My oil pressure seems to be extremely low after the restrictor on my setup. I'm wondering what the normal pressure for ball bearing turbos are.

But first, the technical information: I have a 2014 civic si, with a Comp 5862 ball bearing turbo. I have a -3an feed with a 0.018" restrictor (purchased from comp) and I run 10w30 synthetic oil.

I have 2 oil pressure gauges (one before the restrictor to read engine oil pressure, and the second one after the restrictor to read turbo feed pressure). On a cold start, it reads around 60psi of engine oil pressure and 15-20psi of turbo oil pressure. After my engine gets warmed up and the oil thickens, engine idle pressure would be around 20psi and the turbo pressure would read ZERO.

Even when cruising on the freeway with 70+psi of engine oil pressure, the turbo gauge continues to read 0psi, and I was wondering if that's normal... Prior to my gauge install, I rigged it up to my air compressor and verified the accuracy with a digital tire pressure gauge, and found that the gauge reads fairly accurate (+/- 2psi)

If anyone can chime in on this I'd greatly appreciate it.

Thanks,
Mark

 

Ball bearing turbos require very little oil, and don't need the pressure to create a hydrodynamic wedge that journal bearings require. That being said, .018" is very small, and I doubt you'd have an issue opening it up some, but a call to Comp may not be a bad idea for peace of mind.

 

Like mentioned pressure is not so much a factor with ball bearing as your just lubing the bearings, however you should see some pressure to ensure everything is getting lubed properly. Comp recommends -3 for ball bearing with high oil pressure (50psi+) and -4 for ball bearing with low oil pressure (under 35psi). That said, I would go no smaller than .030-.40 oil restrictor on a -3 line for a ball bearing cartridge in general. And your cars oil pressure would be considered on the higher side. 0.18 sounds really small unless you were running a larger -4 line, even then its on the small side. Did you have issue not running a restrictor before with this unit? IMO its safer to start without a restrictor and go down from there. If you haven't run it without I would do that first. If it appears its getting too much oil start with a larger restrictor and then go down. I usually start with .040 for ball bearing and never had to go smaller than .035 and I exclusively use Comp turbos in my kits. And thats with 5w20 oil, with 10w30 I imagine your getting very little oil coming through that restrictor. You could pop the feed line off and run it to a bucket and cold start the car to get an idea of how much oil your actually getting through that thing.

 

My turbo was actually previously a journal bearing, which took a dump after 8k miles. Seems to me the oil seals were blown and it smoked like crazy while idling. That was with a -3an feed with no restrictor. I then sent it back to comp, paid a bit extra and got it rebuilt with a ball bearing cartridge. I spoke with the salesperson and asked them to include the restrictor that they sell (specifically for ball bearing turbos) in my invoice and I was told it was a 0.018" restrictor. My tuner also told me to use a 0.020" or 0.018" restrictor with my setup since he tunes 9th gen civics all the time, and he has never had a problem. Also when I asked him, he said ball bearing turbos need oil flow, not oil pressure. And as far as I know, only jb turbos need pressure to keep the bearing from creating metal to metal contact. I'm going to disconnect the drain line and see how much oil comes out, I feel like it should be fine though, i've driven 150+ miles so far and I feel like if it wasn't enough oil then I would have already ran into problems of some sort.


Thanks for your help guys!
-Mark

 

Its usually a drain problem as to why you had issues originally. Even though the journal bearing needs pressure, once the oil comes out of the journals there is no pressure in the cavity and the seals see no pressure. Inadequate drain size or not properly vented crankcase can cause the drain cavity to overfill and reach the rings. The only thing that will cause the seals to fail, piston rings rather is excessive heat over time from inadequate oil or bad habbits like hot shutdowns. Even then a properly drained turbo wont leak oil even without seals installed as they are just there to keep crap out of the chra not keep oil in.

Comp units have a 1/2npt drain size that's a .84" hole, drain line needs to be -12 or 3/4" hose at least. The common aftermarket -10 drain adaptors and line kits are actually too small and your lucky if you get away with anything that size or smaller.

I have never personally seen less than .030 run on a bb although I don't have much experience in the import world except for a few cars over the years so not sure if its common for that type of application. I can tell you garrett recommends no smaller than .040 period for their bb units as well regardless of application. My car sees 70-80psi at on cold starts and wot so that's the kind of setups I most commonly deal with. A good practice is you want as much oil as you can get away with and a proper drain size.

Careful with that mindset, 150 miles is nothing in the scheme of things. Ceramic ball bearings are pretty low friction and heat so yes you can get away very little lube and cooling for a long time but if oil is inadequate you will most definitely decrease the life of the cartridge even though things seem fine and it may work for years. Had a customer run a .040 on a journal bearing turbo and it lasted almost a year 10k miles before any ill effect were noticed in the form of shaft play and the compressor wheel eating up the housing, bearings and shaft were toast on tear down. From my experience most guys are just extremely lucky or chalk up any issues to normal wear and tear. Comp's triplex ceramic bearing system is extremely impressive and very forgiving, (its also internally restricted already come to think of it...let me find a pic for ya) but would be a shame to assume its all good and then have issues later down the line, your on the right track though monitoring pressure and checking everything out. On a side note if your not running water cooling to it I would highly recommend it. Its rather cheap and easy to setup and the center section runs around 100 degrees cooler with the water lines hooked up. Also don't have to worry about hot shut downs as the water will continue to flow through thermal siphoning and continue to cool the center section even when the car is off and there is no oil. This will also greatly extend the life of the turbo. Good luck!

 

#ad


Here is a cutaway pic of comps 3cbb cartridge you can see a the bottom of the oil feed its already restricted. I can assure you without some pressure you will not get adequate flow through orifices this size, especial with additional restrictors and heavier weight oils. The additional restrictor should not be a go to thing unless you have to have one due to high oil pressure and the drain not keeping up or being adequate.