JusMX141
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- Dec 13, 2005
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Greensburg,
Pennsylvania
This topic came up a few months ago in a Facebook discussion where I posted a pile of good information so I thought I'd share the info here as well where it can be cataloged and searched. This is only in reference to the "newer" ball bearing Precision turbos which have an air-cooled bearing housing (no coolant ports) made starting in 2012 or so and beyond.
The short answer is "no", and here's why.
Back in the day, Precision's ball bearing lineup (those with coolant ports on the bearing housing) was entirely Garrett-based and used Garrett parts. So the bearing sleeve was a Garrett GT40-type and had the standard steel/brass/phenolic retainers to keep the balls separated. On all of the ball bearing Precisions which have the oil-cooled bearing housing (without coolant ports)...the bearing sleeve is their own design and is *close* to the Garrett but not exact so that Garrett parts cannot be used. While likely being a way to dance around copyright laws, this also allows them to keep only one type of shaft for both journal bearing and ball bearing turbos without the "step" in the shaft that a ball bearing Garrett typically has to center the inner bearing race.
Now for whatever reason the new bearing system is a full-complement design...meaning there's no bearing retainer- a design that is typically only used in low-speed oil-bath applications like gearboxes. This is great for high-load but without anything to keep the balls from contacting each other they require far more lubrication than a typical ball bearing turbo would in order to keep from seizing the entire sleeve during operation. Precision claims the oiling hole in the cage pin acts as enough of a restrictor that you do not need to double-stack a restrictor in the line as you may with a Garrett GT unit; they also want the turbo to pass more oil to suppress heat in the cartridge due to the lack of coolant ports on the outer bearing housing.
^ Garrett left, Precision right
If you decide to use a restrictor and there happens to be a momentary lapse in lubrication which causes the ball bearings to contact each other at full speed and bind, it's an instant catastrophic failure. There's a 7685 at my shop right now which did exactly that and is junk as a result.
Any ball bearing turbo exhibiting excessive oil leakage with limited use is almost guaranteed to be the fault of the drain...whether it be a physical restriction like a kink, or something you can't see like excessive crankcase pressure from a faulty or insufficient PCV system which is causing the engine to breathe through the turbo.
The short answer is "no", and here's why.
Back in the day, Precision's ball bearing lineup (those with coolant ports on the bearing housing) was entirely Garrett-based and used Garrett parts. So the bearing sleeve was a Garrett GT40-type and had the standard steel/brass/phenolic retainers to keep the balls separated. On all of the ball bearing Precisions which have the oil-cooled bearing housing (without coolant ports)...the bearing sleeve is their own design and is *close* to the Garrett but not exact so that Garrett parts cannot be used. While likely being a way to dance around copyright laws, this also allows them to keep only one type of shaft for both journal bearing and ball bearing turbos without the "step" in the shaft that a ball bearing Garrett typically has to center the inner bearing race.
Now for whatever reason the new bearing system is a full-complement design...meaning there's no bearing retainer- a design that is typically only used in low-speed oil-bath applications like gearboxes. This is great for high-load but without anything to keep the balls from contacting each other they require far more lubrication than a typical ball bearing turbo would in order to keep from seizing the entire sleeve during operation. Precision claims the oiling hole in the cage pin acts as enough of a restrictor that you do not need to double-stack a restrictor in the line as you may with a Garrett GT unit; they also want the turbo to pass more oil to suppress heat in the cartridge due to the lack of coolant ports on the outer bearing housing.
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^ Garrett left, Precision right
If you decide to use a restrictor and there happens to be a momentary lapse in lubrication which causes the ball bearings to contact each other at full speed and bind, it's an instant catastrophic failure. There's a 7685 at my shop right now which did exactly that and is junk as a result.
Any ball bearing turbo exhibiting excessive oil leakage with limited use is almost guaranteed to be the fault of the drain...whether it be a physical restriction like a kink, or something you can't see like excessive crankcase pressure from a faulty or insufficient PCV system which is causing the engine to breathe through the turbo.
