Oil pressure low under boost only

[McMsk]

Hi guys,

since a few days I have installed a HKS Sportturbo, Greddy FMIC and an oilfilter relocation kit + oil cooler. For some reason I have noticed, that under bosst, my oil pressure drops. How much oil pressure should I have anyways? where does it measure the oil pressure anyways?

Thanks guys

Mark

 

[jdub]

Take a look at the pic in this thread, 2nd post...it shows where the oil sensor is located on the motor:
http://www.supramania.com/forums/showthread.php?t=16947

When you added the oil relocation kit and oil cooler (I assume a larger one), you also added volume to the system. And that is not a bad thing. You do need to make sure the oil is full (simple things first)...a lot of us actually add a little more oil (.5-1 quart) above the full mark to make sure the oil never gets low. Low oil = rod knock before you know it.

This is a low pressure, high volume system. 10 psi at idle is normal...30-40 psi at highway rpm is normal.

Did you use aftermarket oil lines on the Sport Turbo?

 

[lagged]

Take a look at the pic in this thread, 2nd post...it shows where the oil sensor is located on the motor:
http://www.supramania.com/forums/showthread.php?t=16947

When you added the oil relocation kit and oil cooler (I assume a larger one), you also added volume to the system. And that is not a bad thing. You do need to make sure the oil is full (simple things first)...a lot of us actually add a little more oil (.5-1 quart) above the full mark to make sure the oil never gets low. Low oil = rod knock before you know it.

This is a low pressure, high volume system. 10 psi at idle is normal...30-40 psi at highway rpm is normal.

Did you use aftermarket oil lines on the Sport Turbo?

4psi at idle is normal.

 

[jdub]

4psi at idle is normal.

True...that's the low end. Mines always showed 10 psi at idle before I changed out motors. I did a mod to the oil pump relief valve and get about 10-15 psi at idle (warm) on the new motor.

 

[McMsk]

Well the thing that surprises me, is that when I boost, the pressure drop a bit, and when I cruise at one speed the pressure comes back a bit higher. I at cruising have about 3 bar pressure and when boosting it drops to about 2 or slightly less. Yes I did you a braided steel line on the Turbo. The return line is from the turbo plus a short piece added from the stock turbo. Might i have the wrong oil?

 

[jdub]

Well the thing that surprises me, is that when I boost, the pressure drop a bit, and when I cruise at one speed the pressure comes back a bit higher. I at cruising have about 3 bar pressure and when boosting it drops to about 2 or slightly less. Yes I did you a braided steel line on the Turbo. The return line is from the turbo plus a short piece added from the stock turbo. Might i have the wrong oil?

Hmmm...what size is the braided oil line feeding the turbo? I don't know if too large a line will cause oil pressure to drop, but I do know you can flood the turbo with oil...to the point you blow the turbo oil seals.

Also, the filter you are using may be going into bypass...bad bypass valve in the filter itself.

Did you use the stock oil filter housing with an adapter going to the re-located filter? How about the oil cooler lines...did you use the stock feed from the oil filter housing & return to the oil pan?

JetJock knows a lot about the oil system...perhaps he will chime in here.

 

[McMsk]

The Oil line caem with the Turbo, so I would say it is well dimensioned. I tok the orginal filter mount of the block and now have two big hoses running to the fron, where I have an oilfilter holder with a thermostat. I am just surpirsed, that it drops although the rpm goes up, but f you hold the rpm the pressure comes back? strange or not? Still need to connect my oil temp gauge. Any other reasos possible, bad oil pump? The drain for the stock return line from the oil cooler is closed now.

 

[jdub]

Been thinking about this....

The way the 7M oil system flows (short version) is from the pump to the filter, under pressure some of the oil is diverted to the cooler...the majority is fed to the various oil holes in the block and up to the head. Gravity returns the oil to the pan.

You removed the stock oil filter housing and replaced it with a plate that routes the oil to the remote housing. I'm assuming the oil cooler and associated thermostat is either in the feed or return line to/from the remote oil filter housing. Is this correct?

One of the things I would check first is you don't have a bad filter. Oil filters are cheap...just replace it and top off the motor with oil. I use Wix...the filter bypass valve is integrated at the filter opening. In a Wix, if the filter clogs, oil bypasses the filter completely.

You might also want to check the oil thermostat you installed. It might be restricting oil flow based on temprature...at higher rpm the oil will be hotter and will affect the thermostat. Just remove it completely and see if that solves your problem.

 

[McMsk]

Thanks,

I will have to keep watching this. I will tomorrow go and hook up my oil thermometer and will see what the oil temp is under boost and under normal conditions. As long as the oil pressure doesn't drop too far I guess I will be ok. What would you say is the lowest to run?

Thanks

Mark