Turbo oil feed restrictor question

[Pete_89T2]

During DGRR, I found out that my new BNR turbo (stage 2) oil smokes when letting off the boost while running hard in the twisties and during the steeper uphill climbs; there's little to no smoke while doing the same over straight, flat & level roads. I'm using a -10 AN plumbing for the turbo oil drain, which follows the stock oil pipe path to the front cover. After discussing the symptoms & my oil drain setup with Bryan at BNR, he suggested I try a 0.060" oil restrictor in the feed line, as close to the turbo oil inlet as possible.

I'm currently using the stock S5 turbo oil feed hardline plumbing which has no restrictor. So I was thinking I can easily fabricate a 0.060" restrictor plate out of some 1/16" thick AL stock that would simply install under the stock pipe flange on the turbo side. Other than needing 2 gaskets to seal up the assembly, does anyone see a downside to this plan?

Only thing I can see is I'd be introducing one more potential point for a leak to occur, and the stock hard lines may need to be bent a bit to make it fit properly. I'm not too concerned with the latter as there appears to be enough tolerance/slack in the stock hardline to accept the extra 1/16" restrictor and gasket on the turbo side.

[RETed]

Before it gets that messy, we should try and confirm that this is the case?

How is your emissions plumbed in right now?
I'm assuming the stock emissions have been removed or modified by now?
I'm talking specifically about the "PCV" system.

As a quick-n-dirty test, remove the oil filler cap and see if the problem changes?
If the smoke disappears, you have too much positive pressure in the "crankcase".

As for your oil return system...
I'm assuming you're using -10 fittings and adapters?
Normally, a -10 line is fine, but it's the more restrictive fittings and adapters that neck the system down that causes a restriction.
As a rule, I try and fit a minimum -12 set-up for any oil return system.
Else, the stock system that uses flanged / "barbed" fittings is usually superior in terms of cross-section area for the oil drain due to this fact...


-Ted

[Pete_89T2]

Originally Posted by RETed

How is your emissions plumbed in right now?
I'm assuming the stock emissions have been removed or modified by now?
I'm talking specifically about the "PCV" system.

As a quick-n-dirty test, remove the oil filler cap and see if the problem changes?
If the smoke disappears, you have too much positive pressure in the "crankcase".

I still have the stock "PCV" plumbed in and fully functional. Did the quick & dirty oil fill cap removal test and there was no major difference.

Originally Posted by RETed

As for your oil return system...
I'm assuming you're using -10 fittings and adapters?
Normally, a -10 line is fine, but it's the more restrictive fittings and adapters that neck the system down that causes a restriction.
As a rule, I try and fit a minimum -12 set-up for any oil return system.
Else, the stock system that uses flanged / "barbed" fittings is usually superior in terms of cross-section area for the oil drain due to this fact...

-Ted

I was concerned about the drainage issue when I built this up, and went out of my way to find AN fittings that are designed with minimal restriction relative to the -10 AN hose ID. The fittings I got do neck down a little, by approx. 1/16" relative to the -10AN hose ID, and couldn't do anything about those, but I was able to drill out the AN male drain flange so its ID matched up to the full -10 AN hose ID. Without boring that fitting out, it would have necked down from like a -10 to like a -8.

[TitaniumTT]

Hey Pete, few options here

As we discussed at DGRR you could weld up the banjo bolt and drill a .060" hole in the banjo bolt.

There are some fittings that you can purchase that allows you to convert the top of the turbo to a -4 fitting and easily allow you to change fitting sizes, you will need to build a new feed line but that is really minimal effort. Hell, Verocious can actually build a line for you when you order parts.

Something like this from Verocious Motorsports - http://www.verociousmotorsports.com/...e-1-8-NPT.html


and couple it with something like this - http://www.verociousmotorsports.com/...r-Fitting.html


that allows you to easily swap out the restrictor size without breaking the gasket seal on top of the turbo. That's probably the most elegant way to go about it. I have seen plenty of people take a soda can, cut it out, and punch a .060" hole in it for a restrictor.... they almost always leak for one reason or another.

I vote the first or second approach. Second is the easiest for swapping different restrictors.

[Pete_89T2]

Originally Posted by TitaniumTT

Hey Pete, few options here

As we discussed at DGRR you could weld up the banjo bolt and drill a .060" hole in the banjo bolt.

I mentioned that idea when I talked to Bryan @ BNR; he said it would work, but for long term durability, he recommended putting the restriction as close to the turbo as possible. Reason is on cold start up, you have a volume of piping to pressurize. While the turbo won't be making any boost at that point, it will start spinning as soon as there is exhaust pressure, and if the restriction is further downstream in the oil line, you'll run a small risk that the turbo can start up a bit dry. That plus I can't weld convinced me I should stick the restriction as close to the turbo as possible.

Originally Posted by TitaniumTT

There are some fittings that you can purchase that allows you to convert the top of the turbo to a -4 fitting and easily allow you to change fitting sizes, you will need to build a new feed line but that is really minimal effort. Hell, Verocious can actually build a line for you when you order parts.

Something like this from Verocious Motorsports - http://www.verociousmotorsports.com/...e-1-8-NPT.html


and couple it with something like this - http://www.verociousmotorsports.com/...r-Fitting.html


that allows you to easily swap out the restrictor size without breaking the gasket seal on top of the turbo. That's probably the most elegant way to go about it. I have seen plenty of people take a soda can, cut it out, and punch a .060" hole in it for a restrictor.... they almost always leak for one reason or another.

I vote the first or second approach. Second is the easiest for swapping different restrictors.

Yup, I've seen the Verocious stuff, and I really like the part with the changable restrictor jets. BUT some of those parts may take at least a few days to get in stock according to Verocious. So I figured the plate option will allow me to do a bit of trial & error testing this weekend at virtually zero cost, other than my time and the extra gaskets I already have on hand. The 1/16" AL bar stock I have isn't quite as flimsy as a soda can, so I don't think it will leak

[TitaniumTT]

Originally Posted by Pete_89T2

I mentioned that idea when I talked to Bryan @ BNR; he said it would work, but for long term durability, he recommended putting the restriction as close to the turbo as possible. Reason is on cold start up, you have a volume of piping to pressurize. While the turbo won't be making any boost at that point, it will start spinning as soon as there is exhaust pressure, and if the restriction is further downstream in the oil line, you'll run a small risk that the turbo can start up a bit dry. That plus I can't weld convinced me I should stick the restriction as close to the turbo as possible.

My bad.... I'm thinking the twins with the banjo right on top of the turbo... sorry.... Bryan's right though.... the restriction in the iron would be a time consuming trip to the turbo.

Originally Posted by Pete_89T2

Yup, I've seen the Verocious stuff, and I really like the part with the changable restrictor jets. BUT some of those parts may take at least a few days to get in stock according to Verocious. So I figured the plate option will allow me to do a bit of trial & error testing this weekend at virtually zero cost, other than my time and the extra gaskets I already have on hand. The 1/16" AL bar stock I have isn't quite as flimsy as a soda can, so I don't think it will leak

Gotcha.... yeah... some .063" AL bar stock should hold up better than a soda can

[Pete_89T2]

Quick update - I went ahead and built up the restrictor plate this past weekend more or less as described. Difference is I used 1/8" thick AL stock and a couple of longer bolts to securely mount it. The thicker restrictor plate still fits fine with the stock oil feed pipe and is leak free. The other difference is since I didn't have a drill bit small enough for the 0.060 hole, I used the smallest bit I had on hand which was 3/32" = 0.09375". Figured for test purposes, I'd rather flow more oil than less.

Anyway, after a test drive, my smoke screen seems to be gone, and the turbo doesn't sound any differently when it spools up & makes boost. Need to get the car into some good twisty roads and steep hills to see if these results are conclusive in high-G situations though, as my test drive was over relatively flat & boring roads.

[RETed]

Isn't this a compressor upgrade on the stock center housing?
Isn't the stock center housing have some kinda built in restrictor?

Anyways, I wanted to comment on the "bigger is better" notion...
Actually, the reality is opposite.
With the kind of engine (oil) pressures we run, it's closer to 100psi or even over.
Smaller is better.
What happens if you go "too big?"
I knew a guy who tried to run a -6 on the oil feed into the turbo - some Garrett T4.
He ended up spinning the front (stat gear) bearing, because too much oil was being diverted from that area - notice the turbo oil feed primarily comes from that area.
So, yes, in this case, more restriction is better than more flow...
As a rule, don't run anything larger than a -4; a -3 is actually better for the turbo oil feed, in this case.


-Ted

[TitaniumTT]

Teds right though, the quick and dirt test is pull the oil fill cap off and I suggest put a sock and a racing fastener incase some oil decides to creep up the neck.

[C. Ludwig]

I've always used these with journal bearing turbos. If you had an unrestricted feed, it's no wonder you had issues.

http://www.atpturbo.com/mm5/merchant...Category_Code=