Turbo oil feed restrictor question

[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

[Pete_89T2]

Originally Posted by RETed

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

Negative, the only stock part remaining from my turbo is the turbine housing, and even that was modified (ported waste gate). BNR now uses all new center housings along with the new compressor housing & comp wheel. I also got a new turbine wheel/shaft. According to Bryan, there are no oil restrictors in the turbo, not counting the orifices on the new journal bearings themselves.

Originally Posted by RETed

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

Yup, I'm with you on that. I'm still using the stock hard piping to feed oil right up to the turbo, which by eyeball looks to be somewhere between a -3 & -4 ID size. I added the restriction via a plate under the oil feed flange on the CHRA, using a 0.09375 hole. This is a pretty significant restriction, compared to the stock -3-ish oil feed pipe, but not quite as much as the 0.060 Bryan suggested.

[RETed]

Originally Posted by Pete_89T2

Negative, the only stock part remaining from my turbo is the turbine housing, and even that was modified (ported waste gate). BNR now uses all new center housings along with the new compressor housing & comp wheel. I also got a new turbine wheel/shaft. According to Bryan, there are no oil restrictors in the turbo, not counting the orifices on the new journal bearings themselves.

Crap.
I guess I missed that part of the conversation...

That will do it.
Glad you figured this one out!


-Ted