turbo bearings/seals destroyed WHILE using an oil restrictor?!?!?!

[MarkEmark]

It's a typical scenario for me: dyno appointment is next Thursday, and I notice blueish-white smoke that reeks of oil coming out of my exhaust while I'm at the drive-thru of Dunkin' Donuts.

Immediately I assumed the worst, so I did a compression test: 166 psi across the board, and the car still feels plenty fast, and not low on power compared to when there wasn't any smoke.

Turbo still spools up quickly, sounds great, and hits 15 psi and holds it.

The turbo is a BRAND NEW (NOT refurbished or rebuilt) Garrett T3 super 60 with a .63 a/r turbine, stage III turbine wheel, and a 360 degree thrust bearing. It's been used for about 2000 miles.

For the first 1000 miles while the engine was being broken in, there was no oil-restrictor on the oil feed line. The turbo didn't boost past 8 psi, but there wasn't a single bit of smoke whatsoever for the first 1000 miles while running without a restrictor. When I turned up the boost, I added an oil restrictor, because everyone says it's needed, and that without it, excessive oil pressure to the bearings will cause turbo seal failure. The only other thing I have changed since breaking it in is using a valve-cover breather for the PCV line instead of having it routed to the turbo inlet pipe, which is where it was plumbed before.

The restrictor used is .075" or about 1/13". Most people use 1/16" or .060". The difference in size for the restrictor I used is most surely negligible.

Anyhow, with this restrictor, for about 1000 miles there was no smoke whatsoever. Then all of a sudden one day it starts smoking quite a bit of blueish-white smoke. Had my dad follow me and he said the smoke increased when I got on throttle, but not ALL the time; it also smokes *sometimes* when idling.

So where have I gone wrong? I used an oil restrictor for the sole purpose of PREVENTING turbo seal damage, yet it happened anyway. Brand new $500 turbo. I'm pretty pissed.

The turbo drain-line is not the problem; it's stainless steel hose with aeroquip fittings, the fitting on the pan is plenty high, and I run on the low-side of the dip-stick just to make sure the oil won't back up and cause turbo seal failure.

I know BB turbos need an oil restrictor, and I've heard that sr20det's have a built-in restrictor in the turbo feed line...but many other car manufacturers with turbocharged models do NOT use restrictors (like volvo, saab, etc).

Could it be that the turbo WASN'T getting enough oil, that is, because of the restrictor the flow was prevented enough such that there wasn't a "hydrodnyamic wedge" of oil surrounding the bearing (dad's words)? Doing some research on turbo failure, I found out that it's usually the bearings that fail which cause subsequent seal leakage...the seals don't just "blow". And bearing failure is caused by a LACK of lubrication.

I'm understandably irritated, and sh1t like this is just one more reason I've been contemplating getting rid of the car...it's just a money sink hole.

Any input from the experts? Has anyone else had turbo failure despite using an oil restrictor?!?!

[KATwo40]

Our PCV system is a positive pressure system and requires running the valve cover line to the turbo inlet pipe. The venturi effect creates scavenging. Otherwise, you get excessive crankcase pressure, resulting in some oil smoke and other crap.

Re-route that, then re-test.

On another note, turbo boost pressure has nothing to do with whether or not you need a restrictor.

Cars that don't run restrictors (Volvo, Saab, DSM, etc.) don't have 60psi running through the turbo oil feed line. It's a low pressure outlet from the block where the oil lines connect. There's a big difference.

According to Corky Bell's "Maximum Boost," it's recommend to have no more than around 35psi at the turbine housing oil inlet. Running the restrictor in the line is not going to starve your turbo of oil. I run a 1/16" restrictor and -4an line. No turbo failure on the T3/T04E.

One other point to consider...

When the bearings wear enough to effect the seal, the turbo is pretty much shot. The bearing and wheel tolerances are so close that it doesn't take much shaft play from bearing wear to touch the sides of the housings (the wheels, that is).

If you're seeing the smoke @ idle and you know it's turbo seal leakage, it's the turbine side, which is not even a seal. It's a piston and ring design. Usually this wears as a result of oil coking.

[MarkEmark]

Our PCV system is a positive pressure system and requires running the valve cover line to the turbo inlet pipe. The venturi effect creates scavenging. Otherwise, you get excessive crankcase pressure, resulting in some oil smoke and other crap.

Re-route that, then re-test.

On another note, turbo boost pressure has nothing to do with whether or not you need a restrictor.

Cars that don't run restrictors (Volvo, Saab, DSM, etc.) don't have 60psi running through the turbo oil feed line. It's a low pressure outlet from the block where the oil lines connect. There's a big difference.

According to Corky Bell's "Maximum Boost," it's recommend to have no more than around 35psi at the turbine housing oil inlet. Running the restrictor in the line is not going to starve your turbo of oil. I run a 1/16" restrictor and -4an line. No turbo failure on the T3/T04E.

One other point to consider...

When the bearings wear enough to effect the seal, the turbo is pretty much shot. The bearing and wheel tolerances are so close that it doesn't take much shaft play from bearing wear to touch the sides of the housings (the wheels, that is).

If you're seeing the smoke @ idle and you know it's turbo seal leakage, it's the turbine side, which is not even a seal. It's a piston and ring design. Usually this wears as a result of oil coking.

First, a comment about the PCV...i've had it run both ways and there's been no detectable difference, not to mention, the smoking problem happened well after I had just put a breather on the valve cover line; it wasn't a concurrent problem.

I knew it was the turbo at fault because of the good compression on all cylinders and because it didn't smoke while decelerating under vacuum...There was also no excessive blow-by because there was no oil on the inside of the line from the valve cover.

I realize turbo boost pressure has no bearing on whether or not you need a restrictor; I merely added that point to convey that the turbocharger was otherwise functioning perfectly, and there was no detectable loss in power anywhere.

The smoking was coming from a clogged oil drain line, clogged from a LARGE chunk of coked 5w30 regular oil. When I took the drain line off after the turbo was out of a car a chunk fell out, and then I found a semi-circle chunk of coked oil with the diameter of about a quarter (money), and the thickness of about 5/16". If I had my digital camera, which is in some lucky hands down in the Dominican Republic, I'd take a picture.

The problem now is to figure out WHY the hell the oil coked so badly that it clogged the oil-return line. My street is about 1/4 of a mile, and I am never in boost coming up it after a ride, in fact, for the last mile drive to my house, I'm never in boost. I ALWAYS let the car idle in the driveway while I wait for the garage to open, and then I ALWAYS let the car idle at least 30 seconds in addition to letting it idle on the driveway while it's actually in the garage. In other words, I am very conscientious about making sure the turbo has time to cool down. I am also running a very efficient front-mount oil cooler, which no other KA-T i know of is running (except for AZHitman, who is running my old setup).

Now if I had been using a high-quality synthetic oil, chances are it wouldn't have coked like the regular 5w30 and blocked the drain-line. Only reason I wasn't running synthetic is because, as I've said before, the engine only has 2000 miles on it...it's just been broken in and I wanted to wait for everything to break in before switching to synthetic. Guess I waited a little too long.

Nonetheless, even regular oil should NOT have coked like that so easily and so quickly (this was a LARGE chunk), considering I always let the engine and turbo cool down by idling it. Only other thing I can think of is that the tiny orifice of the restrictor, coupled with the fact that oil-pressure is lowest at idle, didn't let enough oil flow through the turbo while the engine was idling to properly cool the turbo down, causing the oil in the center section to coke. I understand the theory behind using an oil restrictor, but the oil didn't coke in the turbo just from me being an idiot and boosting it real hard and shutting it off suddenly, nor did it come from overly hot oil in the feed-line. The ideal thing (although prohibitively complex) would be to use some kind of needle-valve actuated from the cabin that can bypass the restrictor when the engine is idling and just about to be shut off to assure there's plenty of oil flow; during driving, however, the restrictor would be used. Too bad this couldn't be done very easily.

I should add that I, as well as many other people, have run successfully and for quite some time without an oil-restrictor on the feed-line; my old turbo was on there for about 4000 miles w/o a restrictor and never ONCE did it smoke, and the seals/bearings on it were fine when I removed it.

The car has only been driven about 10 miles since I noticed the smoking problem, so instead of wasting $ and time re-doing the bearings and seals, I'm going to re-install the turbo after I thoroughly flush out the center section area and see if it smokes anymore; now that theres no chunks blocking the drain line, the oil won't need to be forced through the seals. Hopefully the damage isn't 100% irreparable. We'll see though...The shaft-play on the turbo isn't that bad...both wheels spin freely and there's enough clearance between the wheels and the housings.

Right now I'm going to put the turbo back on, switch to synthetic oil, and NOT run an oil-restrictor, and make damn sure I give the engine even MORE time to cool down. If the smoking gets even worse then I'll know it's due to the excessive pressure from not using the restrictor and I'll bite the bullet and re-do the seals and the turbos. However, it's tricky, because now that the seals are ALREADY probably damaged, it could smoke more due to the higher volume and pressure of unrestricted oil flowing through the damaged seals, oil that perhaps would not blow-by the seals if they were undamaged. Again, I ran for quite some time with no problem with an unrestricted feed-line.

Maybe I'll compromise and use a restrictor that's substantially larger than the old one but still smaller than the regular feed line, but there's no way in hell I'm using that tiny .060" one that I bought from ATP a while back. If anyone wants it, it's for sale!

[KATwo40]

Glad you found the root of the problem. This gets me thinking...do I want to drill out my 1/16" restrictor to about 1/8"?

I think your turbo should be fine. You should remember, the turbine side is only sealed via a piston and ring. There's nothing to "blow" out and it should be just fine, unless coking has sanded the ring and piston groove to the point at which it cannot seal properly.

Now I think I'd like to go inspect my lines and CHRA on the ol' T04E...

Thanks for the followup.

[crzycav86]

Man you have some really bad luck. At least you know what the problem is now.

[j-z]

well damn.... i guess 30 seconds with the restrictor wasnt near long enough to help cool the oil. no matter where i drove wiht my lude id always have the hks timer set to 2 minutes for cool down time. i think 3 minutes with a restrictor would be plenty good. thanks for the heads up though as im using a restrictor on my turbo in the 240 this go around. ill def have it cool for 3 minutes atleast if not a lil more to be safe.

[Jookmasta]

first off sorry to hear. secondly, what size is your oil feed line? i personally run a very similar turbo to you and i use a -3AN feed line. no restrictor at all..............and this has been like this for the past 1 year or so that i have been ka-t. the use of an oil restrictor is not needed with a -3AN line............

as for the use of regular oil, i think u are due for an oil change at about 1800 miles when using the regular stuff. i know it should be good 2000 miles with no issues but im just paranoid like that. nonetheless, hopefully the turbo is covered under warranty perhaps? not sure how those things work. good luck with it and hopefully the restrictor was the issue.........

[Nissan_240sx]

that sucks. good luck

[MarkEmark]

IIRC it's a -3.

BTW, cleaned the turbo out today out of all the junk and re-installed it.

Took it out tonight, dad followed me, I got on boost in multiple gears WOT and not a puff of smoke. No smoke at idle either.

Problem solved (no restrictor running this time, and 10w30 mobil 1 synthetic).

The problem was discovered, diagnosed, and fixed in 3 days. Not bad haha.

I'll put a pic up soon of that coked section of oil.

Moral of the story: OIL RESTRICTORS AREN'T NECESSARILY THE BEST THING NOR DO THEY PREVENT TURBO SEALS/BEARINGS FROM GOING, and if you do use one, use a bigger one, or make damn sure you let your car idle for about 3 minutes EVERY time you drive it.

As I said, I'm not going to run any. So far, so good.

[AZhitman]

Good info Mark -

I'm gonna look and see what size mine is this weekend.

[Jookmasta]

hopefully thats in the sticky for the general ka-t knowledge. the main reason y i went for a -3AN line from the get go is that you do not need to use a restrictor. now if you get an oil line kit from whoever and the line is -4AN please DO use a restrictor.

good to hear tho that the problem is fixed and that your not smoking. hopefully nothing serious happened and all is well. happy boosting.

[GEO]

Yep I also run a -3AN line with no rescrictor. I let the egnine cool for about 1 and a half minutes. Good ****!

[KATwo40]

Just thought I'd add that also using a wide ratio oil is not a good idea in a turbo car, especially if it's conventional oil.

I'm running -4an line with restrictor, but I might just switch to a -3an without restrictor. I sure like that idea better.

[j-z]

just some additional info, the reason im running a restrictor on my turbo even with -3 line is this. i was going to a prelude meet when i had the lude running about 90mph in 5th the entire way up to gainsville on I75 (about an hour and a half). car was perfectly fine before i left. when i got there and we all meet up, we were waiting for a few people and then when i went to move my car a lil a BIG puff of blue smoke came out. i was like WTF. i was running a -3 line on that with no restrictor. i believe it was the road trip that killed my turbo after just being rebuilt by a high profile rebuilder. ive always let it cool down for 2 mins. ever since that incident it would puff out blue smoke only after idling for a min or two. yeah i was pissed and ill always use an oil restrictor from here on out. ill just let it cool for 3 mins or so.

[AZhitman]

Yep I also run a -3AN line with no rescrictor. I let the egnine cool for about 1 and a half minutes. Good ****!

George, is that the standard line from IAP?

[BillKlineVT]

I read all that stuff wondering why you're having such an issue with the restrictor, then you say you had a -3AN line, and it all makes sense. It has been discussed before that the while 3AN line has an ID of 3/16", the fittings used for those lines have an ID of about 1/16", aka .060", so no need for a restrictor. Therefore, instead of the previously mentioned moral, I suggest that you ONLY USE A RESTRICTOR FOR 4AN LINES, .060" for journal bearing CHRA's, .035" for Ball Bearing CHRA's. Not sure what you'd use for 3AN lines with a Ball Bearing turbo though...

[MarkEmark]

I read all that stuff wondering why you're having such an issue with the restrictor, then you say you had a -3AN line, and it all makes sense. It has been discussed before that the while 3AN line has an ID of 3/16", the fittings used for those lines have an ID of about 1/16", aka .060", so no need for a restrictor. Therefore, instead of the previously mentioned moral, I suggest that you ONLY USE A RESTRICTOR FOR 4AN LINES, .060" for journal bearing CHRA's, .035" for Ball Bearing CHRA's. Not sure what you'd use for 3AN lines with a Ball Bearing turbo though...

Well I guess my feedline isn't -3 then, because the inner diameter of the hose is definitely NOT 1/16"....that is VERY small. Not even the restrictor I was using was that small...as mentioned in the previous post, it wasn't a .060" restrictor, it was .075". I just measured the actual inner diameter of the braided line, not the fitting, and it's 3.7 mm, or 0.15" (3/16" = 0.18"). So the moral stands: I was using larger than a -3, and an even BIGGER restrictor than what everyone else uses, and this still happened.

Here's a picture of the oil restrictors: the larger one is the one I used; the smaller one is the popular .060" one from ATP turbo:



Here's a picture of *one* piece of the coked oil that was blocking my drain-line:



Regarding not changing the oil in 2000 miles: I changed it after 1000 miles, so the oil was only in the engine for 1000 miles. Not to mention, I'm not blaming the oil for this. 5w30 is what is recommended by nissan, and it's what I've been running since owning the car without any problem.

Modified by MarkEmark at 6:59 PM 6/26/2006

[BillKlineVT]

Well I guess my feedline isn't -3 then, because the inner diameter of the hose is definitely NOT 1/16"....that is VERY small. Not even the restrictor I was using was that small...as mentioned in the previous post, it wasn't a .060" restrictor, it was .075". I just measured the actual inner diameter of the braided line, not the fitting, and it's 3.7 mm, or 0.15" (3/16" = 0.18"). So the moral stands: I was using larger than a -3, and an even BIGGER restrictor than what everyone else uses, and this still happened.

Hmm, how'd you measure the inner diameter of the hose if there are "ends" crimped on the end of it? That's what I meant by the ID of the "fitting" - the hose ends. I'm just going by hearsay on the -3AN stuff, but a reputable guy (JGSTurbo on the ka-t.org forum) who sells oil feed line kits, said that the ID of the hose ends used for -3AN lines are roughly 1/16", but then again I'm sure there are different types of hose ends, and obviously yours have much larger openings.

cross-quoted from the ka-t.org forum...

Most of the teflon lines available have 4AN fittings but 3/16" ID lines and then the fittings used have around 0.100" ID... Then going to a 3AN teflon takes everything down a 1/16" ish

THe problem with 3AN lines is they are rare and good fittings are uncommon

Taken from this thread... http://www.ka-t.org/forums/vie...t=3an

[Jookmasta]

geez thats a big chunk of oil. what brand of oil were u using? i know it was regular oil but maybe some sort of defect? and yes, turbo timer set for at least 2 minutes always.................

[MarkEmark]

Hmm, how'd you measure the inner diameter of the hose if there are "ends" crimped on the end of it? That's what I meant by the ID of the "fitting" - the hose ends. I'm just going by hearsay on the -3AN stuff, but a reputable guy (JGSTurbo on the ka-t.org forum) who sells oil feed line kits, said that the ID of the hose ends used for -3AN lines are roughly 1/16", but then again I'm sure there are different types of hose ends, and obviously yours have much larger openings.

cross-quoted from the ka-t.org forum...

Taken from this thread... http://www.ka-t.org/forums/vie...t=3an

It was very easy to measure. I stuck a metal scribe into the hose and measured it where it stopped. I don't care about the ID of the fitting, the ID of the actual hose is what matters. And my measurement is exact. I don't think my braided hose is exactly a -4 either; if it were, the OD should be .25" and it's not.

You guys seem to be missing the point. It's not the oil's fault, it's not the size of my feed-line's fault, it's the oil restrictor's fault, by not flowing enough oil through the turbo causing it to coke under hot temperatures. Keep in mind this car is not beat by any means, and it's certainly not raced. This happened during regular daily-driving conditions under reasonable ambient temps of ~75 degrees. Again, it's impossible to know if the oil coked during driving or during idle, but I can guarantee you I'm every bit as conscientious as every other KA-T owner in letting the engine cool down before shutting it off...the engine is not in boost for the last 1/2 mile of the drive, and was always idling for at least a minute before shut off. That should be MORE than adequate. Oil was Pennzoil 5w30, the same oil I've been using since day 1, and the same oil that was used for 4000 miles with my older turbo (NO RESTRICTOR). Again, NOT the oil's fault.

[BillKlineVT]

I don't care about the ID of the fitting, the ID of the actual hose is what matters.

Not really... the smallest ID will present additional restriction to the fluid flow - hence the idea of a restrictor. Anyway, since you seem to be content on that aspect, I guess there's no point in arguing the fact. The pics you posted of the oil coking is unbelievable though - I guess since the turbo isn't water cooled, the flow of oil is that much more important since it's used for cooling as well.

On second thought... I suggest you pull the oil pan off and check the oil pickup screen to see if it's clogged at all. If there was that much junk blocking your return line, who knows what's floating around in your oil pan! That'd be a big bummer if you spent all that money on a built motor and it was starved of oil from a blocked pickup screen

[tvmendoza]

Hello, i have a problem similar to you, my turbo started burning oil like a month ago so igot an oil restrictor the problem decreased but there was that white/blue coming out of my mufler, and there was oil on the compresor of my turbo. SO i re-built the turbo and the smoke is still there. But it is only when i am at idle, if i am crusing or wot it does not smoke, so if i get into a light it will start smoking and then when i go it smokes more(just the first time i step on it) but then it desapers. I am using the jgstools lines kit and an oil restrictor, should i put off the restrictor?

I hope everyone understands.ThanksTona

[MarkEmark]

Not really... the smallest ID will present additional restriction to the fluid flow - hence the idea of a restrictor. Anyway, since you seem to be content on that aspect, I guess there's no point in arguing the fact. The pics you posted of the oil coking is unbelievable though - I guess since the turbo isn't water cooled, the flow of oil is that much more important since it's used for cooling as well.

On second thought... I suggest you pull the oil pan off and check the oil pickup screen to see if it's clogged at all. If there was that much junk blocking your return line, who knows what's floating around in your oil pan! That'd be a big bummer if you spent all that money on a built motor and it was starved of oil from a blocked pickup screen

I don't understand why you're arguing with me. The whole purpose of this post was to offer a caveat for the traditional school of thought saying "d00d, run an oil restrictor or you'll blow your sealz". But when people have running commentary and start nitpicking at what I have to say, it's what makes me want to not contribute to this forum in a positive manner.

I measured the ID of the fitting, the smallest restriction present in the line.

Good point about the oil pan, but I doubt there's any chunks of that coked oil in the oil pan. As I said, the car was run for only about 10 miles with any smoking, and I needed to dig that chunk out of the center section, it wasn't just floating around...if those chunks had flowed down the oil return line and into the pan there wouldn't have been any oil blowing by the seals. When I drained the oil and switched to synthetic it was very clean and a good color. Maybe some rainy day when I feel like crawling back under i'll drop the pan, but it's such a PITA.

Tona-as has been said, if you're running a -3, don't use a restrictor. If you're running a -4, use at your own risk. I personally would never run a 1/16" restrictor--just take a look at one of the pictures at how tiny that hole is. I'd run at smallest a 1/8", or if you do run smaller, make damn sure you take a ridiculous exaggerated amount of time to let the turbo cool down (wasting gas, time, etc). But if your car is only smoking at idle and not under acceleration, it's not the same as my problem. Mine definitely smoked under acceleration. Does yours smoke when you let off the throttle and are in vaccuum? If so, it could be your valve seals. A leak down test would be the best method to see whats what.

Modified by MarkEmark at 4:33 AM 6/27/2006
Modified by MarkEmark at 8:34 AM 6/28/2006

[BillKlineVT]

I don't understand why you're arguing with me. The whole purpose of this post was to offer a caveat for the traditional school of thought saying "d00d, run an oil restrictor or you'll blow your sealz". But when people have running commentary and start nitpicking at what I have to say, it's what makes me want to not contribute to this forum in a positive manner.

Sorry for getting you all riled up... seems there's been a misunderstanding - I'm not giving you ****, just trying to make clear what you're trying to prove... with wording such as "If you're running a -4, use at your own risk," that's not a very definite answer for people that may find this post in a search in the future. Also, about my "nitpicking" and "running commentary," what's the point of having a message board? To discuss, and discussions usually have more than one person involved. Are we to assume that all information you give is 100% correct for everyone's unique situation?

The ID of a hose fitting is NECESSARILY LARGER THAN THE ID of the hose, hence the reason I don't care about the ID of the fitting. This should be self-evident. If it weren't larger, it wouldn't be able to screw over the male end.

LOL, obviously... I wasnt talking about the THREADED part of the hose end, I'm talking about the part the oil actually touches. I guess that's what you measured. Pretty sure what you measured was a part of the hose end and not the actual hose material.

Here's a pic to clarify the situation:

What I was getting at with the quote from JGSturbo was that the ID (that I have pointed out in green in my awesome pic) is not always the same size (usually smaller) as the ID of the hose. In your case, the ID of the hose END was .15", which is probably because you're using 4AN teflon hose which has a nominal ID of .19" (varying based on manufacturer), and the fitting is slightly smaller at .15".

With people getting their oil lines from various sources, these ID's will vary slightly, giving different results for different people. If you really want to have the ideal oil flow to your turbo, why not hook up an oil pressure gauge to the feed line, and use an "adjustable restrictor" such as a needle valve. That way, you can find the optimal restriction based on the turbo manufacturer's maximum oil pressure for the center section (before leaking out the seals, that is.) Once again, this maximum pressure will be achieved at higher RPM and engine load since that's how the oil pump works, so that will still result in a lower-than-ideal oil pressure at idle. Anyway, I'm sure the turbo manufacturer had that in consideration when designing the CHRA.

In my case, my GT series turbo is water cooled, so I'm not so greatly affected by this issue of oil coking. I run a .035" restrictor (due to ball bearing CHRA) in my 4AN JGS feed line, and have zero oil smoke. I've run it this way for about 1.5 years now, and before that I ran a t25 with a .060" restrictor for about 6 months, also with no issues of oil coking or smoke. I've taken my return line off numerous times to replace turbo-mani gaskets, etc, and never have I found any coked oil in the return line or the center section. I don't go crazy (ie. any longer than a minute) with the cool-down cycle either, with the exception being if I just was on the track or something. The water cooled CHRA was designed to have the coolant "thermosyphoned" (a thermal-mechanical phenomena) through the lines after the car is turned off, which is a pretty neat idea if you ask me.

edit: what happened to the "preview" option for posting threads? I've edited this post like 3 times for proofreading/clarification
Modified by BillKlineVT at 7:54 AM 6/27/2006

[MarkEmark]

Sorry for getting you all riled up... seems there's been a misunderstanding - I'm not giving you ****, just trying to make clear what you're trying to prove... with wording such as "If you're running a -4, use at your own risk," that's not a very definite answer for people that may find this post in a search in the future. Also, about my "nitpicking" and "running commentary," what's the point of having a message board? To discuss, and discussions usually have more than one person involved. Are we to assume that all information you give is 100% correct for everyone's unique situation?

LOL, obviously... I wasnt talking about the THREADED part of the hose end, I'm talking about the part the oil actually touches. I guess that's what you measured. Pretty sure what you measured was a part of the hose end and not the actual hose material.

Here's a pic to clarify the situation:

What I was getting at with the quote from JGSturbo was that the ID (that I have pointed out in green in my awesome pic) is not always the same size (usually smaller) as the ID of the hose. In your case, the ID of the hose END was .15", which is probably because you're using 4AN teflon hose which has a nominal ID of .19" (varying based on manufacturer), and the fitting is slightly smaller at .15".

With people getting their oil lines from various sources, these ID's will vary slightly, giving different results for different people. If you really want to have the ideal oil flow to your turbo, why not hook up an oil pressure gauge to the feed line, and use an "adjustable restrictor" such as a needle valve. That way, you can find the optimal restriction based on the turbo manufacturer's maximum oil pressure for the center section (before leaking out the seals, that is.) Once again, this maximum pressure will be achieved at higher RPM and engine load since that's how the oil pump works, so that will still result in a lower-than-ideal oil pressure at idle. Anyway, I'm sure the turbo manufacturer had that in consideration when designing the CHRA.

In my case, my GT series turbo is water cooled, so I'm not so greatly affected by this issue of oil coking. I run a .035" restrictor (due to ball bearing CHRA) in my 4AN JGS feed line, and have zero oil smoke. I've run it this way for about 1.5 years now, and before that I ran a t25 with a .060" restrictor for about 6 months, also with no issues of oil coking or smoke. I've taken my return line off numerous times to replace turbo-mani gaskets, etc, and never have I found any coked oil in the return line or the center section. I don't go crazy (ie. any longer than a minute) with the cool-down cycle either, with the exception being if I just was on the track or something. The water cooled CHRA was designed to have the coolant "thermosyphoned" (a thermal-mechanical phenomena) through the lines after the car is turned off, which is a pretty neat idea if you ask me.

edit: what happened to the "preview" option for posting threads? I've edited this post like 3 times for proofreading/clarification

Modified by BillKlineVT at 7:54 AM 6/27/2006

Yes, I don't know why I thought you were referring to the thread ID size...I measured the inner diameter of the fitting (the green in your picture), ie, the smallest diameter area of the whole line, and got .15". I just don't know why you were questioning whether that was the smallest diameter present or not.

As far as a needle valve in the feed-line and a pressure gauge-i'm already one step ahead of you and was planning on doing this. That'd definitely be the best way to make perfectly sure you're running optimal pressure to the turbo, but again, the pressure obviously varies quite a bit based on idle or driving and I don't know how I feel about running an oil line with a gauge into the cabin...I guess it'd be fine to do temporarily.

Nonetheless, if a -3 hose has an inner diameter of .13" (according to Pegasus Auto Racing), why would the actual smallest ID of the whole set up (the fitting) be exactly 1/2 that size? I'm not doubting that it's not, but it seems pretty misleading! Say you want an inner diameter of .13" for the line but the smallest part of it is really .0625?!?. There's a big difference! Why don't they bother telling you the smallest diameter of the whole set up (the green line in your picture), which is what really matters?

The reason I'm saying to use a restrictor at your own risk with a -4 hose is because some people swear by it and say it's necessary and eliminated oil being blown past turbo seals, but for me it was the very reason oil started blowing by my turbo seals (after the oil coked due to insufficient oil flow in/out of the turbo), and again, this was after using a larger (.075") restrictor than what everyone else suggests/uses.

What sucks is that there DOESN'T seem to be a definitive answer on the issue, but I'm still convinced .060" is too small. Maybe i'll drill out one of those restrictors to .10".

[BillKlineVT]

As far as a needle valve in the feed-line and a pressure gauge-i'm already one step ahead of you and was planning on doing this. That'd definitely be the best way to make perfectly sure you're running optimal pressure to the turbo, but again, the pressure obviously varies quite a bit based on idle or driving and I don't know how I feel about running an oil line with a gauge into the cabin...I guess it'd be fine to do temporarily.

You can always run an electric gauge... no oil to the cabin that way. It'd be interesting to see what you get as an opening size with the needle valve if you do end up testing it this far in depth.

[nb07bcar]

I was told to run no restrictor to a journal bearing and run a restrictor to a ballbearing. This was told to me by garrett. They said if you don't have above 75 psi it should blow through your seals. This what I've always been told

[Jookmasta]

well i run an oil line to the inside of my cabin. its a lovely 10 ft. -3AN ss line. yes their is more risk with the mechanical but it can be done safely. tho i would go with electric if i could do it again.

[crzycav86]

I think this has been one of the more useful threads to come out of this forum in a while. Good discussion.

[BillKlineVT]

well i run an oil line to the inside of my cabin. its a lovely 10 ft. -3AN ss line.

WOW, how much did that run you? Do you own a SS line manufacturing company or somethin? Hehe

I think this has been one of the more useful threads to come out of this forum in a while. Good discussion.

Glad someone appreciated it!