6.5 turbo oil drain question

[2INSANE]

The oil feed inlet hose is a smaller diameter and the outlet oil drain is bigger. I don’t like the design of the oil drain because it is prone to leak. I want to make my own oil drain to keep things cheap.

Does the oil drain have to be bigger then the inlet? Is it ok to use a smaller oil drain the same size as the inlet?

I was thinking about using a wide fuel line bent and flared on the ends with this adapter plate.

https://hosting.photobucket.com/images/m491/chrisjhufstetler/001_IMG_3314.JPG (https://app.photobucket.com/u/chrisjhufstetler/a/60e7626e-0070-4a62-9dd6-2828a7e8a9a9/p/a1887302-5df4-4c48-8782-5deb850c7b0f)

[DmaxMaverick]

Simply, NO! The inlet can be a large as you want, but the drain should always be as large as it can be, reasonably. The inlet is pressurized, but the drain relies on gravity, and MUST be as unrestricted as possible. An obstruction or reduced flow can cause leakage (into the intake) and bearing failure due to reduced heat transfer (oil coking). While the drain line and fittings may be larger than necessary, I have no evidence or data to make that determination. It is a common engineering and design practice in any hydraulic or fluid system that inlet (higher pressure, higher velocity) conduits are smaller than their outlets (lower pressure, lower velocity). You can see this in practice in many systems, including most on your own vehicles in most cases (A/C, coolant, HVAC in general, Power steering, etc.). Bends and radii can also be a factor, in how many bends and their radius, cumulatively. Friction is restriction.

[JohnC]

What he said. There is a ton of oil going through the turbo. If it can't drain out it will end up being burned. The turbo seals are not designed to hold pressure from the oil side out. On a gas engine this just makes it a mosquito fogger. On a Diesel it could cause a run-away. Back in the 70's I and a buddy decided to turbo an Austin Healey 3000. We used a 1/2" drain line. It burned about a quart every 5 miles. We upped the drain to 3/4" and all was good.

Bottom line, you don't want any pressure in the turbo center section.

[2INSANE]

Simply, NO! The inlet can be a large as you want, but the drain should always be as large as it can be, reasonably. The inlet is pressurized, but the drain relies on gravity, and MUST be as unrestricted as possible. An obstruction or reduced flow can cause leakage (into the intake) and bearing failure due to reduced heat transfer (oil coking). While the drain line and fittings may be larger than necessary, I have no evidence or data to make that determination. It is a common engineering and design practice in any hydraulic or fluid system that inlet (higher pressure, higher velocity) conduits are smaller than their outlets (lower pressure, lower velocity). You can see this in practice in many systems, including most on your own vehicles in most cases (A/C, coolant, HVAC in general, Power steering, etc.). Bends and radii can also be a factor, in how many bends and their radius, cumulatively. Friction is restriction.


What he said. There is a ton of oil going through the turbo. If it can't drain out it will end up being burned. The turbo seals are not designed to hold pressure from the oil side out. On a gas engine this just makes it a mosquito fogger. On a Diesel it could cause a run-away. Back in the 70's I and a buddy decided to turbo an Austin Healey 3000. We used a 1/2" drain line. It burned about a quart every 5 miles. We upped the drain to 3/4" and all was good.

Bottom line, you don't want any pressure in the turbo center section.

Ok! Thank you for the quick response!