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914World.com _ 914World Garage _ Oil Line Help?

Posted by: jfrazar Oct 21 2006, 08:22 PM

I used -10 oil lines on my 3.0 914-6 converison. No Press problems but everyone seems to be running. -12 and -16. Did I screw up?

Thanks,

Posted by: john rogers Oct 21 2006, 09:14 PM

The problem with the dash 10 lines is the velocity of the oil is greater than the dash 12 and this causes a reduction of cooling in the cooler since the oil is moving along faster. The ID of dash 10 is 0.625 and dash 12 is 0.75 so the velocity will have to be higher in the smaller dia pipe since the oil is just about incompressible (for our purposes) and the oil pump is positive displacement. So the answer is........maybe, if the oil does not cool as much as you like then get bigger lines. I had to do that when I went from a dry summped stroker 4 to a 2L high revving 6 in the race car. Aaron now has the old lines safely tucked away in his black beauty.

Posted by: jfrazar Oct 22 2006, 09:21 AM

Thank you for the response.

So it is only an oil cooling issue? I was more afraid of a starvation issue. The car has good oil preasure even with the one bad rod. So I should be okay with -10 oil lines even if I add a front oil cooler with -10's as well.

Posted by: bd1308 Oct 22 2006, 09:24 AM

oil TEMP is the concern here...

Posted by: mikez Oct 22 2006, 10:17 AM

On a 3.0....-10 is about the smallest I would go. Depends on the engine, the cooler and driving conditions.

Not like it's a BAD thing....drive it and see....

Posted by: brant Oct 22 2006, 10:28 AM

For the feed line from the bottom of the tank.. a size AN-10 would be too small. most guys run that 2foot piece as AN-16

its a gravity feed and there can be starvation issues on that line
(no pressure to push the oil back into the motor)

brant

Posted by: Cloudbuster Oct 22 2006, 01:19 PM

QUOTE(john rogers @ Oct 21 2006, 08:14 PM)

The problem with the dash 10 lines is the velocity of the oil is greater than the dash 12 and this causes a reduction of cooling in the cooler since the oil is moving along faster.

I understand the velocity difference between -10 versus -12. The greater the cross section, the lower the velocity of the fluid. Since friction is a function of velocity, -12 move more fluid for the same amount of work than -10. However, isn't it be the cross section of the cooler itself that determines the velocity at which fluid flows through it, and not the feed lines?