HAILERS

I'd like it if someone can explain to me how the oil seal on the compressor side of a turbo keeps oil from entering the inlet duct. That is all. I THINK I had it explained to me that oil would not enter the inlet duct side of the compressor due to a higher pressure on the turbo side of the compressor wheels side. There's a good chance I wasn't listening when that was explained to me.

The reason I ask, is that this hybrid turbo I have was causing the exaust to belch smoke b/t shifts. It still belched smoke out the tail when I shifted after the install of a large fmic. The belching of smoke quit when I installed a Apexi BOV. No smoke at all now. But if I crank the adjustment screw on the BOV to a higher tension........smoke on each shift. I'm taking saturated intercoolers and inlet ducts. NO oil in the turbine end of the turbo. None at all.

At one point I put the original turbo back on. NO smoke during shifts and the intercooler and inlet duct then had NO oil deposits. It ain't the engine. I took the turbo back to the turbo shop and they took it apart and no damage or worn/ misinstalled parts were found. So I think it has something to do with higher pressure in the inlet duct side of the compressor wheel vs the turbo side of the compressor wheel......when the BOV is not installed and adjusted right.

I have limited knowlede of turbos.....as you can see from above.

RETed

Inlet duct prior to the turbo?
This is next to impossible, unless you're seriously compressor surging the turbo.

Are you using the stock TID?
If so, there's at least one emissions fitting that sucks vapors from the "crankcase" through the fitting.


-Ted

fcfdfan

I know less about turbos than you, Hailers, but having read/re-read your post I find a question mark forming in my mind around the phrase you use, "hybrid turbo." What's hybrid about it? Is the set up a possible contributor to the mystery smoke? Maybe if you describe the turbo itself, you'll get some relevant input from one of the Yodas. Good luck!

HAILERS

Yup. The turbo inlet duct is saturated in oil including the afm. The line with the check valve from the crankcase etc is blocked off. There's no way for oil from the engine to get to entrance of the turbo or turbo inlet duct. It has to be the seal on the compressor during surge, I suppose. I don't need premix or oil injectors with this condition.

It does not do this if I put the original turbo back on.

And I finally figured out it does NOT do this (smoke at each shift), if I have the hybrid installed WITH the Apexi BOV installed and it's set screw set low enough to blow off.

From another post I made a month ago, you might see that I had severe surging in that I could hear the flap on the afm clank when shifting. I could also see the voltage of the afm bang about when shifting. Nothing like my other car with a stock turbo. That's when I decided to buy a aftermarket BOV.

I find that if the BOV is set too strong/tight/high/whatever.......it causes smoke to come out the exaust at each shift.

I run a mere 10psi. Large *** fmic also. It did this also before the fmic. It did it with the stock top mount intercooler.

So do you think that if the surge is high enough it will/might cause the oil inside the turbo's internals to escape out the seal? Or.....is this just not possible/likely?

I need to put a pressure transducer in the turbo inlet duct to see just how high the surge can be.......someday.

OH! Before plugging the crankcase vent line in the turbo inlet duct, I took off the oil filler cap. I installed a pure white sock over the filler pipe. It never turned discolored after driving. No sign of oil on it at all.

HAILERS

It's a stock series five turbo and manifold that was made into a hybrid by machining out the housing and installing a *46* wheel.. Or as stated on the envoice (RX7 HT-18 UPGRADE -46)

fcfdfan

Hailers:

I have the HT-18 hybrid on my 87TII with a stock waste gate mod. I had all kinds of problems with the POS Greddy boost and injector controls installed by those pinheads at Tripoint, but I cannot say I have had any problems with the turbo itself like the one you are describing.

RETed

What kinda air filter are you using?
If you're using a K&N type with a pre-oiled filter media, the oil can sometimes be pulled from the filter media and into the intake tract.


-Ted

HAILERS

Either the K and N or the stock filter.

I used the word saturated. In this case saturated means I could take the top mount intercooler off and turn it on its side and oil would drip out. It was not a film of oil .....it was puddling. After being blown/sucked into the turbo inlet duct it then goes thru the whole baileywick to the throttle body and out the exaust.

In fact it was dripping off the bottom of the area where the turbo inlet duct mates with the turbo. Wet anyway. Drip after accumulating.

It does not seem to do this with the APEXI BOV when its set to its lower tension. I drove it with the lower tension for a week and thought the problem was solved. So out of curiosity I turned the BOV screw to tighten the relief valve. Eeeeek. Billows smoke when shifting during boost. Normal no boost shifts seem ok and without smoke puffs upon shifting.

I think I've found out what I wanted with this post. It seems to be a very rare or exceptional case. It must be the turbo.......even though I took it back to the dealer and saw them take it apart while they showed me how they couldn't see a thing wrong. No shaft play etc and how some small circular metal ring was in place and the gap on it was minimal.

I'm gonna take a spare turbo apart and get in the turvo knowhow field. Ignorance ain't bliss. Or maybe just leave the BOV at the optimum setting where the car does not smoke upon shifting. When its like that the engine boosts normal, the bov does not blow off like a relief valve during boost.......so what am I bitching about...... Thanks for the response. Found out what I wanted to know.

hondahater

iTrader: (2)

nm

HAILERS

Decided to leave the BOV at its optimum (for this car) setting. Shifted at 8200 in third while merging on I20 and have no smoke puffs out the rear. 8200 shifts aren't my normal shifing points. Just a slight misjudgement on my part. I know if I readjust the BOV to a *tighter* setting I'll get the oil in the TID again.

RacerXtreme7

iTrader: (2)

You were seeing surge allowing positive and negative pressure waves to see your compressor. The compressor seal on your hybrid is most likely a dynamic seal (stock uses a carbon seal), were it uses cintifugal forces and boost pressure on the comp side to keep oil from entering the comp side of the turbo. Rx-7's have HIGH oil pressure when compaired to most street vehicles, so when your seeing surge, the low/high pressure is most likely letting oil be pumped into your comp between pressure pulses. NOT GOOD, surge is baaaaddddd for everything. you fixed your surge problems with a proper sized and adjusted blow off valve... be happy and drive the damn thing.

~Mike..............

Wankel7

You have this type of turbo?

MFilippello

iTrader: (2)

I have a 3rd gen and have a similar problem as this. I didn't expect it to be BOV related but after reading this post there are some similarities. I have a gt40r that has plagued me with very sensitive oil problems. Just recently it started smoking a lot after hard pulls and let offs. It wasn't doing this last week and I am searching to see if it is crankcase pressure problem. What struck me is that I did just tighten the stiffness on the BOV before this started.

My question is this. How could compressor surge cause oil to go from the compressor side through all of the intake plumbing and into the engine and out the tail pipe so quickly.? This seems like a long path and the smoke is almost immediate. It would make more sense that the surge is pushing the turbo shaft back and forth allowing oil to also leak out the turbine housing. We may have oil on both sides.

any thoughts,

HAILERS

***********My question is this. How could compressor surge cause oil to go from the compressor side through all of the intake plumbing and into the engine and out the tail pipe so quickly.? This seems like a long path and the smoke is almost immediate. It would make more sense that the surge is pushing the turbo shaft back and forth allowing oil to also leak out the turbine housing. We may have oil on both sides. ********

I am a true believer since I have no purge hose connected to my turbo inlet duct. When the duct was taken off it was saturated with oil and when the intercooler was taken off it dripped with oil if held vertical. In other words there was no other possibility since there is nothing else there except the afm which was wet with oil.

I could hear the afm's flap/vane clank on acceleration/deceleration, and I'm hjalf deaf. The smoke out the exaust during shifts has disappeared altogether after adjusting the bov adjust screw radically outwards. No more clank. No more smoke on shifts. There is still some oil in the turbo inlet though. So a problem still exists to some degree. Radically less than before....but still not 100% right. Makes me wonder how much oil is in trapped in the fmic.

jreynish

iTrader: (2)

If the compressor surge is bad enough you could have caused the seal on the compressor side of the turbo to start leaking the compressor surge could then actually get the turbo to spin backwards pushing air out the inlet forcing the oil into the TID. I hope that answers you question.

IMHO the compressor surge would have to be VERY bad for that to happen.
Check the inward/outward shaft play of you turbo if it moves enough that could indicate the seal is bad if barely at all then I would start searching esle where.