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DIY - Turbo oil inlet restrictor


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Well.. I have been having really bad problems with my Holset HY35W blowing oil out of the turbine oil seal..

 

First I checked my crankcase pressure and there was so much pressure, the oil was not draining out of the turbo, so it backed up and went out into the turbo. Typical signs include burning blue smoke once the car is warmed up and the exhuast is burning the oil. FIRST thing to check is the PCV setup. I added one with some good results, just not perfect.

 

 

Rather than spending $15 from ATPturbo or another company and finding the right thread pitch and length and size of the oil inlet, I said screw it and fab up my own.

 

I used the stock banjo bolt that came on the 280ZX turbo's and I am still using the stock oil lines. (12mmx1.5 pitch BTW in BNPT (yes british))

 

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I went ahead and cleaned, wire brushed and de-greased the banjo bolt. I then welded up the opening.

 

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I took a 1/16 (.060) drill bit and drilled through the weld. Tada, my own oil inlet restrictor. I can increase or decrease the size if I choose. (yeh it looks ugly but hell it works)

 

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Now I called Garret and they recommended an inlet size of .035 for their ball bearing turbos. ATPturbo sells a inlet restrictor of .060. Depending on the turbo the size of the inlet will differ. Remember too small, you'll run the turbo dry on oil and damage the seal from oil starvation. Too big you'll blow the seals out from excess pressure. DO YOUR HOMEWORK!

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Ill be finding out tomarrow, its too dark out tonight to drive it around and look for smoke.

 

But im willing to bet it will fix the problem. Alot of DSM and Honda tech forums have alot of info on using a restrictor with the Holset turbos. So I think this is the best route.

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i had a similar problem with my T3 on RB30ET(all factory),no problems until i doubled the boost then smoke +++ on heavy acceleration

turned out i needed a much bigger breather in the rocker cover and getting rid of the PCV valve which was too restrictive,ran a 1/2 pipe into a catch can....voila

you could test the theory easily by leaving off the filler on the rocker cover,taping a thick rag over the top(to stop oil blowing everywhere)and going for a quick run

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http://www.turbophile.com/technical/diy_catch_can.html

 

It really sounds like you need a air/oil seperator. Mine is very similar to the one pictured with the exception of having my vent run to the fenderwell and using two 5/8 lines.One from the valve cover and the other directly from the stock crankcase ventilation line.This will allow any blowby to be sent to the catch can and then returned to the oil pan.

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But im willing to bet it will fix the problem. Alot of DSM and Honda tech forums have alot of info on using a restrictor with the Holset turbos. So I think this is the best route.

 

 

 

I am curious if anyone else running a Holset has experienced problems? I know Honda's typically use restrictors but then those Vtec engines run extremely high oil pressures.

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  • 10 months later...
Guest grigsz
I should probably update this thread...

 

a properly setup PCV system fixed my smoke problem =)

 

What kind of PCV setup did you do ?

Greg

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In a car I did an engine swap and turbo build on, I did something similar, but was replaceable/removable.

 

The fitting was not a banjo bolt, but could be adapted.

I used an AN to NPT fitting in the turbo itself.

I ran a tap into the opening from the "top" (AN end), I don't recall the actual size or thread at this point.

Used a bolt and cut it off at about 3/8" long, so that I ended up with essentially a grub screw (Didn't have any handy, so used what was on hand), drilled a small hole .045" or so, again, it's been a while. Cut a groove accross the end, to use with a flat tip screwdriver. Added some lock tight to the threads, screwed in, and voila, removable, or replacable restrictor. :)

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I just took a 3/8" hose i believe.. and ran it from the crank case breather to a TEE fitting on the intake manifold. (brake booster line was tee'd off)

 

 

I cut the hose in half in one section to "splice" in the stock PCV valve.

 

Crank breather |==========| PCV valve |==========| Intake manifold

 

= hose | worm gear clamp

 

Works great

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I did the same thing 6 months ago. I ran a hose from the PCV tube to a push-lock fitting that was -6. I then have a -6 to 1/4-BSPT adapter that is on the bottom of my N42 manifold.

 

I cut the hose and inserted a PCV.

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  • 1 month later...

I was having issues with oil being pushed through the seals and into the exhaust. I hooked up the PCV valve like this:

 

Crankcase vent ========PCV valve in intake manifold

 

and added the diy weld and drill oil restrictor you described in the first post in this thread. (and broke 4 bits in the process). It stopped the oil from going through the turbo seals, but now its coming through the banjo bolt. ie. pressure is too high before the banjo bolt. I'm using old copper washers so I'm going to try changing them first but if that doesn't work I guess I'll have to add a second resistor before the banjo.

 

Also, what is an appropriate oil pressure? How high is too high?

The upper limit I see for oil pressure is approximately 75-80 psi

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Doesn't this mean that you are pressurizing/boosting your crankcase? Is your valve cover breather also connected to your intake? Seems like the pressurized manifold would force air past the PCV valve into the crankcase. I must be missing something.

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