I offer Wink

Daily driver: '92 Toyota Carina E GTI
Rebuilt project: '86 Levin hatch
[Image: AEU86 AE86 - Oil cooler -> low oil pressure]
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03-28-2011, 10:00 AM
Post: #9
Oil cooler -> low oil pressure
Where is the sensor located?

Andrew
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03-28-2011, 10:32 AM
Post: #10
Oil cooler -> low oil pressure
Stock sensor position.

Sarcasme is just one of the things I offer Wink

Daily driver: '92 Toyota Carina E GTI
Rebuilt project: '86 Levin hatch
[Image: AEU86 AE86 - Oil cooler -> low oil pressure]
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