Oil Feed In-Line Reducer

[SD99GST]

So I made a mistake that I think Im paying for now... Here is the "situation"...

My car is now smoking at idle, almost instantly... cant see smoke under boost on freeway or highways but heavy at stops and lights. Valve stem seals have recently been replaced and the car drives and feels fine. Boosts normal, pulls strong.

A few months ago I changed my turbo and got a braided oil feed line and appropriate fittings... or so I thought. After installing the turbo I realized that the fitting going to the oil filter housing was not the correct adapter to the steel braided line. The reason is it had what to me looks like a reducer. Long story short, needed to get my car out of my friends garage, really late so reducer was removed and braided line went from turbo straight to oil filter housing. I read a lot about this location needing a reducer so I figure now that Im trying to figure out my problem and fix issues I would start here just in case my turbo seals went bad.

My question:

What exact oil reducer fitting do I need for my Big 16g?

 

[TSIfreek]

You shouldnt need a restrictor for that turbo. Personally I have run for years like that with no problems.

 

[unisonicz]

I have no reducer/restrictor on my b16g and it is coming off of the ofh.

 

[SD99GST]

TSIfreak - But don't you have a 1g? I thought you ran from the head and that was safer than the OFH from what i read. But that's interesting... I thought the OFH had a excessive amount of pressure and was definitely needed.

 

[JusMX141]

Buy a factory 1G oil supply line from the head and be done with it. This is what Curt Brown used on the 499awhp / 10.33 Evo III 16G setup he ran a few years ago; I can't see how anyone's 16G could ever need more oil than what his turbo needed.

Even the factory 1G line from the head has a restrictor built into the banjo end at the turbo.

At head:

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At turbo:

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If I were you I'd ask myself why feeding a 16G unrestricted from the filter housing with roughly three times the pressure and volume that the turbo requires is the right thing to do.

 

[SD99GST]

Buy a factory 1G oil supply line from the head and be done with it. This is what Curt Brown used on the 499awhp / 10.33 Evo III 16G setup he ran a few years ago; I can't see how anyone's 16G could ever need more oil than what his turbo needed.

Even the factory 1G line from the head has a restrictor built into the banjo end at the turbo.

At head:

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At turbo:

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If I were you I'd ask myself why feeding a 16G unrestricted from the filter housing with roughly three times the pressure and volume that the turbo requires is the right thing to do.

Thanks for the input... Didnt really ask myself that question seeing as how the factory T25 was using this location for its feed. Im also under the impression that seeing as how I have a 7bolt head I cant just grab my feed from there... am I wrong? Also if I wanted to use a braided line what reducer would be equivalent to that 1g line...

 

[TSIfreek]

TSIfreak - But don't you have a 1g? I thought you ran from the head and that was safer than the OFH from what i read. But that's interesting... I thought the OFH had a excessive amount of pressure and was definitely needed.

I ran if from the OFH years ago with a -4 line and had no problems with oil pushing past the seals as this was from my first motor that I put 25,000 miles on.
I am now running it off the head but running it off the OFH with a -3 feed line as your restictor is fine.
Many kits come with -4 line that puts alot more oil pressure to the turbo but I didnt have a problem with mine.
I plan on running a -3 line off the OFH but its from the head with a -4 now ..

 

[JusMX141]

Didnt really ask myself that question seeing as how the factory T25 was using this location for its feed.

Two completely different turbos made by two completely different manufacturers with two completely different oiling requirements.

Im also under the impression that seeing as how I have a 7bolt head I cant just grab my feed from there... am I wrong?

All heads are interchangeable, and all of them have the threaded hole in the corner of the head for an oil source.

 

[SD99GST]

Two completely different turbos made by two completely different manufacturers with two completely different oiling requirements.

All heads are interchangeable, and all of them have the threaded hole in the corner of the head for an oil source.

Thanks a lot for the help... Im going to switch feed sources and see how that works out.

 

[JusMX141]

If the turbo is already smoking, the damage may be done. Once oil passes between the turbine seal and the housing, the oil will burn and stick to the seal and housing, causing a poor sealing surface.

Changing the oil feed location after the turbo has started burning oil is like changing the oil pump after your engine blows.

 

[kawgomoo]

your turbo is already wiped out.

You better rebuild it before the wheel touches the housing and the whole thing is trash.

Plain Bearing Turbos Never really require a restrictor. Esp if the oil return line is proper. I always use a -10.

Any resistance in the oil return will cause oil to back up in the turbo and push out the seals.

If you have a ball bearing turbo too much oil pressure "floats" the balls in the bearings and prevents them from turning. This wears flat spots on the balls nearly instantly.

Plain bearing turbos. The shaft rides on a film of oil and never actually touches the bearing. Pressure is required to make this oiling system function.

Too little pressure in a plain bearing makes the shaft push the film of oil out the way and allows the shaft to touch the bearing. This destroys the bearing.

If you have too much oil pressure, the turbo will start to smoke IMMEDIATELY. It wont take days weeks or years for anything to be compromised in the turbo. if it has way too much pressure, or cant drain. you will know it. Quick too.

What you did was starve the turbo, drive it like that and damaged the bearings.

Fortunately rebuild kits are cheap and very easy to install. Make sure to mark your wheel position accurately so you dont have to rebalance it

 

[JusMX141]

Plain Bearing Turbos Never really require a restrictor. Esp if the oil return line is proper.

What's your take on situations where the oil pressure may be too excessive? What method is best to bring the oil pressure entering the turbo to an acceptable level?

Better yet, what's your take on the photos I've posted above which clearly show that the 1G oil feed that comes from the head has an approximately .070" restrictor built into the banjo end at the turbo?

Obviously a restrictor is needed on certain applications.

 

[kawgomoo]

What's your take on situations where the oil pressure may be too excessive? What method is best to bring the oil pressure entering the turbo to an acceptable level?

Better yet, what's your take on the photos I've posted above which clearly show that the 1G oil feed that comes from the head has an approximately .070" restrictor built into the banjo end at the turbo?

Obviously a restrictor is needed on certain applications.

Well...the restrictor is not necessarily there for the sole benefit of the turbo.

Following this holistic view lets start at the top. The valve train spins at half the speed of the crank. The valve train has less friction and therefore less lubrication demands of the bottom end. The oil pump is at the bottom of the engine, closest to the crank and rods. Who have the highest demand for oil pressure and volume.

As oil makes it way to the top of the engine, it is naturally regulated by being bled off, passage size etc. Oil volume to the head is always restricted by the OEM to keep the oil in the pan and not in the valve cover.

This is why oil pressure on the head port is more stable than oil pressure coming right off the filter housing

But i digress. The orifice in the mitsu feed line is calibrated to allow only as much oil as the turbo needs...and no more. In most cases the turbo itself restricts enough flow through bearing tolerance and such. But if for whatever reason the bearings were completely wiped out, and the oil supply to the turbo completely unrestricted...well you could pump the motor dry pretty quick like that!

Im not saying this is the ONLY reason the orifice is there. But to think the size of the hole in the oil feed line relates directly and soley to the needs of the turbo is the kind of "in the box" thinking that will get you in trouble. quickly.


For the record, when i installed my oil line feed kit i recognized this hole and noticed the generic replacement was just a straight through. my solution was simple. I used the upper banjo and AN line supplied with the kit. I cut the lower banjo off the OEM line, welded a -4 fitting to it and called it good.

But still..you arent going to damage a plain bearing turbo from excessive pressure. Worst case, the VOLUME of oil passing through the turbo will swamp the drain line and start to push oil out past the seals. Oil in the exhaust makes smoke and wouldnt pass tailpipe emissions like this. Oil into the compressor can cause a host of issues from gumming the motor up to causing detonation from diluting the intake charge.

My point? Don't look solely at the needs for of turbos bearings...think about the entire system and what the possible outcome of your decision may be. This seems to be a critical decision making process that is missing from most Hobby Tuner's perspective.

 

[JusMX141]

But still..you arent going to damage a plain bearing turbo from excessive pressure.

Actually, I've seen cases where a journal bearing turbo was known to be over-oiled or fed high pressure unrestricted from the filter housing, and the bearings are burned black and the turbine shaft is scored as if it were getting no oil at all.

The theory here is that the oil is being blasted into the tight tolerances of the turbo's journals at such high pressure that the oil is burning and vaporizing instead of lubricating the parts. This theory has been proven on many high-RPM drag racing applications, which is why most V8 drag guys will build their engines with larger oil tolerances in an attempt to aim for oil pressure around 40-60psi at the filter housing wide-open at the end of the track. Some of these cars will idle with pressure as low as 5psi.

 

[SD99GST]

your turbo is already wiped out.

You better rebuild it before the wheel touches the housing and the whole thing is trash.

Plain Bearing Turbos Never really require a restrictor. Esp if the oil return line is proper. I always use a -10.

Any resistance in the oil return will cause oil to back up in the turbo and push out the seals.

If you have a ball bearing turbo too much oil pressure "floats" the balls in the bearings and prevents them from turning. This wears flat spots on the balls nearly instantly.

Plain bearing turbos. The shaft rides on a film of oil and never actually touches the bearing. Pressure is required to make this oiling system function.

Too little pressure in a plain bearing makes the shaft push the film of oil out the way and allows the shaft to touch the bearing. This destroys the bearing.

If you have too much oil pressure, the turbo will start to smoke IMMEDIATELY. It wont take days weeks or years for anything to be compromised in the turbo. if it has way too much pressure, or cant drain. you will know it. Quick too.

What you did was starve the turbo, drive it like that and damaged the bearings.

Fortunately rebuild kits are cheap and very easy to install. Make sure to mark your wheel position accurately so you dont have to rebalance it

Yeah, the turbo will be rebuilt...that's for sure. I just wanted to make sure I get it right the second time around as far as feed goes so that I don't have this issue again. As far as return line goes I'm using a 1g stock return line.

So you said that if the pressure was to be excessive than the turbo would have started passing oil instantly... well in my case this didn't happen, took almost nearly 1.5-2 months for this to actually happen and never was this car ran hard. Is there a test or anything I could do to check if its actually bad seals? Im going to double check my return line and make sure that's on correctly with no damages or anything. Thanks again guys for the help.

The more I read about this whole oil pressure stuff the more confused I get, but i think peoples explanations are starting to come together for me.