Tried putting in a .093 nitrous jet as an oil restrictor. Seems to clear up the smoke from the tailpipe, but I still see oil being pushed through the compressor wheel seal. What would you guys recommend stepping down to next?

 

I use 0.050" - on the last couple projects, I've simply welded up the end of the oil feed line fitting that screws into the turbo CH, drilled it with an #55 or #56 (3/64 is also right in the same ballpark, but rare) bit, re-chased the threads, then fired the engine up with the line hanging loose into a bucket to check flow.

 

I screwed a bolt into the oil fitting outlet(3-4 threads) and cut the rest of the bolt off. I then used a bigger drill bit say 1/4" to tapper the bolt opening. Then I used a small drill bit to drill the opening. I think I used a 1/64" and it took care of most of my smoking problems. I noticed at some long stops it would start to smoke so I would rev the motor and the smoking would stop. I wish I would have went alittle smaller on the hole and probley will end up going smaller. Hope this helps.

Justin

 

Wow, you guys are running some small restrictors. I thought I remembered reading that it wasn't a good idea to go below about .035. Yellowsierra, that's the same symptoms I'm having. Sometimes it starts to smoke at idle, but if I rev it up the smoke goes away.

 

I really wouldn't run much smaller than a .050" - if you're still having oil control problems, you've got one of three things going on:

- Excess system oil pressure. What's the idling oil pressure, engine warm?

- Shagged out turbo CHRA seals and bearings (if the bearing is way out of spec, the seal doesn't have a chance in hell.). How's the shaft radial end play?

- Poor drainback plumbing. This isn't an STS kit, right? What size is your drain line? Kinks? Pulled it lately and checked it for clogging, including the engine-side bulkhead fitting / dump?

Your problem lies in there somewhere. You can get away with quite a bit - I've got the drain on my old VNT28 about 30 degrees from vertical, with the oil return (-12 AN XRP, big stuff) coming in below the running oil level on the pan (bike packaging is a beatch) - on cold mornings when the oil's real thick (high idle pressure 80 psi) it smokes just a touch - that's gone once it warms up.

 

Idle with a warm engine is about 45 psi

Bearings are good. I have no noticeable radial play.

Nope, it's a front mount. My oil drain is -10 line, no kinks, all downhill sloping, and drains back into the pan above oil level. I replaced the line recently, so I know there's no clogs in it either. You think it's too small?

 

Your setup sounds fine - I'd go down to an 0.050" restrictor (you'll be fine at 45 PSI).

The oil you're seeing - guessing it's after pulling off the comp inlet tube / air filter - are you running a crank vent into the comp inlet tube?

Sometimes that, or an over-oiled air filter, can sluice oil into the compressor inlet / scroll.

 

It's all over the inlet and inside of the compressor housing, and drained down into the intake tube about a foot or so. When I pulled the compressor housing off and ran the RPM up I could see oil coming out between the compressor wheel and the backing plate that it rests on, so I know there's oil coming through the seals for some reason. My filter is a dry filter - no oil, and I do have a crankcase vent in front of the compressor, but the line is dry.

 

F. Well, everything else being good, you're still simply putting too much oil pressure to the seals.

If it only appears as RPM comes up (and engine oil pressure, by association) as you said, it's likely that it's juuuust a CH too much for the seal - try a smaller restrictor.

You won't be anywhere near starving it at 0.050".

 

I'll try that. Thanks for the help I'll report back once I get the smaller restrictor installed.