I had a ultra cool oil cooler installed on my fltrx and i could not put up with the cooler line interfering with changing the oil filter. So i took off the rubber lines and had some braided lines made up and i installed them. My question is, the lines i installed are a smaller diameter than the rubber ones. I test rode it to check for leaks and my oil pressure look the same as before, am i ok with the smaller lines? thanks in advance RC.

 

Where did you have them made? I was thinking the same thing.

 

Same thing as what?

 

Difficult to say for sure without some detailed testing and without the correct test gear you won't be able to do it.

I can offer some pointers for consideration based on fundamental hydraulic principles, which is my area of expertise:

Flow velocity in a line is proportional to the square of the diameter of the bore, i.e small changes in diameter will have a significant effect

Pressure drops in Pipes is complex and depends on whether the flow is laminar or turbulent, so it could easily be proportional to the square of velocity

In other words, pressure drop has a 4th power relationship to diameter, or in simple english, pressure drop rises dramatically with change in diameter

Oil coolers are low pressure devices by their very nature to facilitate effective heat transfer, in other words they don't like being exposed to high pressure and the could blow.

The worst case would be when the oil is at the coldest temp that it flows through the cooler - i.e when the stat opens.

The main risk is the line returning oil from the cooler to the sump, the cooler has no idea how the oil got to it from a flow resistance perspective.

Personally I wouldn't risk it, although I don't want to sound alarmist about it.

If it is the line TO the cooler that is creating the main problem I would consider changing it - if that makes sende

 

I had the lines made at hose and rubber here in salt lake. The fittings are the same size as the oem, the guy who made them said they are no more restrictive because the fittings are the same size.

 

If the lines are too small wouldnt my oil pressure guage show more pressure?

 

Not 100% correct but what he has told you is ok as the run length is not particularely long.

If the fitting diameter is smaller or same size as pipe bore I would be relaxed, but if pipe bore is now smaller than fitting all you have done is shift the bottleneck.

From the sound of things I am guessing you will be fine

 

Thanks sgdiesel, im going to check with hose and rubber tomorrow and make sure they dont have something different. I will tell you this, they sure cleaned up the filter area and look great. sorry i don't have pics.

 

In principle yes, but only if you know exactly what you are looking at.

Firstly the effect will only be noticed when oil is flowing through the cooler, ie the stat has opened that flow path. Can you be sure it was flowing through cooler "before and after"?

Secondly, pressure drop is proportional to viscosity (which changes significantly with temperature). If your "before and after" test was at different temp then the test is not accurate at all. Problem is you probably don't have an oil temp gauge

 

SG you are correct, i do not have a temp guage so i do not know if the bypass opened up and allowed oil through the cooler, I only took it for a 30 min run.