Larger friont mounted oil cooler

[freeridenick]

Question: does hose ID impact oil pressure?

I've picked up an aftermarket oil cooler for a reasonable price, primarily because it came with steel hose and fittings. Now I've got it the hose and adaptors are AN-8 when I expected them to be AN-6. Don't ask me why I didn't ask the seller the question.

AN-8 weld-on adaptors are too large for the engine take-offs so what would be the impact of using these with a a straight AN-6 to AN-8 adaptor?

[KermitLeFrog]

From my pipework designing days I would guess (guess being the operative word) that it would have a negligible effect on the system as a whole.

[E.Marquez]

Question: does hose ID impact oil pressure?

I've picked up an aftermarket oil cooler for a reasonable price, primarily because it came with steel hose and fittings. Now I've got it the hose and adaptors are AN-8 when I expected them to be AN-6. Don't ask me why I didn't ask the seller the question.

AN-8 weld-on adaptors are too large for the engine take-offs so what would be the impact of using these with a a straight AN-6 to AN-8 adaptor?

(Note Im using SAE measurements because the chosen hose and fittings are designed and measured in SAE units)

I used #6 AN which a 3/8" (.375") ID ..the weld on AN fittings had to be enlarged to fit the steel engine fitting tube OD but the stock motor side oil line fitting has an ID of .338" so the #6 AN fitting ID is already larger then the stock line and fittings.

Upping the new fittings and line size to #8 AN with 1/2" (.500") ID As the oil goes from the smaller ID passage to the 1/2" (.500") #8 AN ID hose it will have a small dip in pressure......I doubt you could see it in a gauge if you had one.

NOTE I am NOT a fluid dynamics certified engineer but I did ask one to give me some insight that led me to the opinion above. The formulas and calculations he started spitting out boggled my mind, but in the end, he decided it would make no difference in the application we had. If we had caged the entire oil passage way to 1/2" but made no changes to the pump, then THAT would have made a significant difference, as we keep much of the original oil passages ways at the designed ID size ...IOW a restriction we are not going to see a difference.

[KermitLeFrog]

Non-compressible fluid flow in pipes and fittings is a fascinating subject. Any change in direction or ID gives a pressure drop. I was dealing with water and standard pipes and fittings. All had published coefficients and we were working within quite narrow limits which makes things relatively easy. But once you get into the first principals it becomes very heavy. We used to design very upmarket water features, mainly on cruise liners although we did a fair bit of land based stuff as well. E.g. the largest (at the time) active reflecting pool in the world. https://goo.gl/images/yVaQSP

Great fun.

[freeridenick]

Thanks guys. AN-6 weld on fittings (brazed) to the engine take-off and AN-6 to AN-8 adaptors sounds like the way to go.

I imagine oil volume makes more of a difference to pressure than the size of the lines i.e. if oil level goes below min.

EDIT- doesn't look like I can get An-6 female to AN-8 male adaptors, they all go the other way. So I'd need 6/8 female/female and a 8/8 male/male adaptor. Messy

[KermitLeFrog]

I imagine oil volume makes more of a difference to pressure than the size of the lines i.e. if oil level goes below min.

All the time the oil pump is sucking oil you are good to go, regardless of the actual level.

Most level indicators have a large factor of safety and you need to be well below the min mark before the pump starts sucking air or aerated oil. But, be aware, although tanks and sumps have baffles g forces can still move oil away from the pickup.

Also, don't overfill. It can increase crankcase pressures and pop seals. Just keep it between the marks and you can't go wrong (except when you are meant to check it cold and you check it hot or vice versa).

[E.Marquez]

Thanks guys. AN-6 weld on fittings (brazed) to the engine take-off and AN-6 to AN-8 adaptors sounds like the way to go.

I imagine oil volume makes more of a difference to pressure than the size of the lines i.e. if oil level goes below min.

EDIT- doesn't look like I can get An-6 female to AN-8 male adaptors, they all go the other way. So I'd need 6/8 female/female and a 8/8 male/male adaptor. Messy

If I had to do it with what you have. ...Id either expand the tube on the OEM fitting enough to be able to braze it to the AN 8 fitting (which should not be much..remember the #6 AN weld on fitting has have the ID enlarged to fit the stock fitting tube OD)

Or make a bushing ...braze it to the stock fitting tube, and then that assembly to the #8AN fitting

[8541Hawk]

Question: does hose ID impact oil pressure?

I've picked up an aftermarket oil cooler for a reasonable price, primarily because it came with steel hose and fittings. Now I've got it the hose and adaptors are AN-8 when I expected them to be AN-6. Don't ask me why I didn't ask the seller the question.

AN-8 weld-on adaptors are too large for the engine take-offs so what would be the impact of using these with a a straight AN-6 to AN-8 adaptor?

One thing the appears to be missed while looking at this issue is, yes the pressure will drop when the line goes from -6 to -8 but....
when you get to the other end and go from -8 to -6 the pressure will go back up......so the net result, in this case, would be no real change in oil pressure.

[KermitLeFrog]

Question: does hose ID impact oil pressure?

I've picked up an aftermarket oil cooler for a reasonable price, primarily because it came with steel hose and fittings. Now I've got it the hose and adaptors are AN-8 when I expected them to be AN-6. Don't ask me why I didn't ask the seller the question.

AN-8 weld-on adaptors are too large for the engine take-offs so what would be the impact of using these with a a straight AN-6 to AN-8 adaptor?

One thing the appears to be missed while looking at this issue is, yes the pressure will drop when the line goes from -6 to -8 but....
when you get to the other end and go from -8 to -6 the pressure will go back up......so the net result, in this case, would be no real change in oil pressure.

There will be a pressure drop both from 6 to 8 and from 8 to 6.