[Mk2] [Turbo] Where to get an 0.8mm oil restrictor

[Jonny Hizzle]

Anyone point me in the right direction to get an 0.8mm oil restrictor bolt in the uk.
Most searches result in the u.s or oz, and the ones i've found over here are 1mm

cheers

[calum4492]

if i was u id give peter gidden a call he didnt recommend me to use 0.8 as its jus abit to restrictive from memory

[Peter Gidden]

if i was u id give peter gidden a call he didnt recommend me to use 0.8 as its jus abit to restrictive from memory

Correct. Garrett used to recommend 0.8mm but a spate of failures due to oil starvation caused them to drop their recommendation.

Both Simon Hicks and Kong here lost GT turbos when less than 3 months old due to oil starvation with 0.8mm restrictors.

Universal Turbos and AET both advised me to drill out to 2mm.

Since then, i have only stocked 2mm restrictors.

PM me if you want one.

[Chris]

Never used oil restrictors in any of the cars I had involvement in building, or my own.

Not needed.

Chris.

[Jonny Hizzle]

Thanks for the info guys
Read a few stories about guys blowing seals on their ball bearing turbos due to not running restrictors so thought i'd enquire.
I've got a 1.2mm here so i'll drill that out to a 2mm.

[ashley]

Pretty sure I'm running without a restrictor on my GT3076, might need to think about that

[Peter Gidden]

Pretty sure I'm running without a restrictor on my GT3076, might need to think about that

I'll check for you.

[ashley]

[Jonny Hizzle]

GT3076r is what i'm fitting

[bobhatton]

Thanks for the info guys
Read a few stories about guys blowing seals on their ball bearing turbos due to not running restrictors so thought i'd enquire.
I've got a 1.2mm here so i'll drill that out to a 2mm.

You cannot "blow seals" on a turbo, they are just a piston ring type seal and let oil past if the oil is unable to drain away fast enough.

[Jonny Hizzle]

Ok maybe not blow as such but too much pressure can damage the seals causing them to weep. My bigger fear woukd be too much pressure affecting the ball bearings or oil starvation from restricting too much.

[ashley]

You cannot "blow seals" on a turbo, they are just a piston ring type seal and let oil past if the oil is unable to drain away fast enough.

What's your take on fitting a restrictor Bob- any real gains to be had? Garret talk about reducing windage in the bearings, and so reducing spool time...not sure I buy it though

[bobhatton]

Oil Supply & Drainage

Journal Bearing Turbo

"Journal-bearings function similarly to rod or crank bearings in an engine - oil pressure is required to keep components separated. An oil restrictor is generally not needed except for oil-pressure-induced leakage. The recommended oil feed for journal bearing turbochargers is -4AN or hose/tubing with an ID of approximately 0.25. Be sure to use an oil filter that meets or exceeds the OEM specifications. "


Ball Bearing Turbo

"An oil restrictor is recommended for optimal performance with ball bearing turbochargers. Oil pressure of 40 - 45 psi at maximum engine speed is recommended to prevent damage to the turbocharger's internals. In order to achieve this pressure, a restrictor with a 0.040' orifice will normally suffice, but you should always verify the oil pressure entering the turbo after the restrictor in insure that the components are functioning properly. Recommended oil feed is -3AN or -4AN line or hose/tubing with a similar ID. As always, use an oil filter that meets or exceeds the OEM specifications. "

"OIL LEAKAGE SHOULD NOT OCCUR ON A PROPERLY FUNCTIONING SYSTEM IF RESTRICTOR IS NOT USED UNLESS THE SYSTEM PRESSURE IS EXCESSIVELY HIGH. "
Oil Drain

In general, the larger the oil drain, the better. However, a -10AN is typically sufficient for proper oil drainage, but try not to have an inner diameter smaller than the drain hole in the housing as this will likely cause the oil to back up in the center housing. Speaking of oil backing up in the center housing, a gravity feed needs to be just that! The oil outlet should follow the direction of gravity +/-35° when installed in the vehicle on level ground. If a gravity feed is not possible, a scavenge pump should be used to insure that oil flows freely away from the center housing.
Avoid:

Undulations in the line or extended lengths parallel to the ground
Draining into oil pan below oil level
Dead heading into a component behind the oil pan
Area behind the oil pan (windage tray window) where oil sling occurs from crankshaft

When installing your turbocharger, insure that the turbocharger axis of rotation is parallel to the level ground within +/- 15°. This means that the oil inlet/outlet should be within 15° of being perpendicular to level ground.




As you can see from above its the max pressure that has to be controlled not the flow, so some form of pressure controller is the best way not just a restictor

[ashley]

Cheers Bob- I read that from their site as well. I guess you could run a pressure relief valve on the feed line to the turbo, with a turbo by-pass line to limit the pressure the turbo ever sees, seems a bit OTT though.

Might have a play and stick a pressure sensor on the oil feed line to see what's what first

[T.F.S.]

First GT turbo was xxxxx in 500 miles due to a restrictor, now run with new center cartridge and no restrictor and has been fine, GT3071R

[ashley]

Yep- I'm pretty sure I'm running with no restrictor at the moment with no apparent issues, but I'm curious to know exactly what oil pressures I'm throwing at the bearings now I've read Garrett's advice