Turbo restrictors and filters...

[Supra]

I've had several BOSS550 type housings with two manufacture's center sections, floating bearing, fed by an AN-4, no restrictors & draining to a AN-10. All of these turbos seem to have "smoke upon deceleration" problems within a few hundred miles. I never had a problem prior to A.) switching from a CT-26 based turbo to BOSS + aftermarket and B.) shimming my oil pump during the engine rebuild. I have replaced the feed/drain line with each turbo swap and made sure that the drain is not uphill, level, or kinked. I see 40psi of oil pressure up to 4,500RPM, and ~50-70psi above 4,500RPM. The higher the RPM & boost, the worse the smoking problem gets.

Everything I've read and seen indicates that I need an oil restrictor. I have access to an inline oil filter as well.

Questions:
1.) Does an inline filter do the same job as a restrictor (in terms of restricting, not filtering)? Is one or both prefered?
2.) Once a turbo has started "deceleration smoking", does it have to be rebuilt, or will it clear up?
3.) Assuming one has decent mechanical ability, can it be taken apart by the enduser and be cleaned? Should it be?

 

[Ric]

smoke on decel = bad thrust bearing..

You might want to get a name brand turbo, like ITS, Garrett, etc...

 

[starscream5000]

BOSS turbos from Suprasport.com (not sure if this is the same BOSS as you are talking about) are made by ITS for the record .

 

[Supra]

I've used quality parts from well known vendors. :icon_bigg

I suspect excessive oil pressure in the center section is causing oil to get past the seals. And after damaging and replacing a few turbos, restricting oil flow into the turbo is my next step to troubleshooting. I'm running an AN-4 without restrictor, which doesn't seem right with 50-70psi of oil pressure at times. The BOSS from Suprasport ships with an inline filter, I've been told. I've never had this filter, or a restrictor sooooo if you do the math it seems like I should at least have the filter.

Questions two and three are based on reading Jon@MDC and IJ. posts. IJ. says as long as the oil is pushing out, and not actually coked the shaft/seal, the turbo should clear up after oil burns off. Jon seems to support this when he says the damage is permanent when the seal cokes up and the surface gets scored. Which indicates that the turbo can burn oil for a period of time before permanent damage is done.

 

[Supra]

Nevermind... It appears the restrictor is built into the filter. Google is my friend. :icon_bigg

 

[Fletch124]

Have you talked to the vendors about this? They would be your absolute best bet on knowing.

 

[Ric]

Does your BOV work?

 

[starscream5000]

So the problem being is that you never received the inline filter/restrictor that was suppost to come with it correct?

 

[dbsupra90]

rich-

all the non-bb turbos we sell a -4 feed and -10 drain have been used and have never had a problem. however, none of these cars ran w/ a shimmed pump.

some of the guys run thicker oil and see higher oil pressure levels than stock, but i dont believe they see 70psi. im still not convinced that is a problem tho, a -10 should be more than enough to drain the oil fast enough. perhaps its the orientation of the lines? maybe you could get some pics of what your oil lines look like.

aside from that, oil restrictors just make me nervous. i think i would rather switch to a -3 line than run a restrictor, but thats just me.

 

[Supra]

rich-

all the non-bb turbos we sell a -4 feed and -10 drain have been used and have never had a problem. however, none of these cars ran w/ a shimmed pump.

some of the guys run thicker oil and see higher oil pressure levels than stock, but i dont believe they see 70psi. im still not convinced that is a problem tho, a -10 should be more than enough to drain the oil fast enough. perhaps its the orientation of the lines? maybe you could get some pics of what your oil lines look like.

aside from that, oil restrictors just make me nervous. i think i would rather switch to a -3 line than run a restrictor, but thats just me.

I'm certain oil pressure/volume to the turbo is directly related to the problem. The drain is a Suprasport premade piece and I made certain to bolt it to the block tight, and clocked the turbo center section at an angle to match the drain. There's no kinks, sink traps or BS there.

I'm running 10W30 non-synth oil & WIX filter right now on a tightly built motor. Will be switching to 10W30 Mobil 1 before the car goes out again. I'm hoping the synth will flush out the turbo seal and not coke. Oil pump was shimmed 5.5mm, which is less than others seem to recommend. I still only have 1,500 miles on the motor.

I went for a drive with a friend watching my gauges last night and my oil pressure is a bit higher than I thought. The accurate numbers are: when I start the car cold, it gets 40-50psi at idle and exhaust is mostly clean (could be dumping oil into the cold exhaust pipe). @2,000RPM (max) cold it sees 80psi and smokes a bit. Once it warms up, it gets 20 psi at idle and (what I didn't realize) was at 4,500RPM it's seeing a good 80psi again. I assumed the smoke was boost pressure related... now I know I can make the problem worse by getting into higher RPMs, without changing boost.

We ran around the block 3-4 times under various conditions and then I quit there until I get the restrictor/filter installed. IJ has said he runs +90psi so I'm not too concerned with too high oil pressure in the engine however I'm going to run through the oil cooler setup to ensure that it's functioning correctly. I would have thought that I would loose more oil pressure to the cooler than I am above 40psi. If there is a problem there, my oil pressure should level off significantly lower above 40psi. I cleared the cooler out with simple green & compressed air when the motor was out and replaced all the rubber so i don't see how there could be a blockage problem. Maybe I'll switch to an aftermarket cooler...

And we're supposed to get 3-5 inches of snow tomorrow... Ugh. :3d_frown: On a bright note, I did tear down another R154 and will reassemble it this week. Rebuilding the R154 is actually pretty easy - comparable to rebuilding a short block if you have a press and large bearing puller. It's all about having the right tools and staying organized. And having 5 cores to look at when you forget how it goes together. LOL :icon_bigg

 

[jdub]

Keep in mind Mobil 1 is not a true syn oil...it doesn't do as good a job cleaning out deposits as a PAO or ester based oil. If you're going to go with a Hydrocracked Group III oil (like Mobil 1), Pennzoil Platinum 5W-30 or 10W-30 is a better choice. Pennzoil has taken the formulation of this type oil up a notch...it is very good and superior to the Mobil 1 products IMO.

80 psi is high for a motor with stock bearing clearances...IJ opened up his clearances a bit to compensate for the oil he's using. I does sound like to me you are flooding the turbo bearings...a restrictor should help. Shimming the pump 5.5mm is quite a bit...I did 2mm on mine and it gives me +10 psi over what you would see stock.

Have you considered going to a full-flow cooler set-up controlled by a thermostat (180 deg F)? You would dump the stock filter housing and the pressure valve sending oil to the cooler. You could then use a bit larger full flow filter on a remote filter head. The 7M oil pump pushes the oil through the filter 1st...using a full-flow cooler set-up will allow you to route the oil to the remote filter, to the thermostat/cooler, then back to the motor before it gets to the turbo, bearings and valve train. If you use AN10 hose, that would take care of some of the high pressure and would help keep the oil cooler before it gets to the moving parts. You could also use a dual remote filter head and use a Trasko by-pass filter at the 2nd location...the filter combo would be a excellent filtration system

A simple test for what you have going on now:
Warm the motor up (let the turbo cool down) and remove the feed line to the turbo. Place in a container and run the motor at idle for 30 sec. Measure the volume of oil. Replace the oil feed line and run or pump some oil into the turbo. Replace the oil in the container back to the motor. Do the same thing again, but with the restrictor on the end of the feed hose. This will tell you how much oil is going to the turbo over time at idle...you may be over flowing the drain line back to the block at the oil psi you are running. Might want to find out what the turbo is spec'ed at concerning oil flow 1st

 

[Adjuster]

From everything I've read, the turbo needs a constant supply of oil, but that does not mean it needs more than what the restrictors allow. (Especially if this is a ball bearing turbo, they need less oil as a rule.)

I had a DBB CHRA turbo that would smoke under boost, but only on the uber oil system motor.... Too much volume for the drain is the only thing I could figure.

I have a restrictor in my new setup, but I have not run the car since I started this last round of mods... (I'm being lazy at the moment.)

I bought my restrictor off ebay, section 7 IIRC. (It replaces the oil supply fitting, has the hole and a AN4 male side on it. The hole can be drilled out if more oil flow is needed, but I left it as it arrived with the small hole. I don't have the size, but it's about as big as a #2 pencil lead.)

Should be plenty of oil at the pressures my engine runs at.

 

[Supra]

Keep in mind Mobil 1 is not a true syn oil...it doesn't do as good a job cleaning out deposits as a PAO or ester based oil. If you're going to go with a Hydrocracked Group III oil (like Mobil 1), Pennzoil Platinum 5W-30 or 10W-30 is a better choice. Pennzoil has taken the formulation of this type oil up a notch...it is very good and superior to the Mobil 1 products IMO.

OK, I'll pick up some Pennzoil 5W30 on the way home. The lighter weight oil should help lower the pressure a bit...

80 psi is high for a motor with stock bearing clearances...IJ opened up his clearances a bit to compensate for the oil he's using. I does sound like to me you are flooding the turbo bearings...a restrictor should help. Shimming the pump 5.5mm is quite a bit...I did 2mm on mine and it gives me +10 psi over what you would see stock.

I think a contributor here is that I shimmed a brand new pump. 2mm on a new pump might have been a better idea.

Have you considered going to a full-flow cooler set-up controlled by a thermostat (180 deg F)? You would dump the stock filter housing and the pressure valve sending oil to the cooler. You could then use a bit larger full flow filter on a remote filter head. The 7M oil pump pushes the oil through the filter 1st...using a full-flow cooler set-up will allow you to route the oil to the remote filter, to the thermostat/cooler, then back to the motor before it gets to the turbo, bearings and valve train. If you use AN10 hose, that would take care of some of the high pressure and would help keep the oil cooler before it gets to the moving parts. You could also use a dual remote filter head and use a Trasko by-pass filter at the 2nd location...the filter combo would be a excellent filtration system

I was actually just looking at how much that would cost. It's out of my price range right now to do a cooler + Tstat and all the hoses. I'll need to get what i have working and then upgrade later in the year.

A simple test for what you have going on now:
Warm the motor up (let the turbo cool down) and remove the feed line to the turbo. Place in a container and run the motor at idle for 30 sec. Measure the volume of oil. Replace the oil feed line and run or pump some oil into the turbo. Replace the oil in the container back to the motor. Do the same thing again, but with the restrictor on the end of the feed hose. This will tell you how much oil is going to the turbo over time at idle...you may be over flowing the drain line back to the block at the oil psi you are running. Might want to find out what the turbo is spec'ed at concerning oil flow 1st

How do i know what the Min/Max of oil volume should be? It's not given as a specification, and I assume it would be dependant on the return's ability to flow + foaming + oil type + countless other factors.

I guess my thoughts are that the car is telling me that the center cartridge is flooded and needs the oil restricted, or the pressure lowered. I don't have an easy way to lower the pressure unless there's a genuine problem with the stock oil cooler. Installing a restrictor seemed like the next logical step...

 

[Toy-Rific]

This may help as to one reason you are having blow by of oil through your turbo after you accelerate and than let off. You may need to add a catch can with a large dia hose to your cars system to allow your motor to vent.
On acceleration you will build up internal gases that need to be released and if there is not a suction to pull the pressure from inside than the other easy out is up through your oil return line from the turbo. If this happen than you will be seeing smoke from your turbo when you decelerate.
On another note about your turbo, If you are not running a ball bearing turbo you need that oil to flow in and through the center section for lubrication and cooling. If you limit the flow too much you will hurt the bearings. The oil in the 360deg bearings is to float the shaft so it will not touch the bearing it self, but rather hold it in an oil bath for free spinning. You are better off to allow more oil than less just to try and stop the deceleration smoke.
Greg/Lipp

 

[Supra]

This may help as to one reason you are having blow by of oil through your turbo after you accelerate and than let off. You may need to add a catch can with a large dia hose to your cars system to allow your motor to vent.
On acceleration you will build up internal gases that need to be released and if there is not a suction to pull the pressure from inside than the other easy out is up through your oil return line from the turbo. If this happen than you will be seeing smoke from your turbo when you decelerate.
On another note about your turbo, If you are not running a ball bearing turbo you need that oil to flow in and through the center section for lubrication and cooling. If you limit the flow too much you will hurt the bearings. The oil in the 360deg bearings is to float the shaft so it will not touch the bearing it self, but rather hold it in an oil bath for free spinning. You are better off to allow more oil than less just to try and stop the deceleration smoke.
Greg/Lipp

Greg! I went through the catch can phase with Dr. J and others a few months back. LOL. I have a good catch can with 1/2" hose and it's plumbed pre turbo. Air filter is an 8" K&N brand new.... I have those bases covered.

FYI - The first two turbos were by MDC in a LIPP housing. This turbo is a Masterpower in a LIPP housing. Not DBB. Love the LIPP. :icon_bigg

I looked into aftermarket coolers but that will likely RAISE my oil pressure. I suppose I could do that and see if the smoke goes from bad to oil pouring out the tailpipe!!! LOL Then I'd know where the problem lies. And need a new turbo...

If the problem was just a bit of smoke, I *might* be willing to live with it. But something has killed 2 turbos already, and this 'different' brand turbo is acting exactly the same way as the first w/ a kinked drain line. Only the drain line is new and certainly not kinked. I went through the process of priming the feed line into a coffee filter / cup like Jon @ MDC requested and the feedline pukes a fair amount of oil (no dirt). Can you give me some insight as to how much oil the turbo should have flowing through it? Is there a generic volume or way to calculate it without getting into hard core fluid dynamics and researching foaming oil?

 

[Ric]

^ good information!

 

[Toy-Rific]

My first answer would be, put as much oil in the turbo as you can as long as you have the capacity to get it out. I have found that Mobil One is just too thin for our turbo's and has a way of going through the seals and turning to smoke or into the compressor cover.
I have asked Justin at ITS about how much is too much oil pressure, his answer was, give it 90 psi of you want, the seals will take it as long as there is nothing stopping the oil from getting out and down the return line. If you back the oil up it will go out through the seals.

Greg/Lipp

 

[jdub]

An aftermarket cooler should not raise your pressure...they are usually less restrictive than the stock one. Also, the stock oil filter has a relief valve that functions at 30-40 psi to direct oil to the cooler...after the cooler, the oil is sent directly to the pan. Based on your oil pressure, you will not have a problem with an aftermarket cooler. BTW - a high quality oil will not foam.

In fact, you "could" try this: Remove the relief spring from the oil filter housing and either shorten it or find a weaker spring w/ the same dimensions, or remove some material from the retaining bolt to take some tension off the spring. You will allow more oil to take the cooler circuit back to the pan. Just be careful, you don't want too much diversion.

Greg - Mobil 1 EP 10W-30 is not "too thin"...it has a viscosity of 10.7 cst at 100 deg C. Very close to any other 10W-30 oil out there and is the viscosity the 7M bearings were designed to operate at. IMO he has an oil volume problem...he's over flowing the capacity of the drain line due to the high pump pressure feed.

 

[Supra]

My first answer would be, put as much oil in the turbo as you can as long as you have the capacity to get it out. I have found that Mobil One is just too thin for our turbo's and has a way of going through the seals and turning to smoke or into the compressor cover.
I have asked Justin at ITS about how much is too much oil pressure, his answer was, give it 90 psi of you want, the seals will take it as long as there is nothing stopping the oil from getting out and down the return line. If you back the oil up it will go out through the seals.

Greg/Lipp

Yeah, because it's all about oil volume, not oil pressure. Which is why I don't see how a manufacturer can spec how much oil should be fed, nor how one can reasonably calculate how much oil should go in. On the surface the answer should be, "as much as can flow out the drain". BUT that volume changes when the oil is hot and foamy. So I'm forced to look at what the majority is doing, and they're running a restrictor or less oil pressure.

So, changing the oil to Pennzoil 5W30 (lowering oil pressure), double checking the stock cooler (possibly lowering oil pressure) and/or using a restrictor (lowing oil volume) on a trial and 'hopefully not' error basis seems to be my next option. I'll let you guys know how that pans out. :biglaugh:

 

[jdub]

Rich - the calculation would have to be done with the oil at operating temp (100 deg C)...like I said, the oil should not be foaming The pressure part of the calculation is the unknown here...the turbo oil drain line is larger and will cause a pressure drop. The calculation would have to be done to determine the volume of oil based on the drain tube diameter that would cause excessive pressure in the center section. You would need to know what pressure will overcome the turbo seals. This is the volume of oil the center section can handle.

This is what happens when the oil is restricted from flowing out of the turbo freely...like Greg said, it's an oil bath that is designed to have little pressure in the center section. The volume of oil you are feeding (due to the high pressure output of your pump) to the turbo is exceeding the capacity of the drain line, backing up in the center section, producing pressure there, forcing the oil past the seal.

I would try the restrictor...the 5W-30 is not going to make a big difference.


Edit: A clarification on this - You have two issues going on here...related, but not completely causal.

You have a shimmed pump that is increasing flow through the entire system. Pressure is resistance to flow, but you can also think of it as "rate of flow". For a given amount of time, you are flowing a larger volume of oil through the set size of the oil passages in the motor and the bearings. This only works to a point...one you reach the absolute capacity of the channels/bearings to facilitate flow, pressure will shoot up exponentially. This is what's happening in your motor...your oil pump is working hard because of that resistance to flow.

The problem in the turbo is related, but the oil pump is not causing the pressure problem inside the center housing that is forcing oil past the seal. It is the volume of oil (for a given amount of time) due to the increased flow from the pump. The pressure inside the center housing is caused by the capacity (due to its diameter) of the drain line being exceeded...there is no resistance at the end of the drain where it dumps back into the block.

This is a subtle, but important difference to consider figuring out a solution to your problem.