Oil restrictor on GTW3884

[ken666]

Hey guys

I'm fitted new oil feed and drain lines and filter on my GTW3884, after having my sump modified to run a 19mm drain line, I went to screw the oil feed line to the turbo but it has a flange fitting instead of the standard nipple fitting.

The flange that was supplied with the line kit has a 2mm restrictor orifice, should I open this up or leave it as is?

When I bought the turbo I asked if I need to fit a restrictor and was told not to worry about it.

 

However I was going to be running standard oil pressure at the time, but now I have upgraded to 60psi with the oil pump.

 

What do you think?

I'm a bit concerned that I could starve the turbo of oil.

 

[hjtrbo]

This Garret page has the info you need. 

 

Turbo System Optimization - Garrett Motion

[ken666]

Cheers mate, I was doing some more research right now and have learnt a lot about the oiling and pressure requirements for different types of turbos!

It appears that the orifice in the flange may be intentionally left the size it was drilled so that it can be opened up to the necessary size to achieve the required pressure after it..

I was under the impression that the restrictor was used to regulate the volume flow of oil, not to regulate the pressure of the oil.

That's why I thought the drain line had to be upgraded so significantly?

 

 

 

 

[hjtrbo]

Pressure and flow go hand in hand. In the turbo's case it's a function on the oil flow through the turbo bearings themselves.

 

For the orifice to be sized correctly the recommended turbo oil pressure and flow rate are needed. From there you could calculate it (Hard. Differing viscosity / temperature and supply oil pressure) or just do some on car tests at the end of your build. Looks like it would be easy to knock up a cheap nasty spacer plate and tee a remote mounted oil gauge into it.  

 

A good sized drain is common sense. Can't go wrong copying what Ford did, it works. Looks to me yours is on point.

[ken666]

Pressure and flow are always relative, but there's too many variables to consider when upgrading something that depends on the system to survive!

That's why I studied and asked others for advice.

 

I've got a spare flange sitting here, I'll just connect it to a mechanical gauge and follow some formulas that I have found to calibrate it to suit the oil and system.

Obviously I will oil the turbo from a junction from the oil cooler system while making the necessary adjustments.

Thank for your thoughts

Ken

[Puffwagon]

3 minutes ago, hjtrbo said:

In the turbo's case it's a function on the oil flow through the turbo bearings themselves.

 

Info incoming...

 

That's the case with a journal bearing turbo but it's not the case with a ball bearing turbo. A journal bearing relies on oil pressure in a similar manner that bottom end bearings do. It will create pressure in the same manner that a bottom end does, with clearance.

 

A ball bearing turbo oil passage is like chucking a hotdog down a hallway and only needs enough oil to stay wet. You can send oil in there like an absolute mofo and it won't build pressure until the turbo drain is a restriction. Excess oil can and will pass through the seals into the intake and also straight into the turbine housing that causes smoke.

 

In general you don't restrict a journal bearing and you do restrict a ball bearing.

 

Rule of thumb for ball bearing is 40psi through a 1mm hole but more won't hurt, providing the drain is sufficient and the turbo frame is large enough. Something something skun cats, you can do things a bit differently with a ball bearing and they'll be fine, you can't skimp on oil with a journal bearing or you kill it very quickly.

 

Garrett has the info on their website regarding this, I ain't linking nuffin lol.

[ken666]

Nah, it's a ceramic ball bearing core.

Haha, now what you have stated comes back to my original theory.... ok, not to the depth of journal vs ball bearing requirements!

But I didn't need to consider the other.

I've always associated oil restrictors with the purpose of regulating unnecessary flow to solid lifters and camshaft oiling.

 

It's always been the first thing to do on a motor that has excessively large big end or main bearings. (Cleveland V8's), by regulating the flow to the cam and top end you can safely lubricate the bottom end without fitting a high volume pump which would eventually lead to a failure due to the added load on the distributor gear and pump drive...

Thanks for the feedback, thought I learnt something new today...

Only to have it spoiled!

[Puffwagon]

Bringing the -4 turbo feed down to 1mm has the exact effect in the bottom end that you stated. It is fed from the main oil gallery straight after the oil filter that goes to the bottom end. If you restrict the oil feed it helps the main gallery keep pressure and in turn the head also. If you run the turbo feed straight out of the line it'll drop the main pressure. The head is fed after, perhaps obviously.

 

I haven't measured the exact pressure differences but I have studied the block enough to talk about it.

[ken666]

Yeah well that's the last thing I need, cos I already lose some flow/pressure through the little end oiling.

That's why I uprated the pressure to 60psi, I know that it works the pump gears harder, but everything has been upgraded to ensure reliability. 

I will definitely calibrate it by actual pressure at the flange.

[Puffwagon]

Turbo smart sell an oil pressure regulator designed for this purpose. You can then use a 1mm restrictor at the turbo or in some cases the turbo will already have a suitable restrictor installed into the chra.