Ongoing smoke issue
 

Hi guys,

Been absent from the forums for far too long! I’ll dive into the frustrating story that actually kept me away from the rotary community:

I don’t remember exactly how long I’ve been single turbo, but probably at least 8 years. I don’t put very many miles on the car (30,000 in 13 years, with probably 10,000 being the first year). I’m running a closed wastegate BW S366 .91 at 23psi using ID2000s and ID850s. For some reason, and only sometimes, if I boost at full boost, the car will start smoking like crazy. Sometimes it will significantly dissipate if I let it run for some time, sometimes it will go away if I park it for a few weeks. The last time it did it back in 2017, I kind of threw my hands up and just gave up, only starting the car occasionally and moving from garage to garage. This year, I decided to get everything back on track, so I bought a new turbo and had it installed. Car continued to smoke for a little while afterwards, but eventually cleared up completely. Drove for a hundred miles or so easy, then made a SINGLE hard pull. Boom, tons of smoke. I took a look at the turbo, and the guy that swapped my polished compressor cover onto the new turbo didn’t tighten it all the way. I have an adjustable oil pressure restrictor that had been set at 20, so I let the car run for a bit and turned it down to 5. The smoke is starting to mostly clear up, but it’s still more than it should be.

I’m just exhausted with this issue and don’t know how to solve the problem. I was thinking about blocking the oil line to the turbo and putting a rag in the fan to keep it from spinning and seeing if the issue is coming from the engine or the turbo, but I figured I’d give it a shot on here and see if anyone had any ideas of what else I could troubleshoot. I don’t mind spending money on parts, but I don’t want to be replacing a turbo after every pull.

Thank you very much for taking the time to read this, and please excuse my lack of memory on all levels; I’ve been out of the scene for a long time! Just trying to get back to seeing you guys at events!

~Anthony

What are you doing for the PCV system on the car? Catch can or stock setup?

Is the motor relatively healthy? Starts easily, good idle, good compression?

I'm wondering if the smoke is coming from a different source than the turbo. Also, I wouldn't try doing the "stuff a rag" test, that sounds like a really good way to bend compressor blades!

Dale

How big is the oil drain on the turbo and is it routed as vertical as possible?

In the past ive removed the chra from turbine housing and made a block off plate that fits in where the chra goes to eliminate turbo for testing. Then plug oil feed etc. Don't think i have any pictures anymore.

Yep post some details of your feed and drain setup. Whats the manufacturer recommendation for oil restriction?

Could always pull the turbo off of your exhaust manifold to see if it's the engine or the turbo. It will have a lot of oil in the exhaust manifold if it's the engine, and little to none if it's the turbo.

Otherwise, sounds like some solid advice so far with checking for crankcase pressure or an inadequate oil drain on the turbo.

DaleClark: I have a Greddy catch can, just checked it and it has roughly an inch of oil in it. I don’t have access to a rotary compression tester, but the motor idled oddly at lower rpms since it was built; it would hesitate, drop, then jump up and repeat. I have the idle around 1600 right now and it stays steady. I’ll stay away from the rag test, thanks!

Brodie121: I believe it is 10 AN, and it’s not completely vertical; the mechanic at the shop told me there is a slight angle in it that he didn’t like that was causing a slow oil drip before. He said he was able to snug the hose in to prevent it from happening again. After seeing these responses, I’ll get a straight vertical setup.

AE Racer: Not sure what the recommended oil restriction is, I’ll look into that.

Copeland: Only pulled piping off the turbo and it was clean on the cold side, haven’t taken the hot side off yet.

Thank you for the responses!

~Anthony

How is that catch can plumbed in? Is it routing back to the intake manifold or turbo intake?

May also be worth doing a quick pull with the oil cap off to see if it smokes, that could rule out PCV problems.

Dale

You'll never get it perfectly vertical with the way it runs under the front cover to attach, but just make sure its not kinking or drooping down as best you can.
also take a look at the fittings on the oil drain, Some AN adapters have very small internal diameter for no reason.

The catch can is vented to atmosphere. I’ll try it out with the oil cap off tomorrow!




I’ll make sure when I fix that setup to check the diameter. Is 10AN normally what people use?

Is it Bearing or Journal? -10 is usual for bearing, -12 is typical good practice for journal.

Some of those Japanese catch cans are mickey mouse, with little 8~10mm push-on barbs and tiny breathers, which might be ok for stock twins. If using the stock filler neck with that boost to match the can, that might be part of the problem too....a lot of the inline 6 GTRs over here run dual dash 16, at similar boost.

It’s a journal bearing.




Yeah the breather on the catch can isn’t very big. Would it help to weld another one in? And what is the reference to the stock filler neck? Is there an aftermarket one that would let the system breathe easier?




Would these issues being brought up cause the motor to smoke for a substantial long time afterwards?




Sorry for the questions, just trying to take in all of the information.

The can filter breather on the car here went from ~3/4" outlet to 1 1/4" from memory. Smaller size was getting wet from vapor.....and then running down into the engine bay, making a bit of a mess even though the oil quantity was tiny. I'm not sure it would totally apply to you, as it was recycling oil to the engine too via a 1 way valve, rather than just catching. Bigger is undoubtedly better though on these things and same for the can probably.

One of the vendors on here was doing SS oil necks - dual dash 10 outlet? - do know they were made by Linder Power Systems in a batches of around 100......might have been Banzai? Unlikely they'll have any left I'd imagine, as it was a few years ago, so you might have to roll your own.

If nothing else, fixing these items would eliminate them as possible causes of the smoke.

I had been fighting a starts smoking after idling for several minutes when fully warm ( so smoke in traffic) for years now, and it ended up being the engine, after a few sets of twins, then even the 7670EFR was smoking. I temp bolted a header on the car, and ran it and it still smoked.

IRP is making a really nice stainless oil filler neck with AN provisions, that is a current product that they have available.

Dale

Anthony send a picture of your oil feed, return, and catch can routing.

Is there oil in the intercooler piping?

Smoke on decell is often the oil control rings. Could we worn or a porting issue that is causing the motor to ingestt oil.

Is there oil in the exhaust?

As some mentioned above, you could run the car briefly without the turbo to try to isolate where the oil is coming from. You need to be careful and make sure the feed is routed back into the oil neck.


I do still have the IRP stainless baffled oil necks, but do not want to sell you a pretty part unless we are fixing the problem as well. To clear things up, they were designed in conjunction with me by LPS Fab and Nathan Monk. Another company has ripped off the design (missing a key design element in the process) and has claimed it as theirs. https://www.irperformance.com/produc...l-filler-neck/