Running -3an Feedline Instead of -4an Discussion

[GNVYUS 1]

Corky Bell explains that a turbo only needs 35psi of oil pressure to adequately lubricate a journal bearing turbo. Most of us have 60psi of oil pressure minimum at WOT and some of us are 70 to 80psi.

The stock line is definitely smaller and if Buick engineers thought we needed a bigger ( more volume ) line they'd have put one on the turbo. A lot of us like myself have smoking issues yet the turbo has no play and most likely it's the volume of oil being pushed passed the seal leading out the DP ( new motor 1200miles ).

So recently I saw a post of a shop that found almost 10whp on a dyno from adding a 1/16th reducer on a shop's turbo feedline, they were measuring the lines psi. Sort of like the effect a crank scrapper has on a rapidly moving crank.

I never paid attention but my Talon's kit came with a -3an line and the PTE Turbo Saver is a -4an and it used to be -6an but was changed due to smoking issues from posts I read in the past.
I'm going to either buy a 1/16th reducer and do dyno pulls Oct 18th and see if this fits the info I've been reading. I'm actually having a hard time finding the reducers??

What's your take on this?

 

[ttypewe4jim]

Corky Bell explains that a turbo only needs 35psi of oil pressure to adequately lubricate a journal bearing turbo. Most of us have 60psi of oil pressure minimum at WOT and some of us are 70 to 80psi.

The stock line is definitely smaller and if Buick engineers thought we needed a bigger ( more volume ) line they'd have put one on the turbo. A lot of us like myself have smoking issues yet the turbo has no play and most likely it's the volume of oil being pushed passed the seal leading out the DP ( new motor 1200miles ).

So recently I saw a post of a shop that found almost 10whp on a dyno from adding a 1/16th reducer on a shop's turbo feedline, they were measuring the lines psi. Sort of like the effect a crank scrapper has on a rapidly moving crank.

I never paid attention but my Talon's kit came with a -3an line and the PTE Turbo Saver is a -4an and it used to be -6an but was changed due to smoking issues from posts I read in the past.
I'm going to either buy a 1/16th reducer and do dyno pulls Oct 18th and see if this fits the info I've been reading. I'm actually having a hard time finding the reducers??

What's your take on this?

I have not done this with the buicks but........... On some turbo mustangs (please dont kill me for saying that :biggrin: ) people run a nitrous jet in the line to act as a reducer. If you poke around on The Turbo Forums.com you will see what they do I can not recall the size most people use atm but I will try and find some good post on it.

hth

 

[RUQWKNF]

Here is what I learned at PTE.

The 4G63 application feeds from the cylinder head from the factory and has very little oil to begin with that feeds the turbo. A -3 line is sufficient for this application. When the first T3/T4 journal bearing Mitsu turbos first came out, people were reporting failures due to oil starvation. This was mainly due to the fact that they were still pulling oil from the head, and not from the oil filter housing. Once this remedy was put in place, the failure rate dramatically dropped. It was determined that the oil feed from the head, was not a sufficient or steady supply of oil, but rather a highly airated and foamy source of oil.

All other journal bearing Garrett T3 or T4 based turbos, whether they be Domestic or Import need to have a -4 AN feed line with no restrictor. In some specific T4 race applications, a restrictor fitting or in some rare cases a -3 line can be used. It all depends on the volume that the feed source puts out and the maximum psi it will supply. Journal bearing turbos, do not like pressures over 80-85psi. We typically try to keep WOT oil pressures below 85psi for longevity reasons.

Buick turbo V6 applications not using the stock oil feed line, whether they be a stock '86-'87 or a TSO race application, utilize a -4 AN feed line. Going to a -6 AN line will flood the cartridge and blow out the oil seal.

Dual Ball Bearing cartridges are a whole other subject. The Garrett DBB cartridge, does not require as much oil volume as their journal bearing cousins do. The -4 AN size in some cases can actually flood the cartridge with too much oil and cause some leaking issues. This DBB cartridge, does not use the standard oil seals like the journal bearing models do. Therefore it is more susceptible to flooding and leaking.

I do not recommend running any restrictors on journal bearing turbos for Buick applications. This can lead to oil starvation issues. If you have oil leaking from the turbo, either the pressure is too high and has caused damage to the seal, or the seal has been damaged from excessive loading of the seal.
Now that I've said that, there have been some PT70 and PT71 Buick owners who reported oil leaks with brand new turbos in the past. And some have gone against recommendations and ran oil restrictors to cure the problem.
This could have been caused by clearance issues in the bearing housings, causing a poor seal fit, who knows. Everything from Garrett is inspected by their own QA department before the parts are shipped. So, who really knows.
If it worked for them, good to go. But I would never recommend starting from scratch with a restrictor on a journal bearing turbo, especially if you know your oil pressure at WOT is below 80psi. I would run the turbo first, check for signs of oil leaks after a few hundred miles, then if need be, address the situation.

One last thing you need to keep in mind is, if you put this turbo on at the same time of a recent motor rebuild, there is a very good chance that break in particles could have damaged the turbos oil seal. Even with 1200 miles, all it takes is particles making their way to the cartridge and coming into contact with the seal while the rotating assembly sings along at 130k plus RPMS at WOT. Then the rotating assembly gets slammed backwards under decel whatya know, damage can occur. The only real way to know if the seal has been damaged would be a tear down inspection by a reputable turbo shop.

Large T5 & T6 size turbos need not apply here.
That book has some good info, but alot of it has become quiet antiquated with todays more modern technology. That is, if you are referring to this book.

Hope some of this helps a little.

Patrick

 

[GNVYUS 1]

My Talons turbo does get feed from the filter and the stock head is a dirty source of oil which was another cause of those dying. The DSM's run a filter off the head for the BB turbo's along with a restrictor in them. But the fact that Mitsubishi knew the head had lower oil pressure gets to my point in the first place.

If we don't need more than 35psi than why run a -4 at 60psi?
The stock line is smaller and is fine so why even use a larger -4 line, why didn't they come with a -3 in the first place to cut down on the volume?

And my turbo slightly smoked on the old motor and it had higher oil pressure, but the turbo is rock solid tight luckily.

 

[jpwalt1987]

I have on of the first PTE turbo savers that came with the -6 line. The turbo is a old school pt70-1. It has about 1200 miles on it,always with the turbosaver. I was having a smoking problem and it turned out it was from the oil seal in the turbo. After much debate and thought I made a restrictor. I tapped out the inlet side of the AN fitting going into the turbo to accept a set screw. I drilled out the set screw to about .100 -.120. I cant remember which. I checked oil volume by spinning the oil pump with a drill. Needless to say I dont see any way it could be starved for oil. The original size in the fitting was about .210-.250. I just wanted to reduce the volume of oil a little. I dont have any more smoking problems either......well except for the tires

 

[brian_k03]

-3 is just fine regardless of size of the turbo water cooled or not.

 

[GNVYUS 1]

Exactly, the fact that PTE had a -6 on first says they didn't think about this issue prior to releasing the Turbo Saver. I believe the -4 is still too big considering there isn't a restrictor and how many stock turbo's or those still running the stock feedline have turbo seal issues?

 

[disco stu]

If you look at the supplied fitting of Precisions turbos now, you will see that there is a restriction orifice on the bottom of the fitting is about .020.

 

[GNVYUS 1]

Aha, I got my TA49 rebuilt in like 02 so I'll call them and get that fitting. Much easier than buying a new braided -3 line.

I'll still do the dyno anyways, can't take more than 5 minutes to swap it out and see.

 

[salvageV6]

The pressure on a gauge located at the turbo fitting will actually go up when you put a restriction on the line feeding it.

Kinda funny how that works but I guess as long as the volume is lower they don't leak/burn as much.

Worked for me, I use .075" on my Innovative DBB.

Pressure went up over a journal bearing turbo just by bolting the new turbo on there, as the cartridge itself has some restriction in it different than the typical journal bearing turbo.

Went up more after the line was down to .075".

 

[V6RACER]

Less oil to turbo, means more oil to important bearings in the bottom end.

 

[RUQWKNF]

Stop, hold it, wait!!!!

That supplied fitting that disco stu is referring too, only comes on Dual Ball Bearing turbos from PTE. Not their journal bearing turbos. That special restrictor fitting is a tapered flare restrictor fitting that was specifically made to mate to the internal jet that is inside every Garrett dual ball bearing turbo.
That special, silver aluminum restrictor fitting, will not work on regular journal bearing turbos. Especially not on a TA-49. Their journal bearing Buick 3-bolt turbos, include the OEM brass 90* elbow fitting that is used on the OEM oil feed line. Just wanting to clarify before somebody runs off and buys one of PTE's restrictor fittings, thinking it will screw right into a journal bearing turbo. Won't happen. And yes, in the beginning when the turbo savers first came out, they did have -6 feed lines. After numerous turbos leaking oil, the design was altered and included a -4 braided feed line. I still stand by what I said earlier. I have been running the -4 feed line on all of the Precision Oil Savers on all of my Buicks. On my old Grey car, I used the same Oil Saver kit on 4 different turbos without ever having a problem. I did have to buy a new line because the fitting broke on me one year, but I never had a turbo leak oil using their -4 feed line in their Oil Saver. And all 4 turbos were Garrett journal bearing turbos.
Carry on with the debate.....


Patrick

 

[GNVYUS 1]

I'll have to measure the current fitting opening in my TA49 then and get back here. It would be easiest to just swap out this fitting with a 1/16th smaller ID opening like many have done in the Import world.

I never thought about the oil pressure build up for the other parts since the turbo will need less but it can't be that much with a 1/16th reducer.

BTW, I swapped the WIX 51049 filter to a Mobil 1 203 and gained around 3-4psi of total flow, I'm back to 60psi. Mobil 1 is made by Champion so they aren't the same filter FWIW.

I'll report back on current ID of fitting, any power gain from dyno ( doubtful ) and any total pressure gain at start up.

 

[disco stu]

Stop, hold it, wait!!!!

That supplied fitting that disco stu is referring too, only comes on Dual Ball Bearing turbos from PTE. Not their journal bearing turbos. That special restrictor fitting is a tapered flare restrictor fitting that was specifically made to mate to the internal jet that is inside every Garrett dual ball bearing turbo.

Oops, thanks for the correction.

 

[mygn276]

For years i always had a smoking problem on my GN and thought it was from valve seals or guides. Even seen this problem on other buicks. After searching the turbo forums i found the mustang guys are restrictors in there feed lines to the turbo that solves reduces the oil pressure. I installed a .060 restrictor in mine and no more smoke.

 

[GNVYUS 1]

Can you post a link to where you got it so we all have a reference in here?
I'm assuming you're running the Turbo Saver -4 line?

Here's what I'm seeing here.
JP has the original fitting ID at about .210 to .250.
Mygn added a .060 restrictor to stop his from smoking.
You get around .150 to .190 total ID size needed for smoke free journal turbo's??

Salvage has a .075 ID on his BB turbo which appears to be X2 as small after a .060 reducer is added to the journal bearing turbo's oil fitting.

JP how many miles on your oil fitting restriction setup?

 

[1BADTT]

Great info !

Subscribing...

 

[ijames]

Not commenting on whether or not you should do this, but we buy precision flow restrictors from McMaster-Carr. We use part 2822T181, just put that in the search box and then look over that catalog page to see what they offer. Great customer service; we buy lots of hardware from them. Corky also emphasizes that you need to make certain that the drain line isn't restricted as that will back oil up into the cartridge and past the seals.

 

[GNVYUS 1]

I didn't see the above post but just ordered this from Summit.

-3an, 90 degree, 1/8th npt male nickel fitting = Rus-642791 = need 2 = $20

-3an hose ends, nickel = Rus-620131 = need 2 = $22

-3an, 6ft SS braided hose, .125 ID = Rus-632500 = $24


The -4an hose ID is .220 and a -6an is .343 ( some brands are slightly different ).
I'd suspect going from a -4 fitting end to a -3 will also reduce the ID, maybe they match the hose ID's above?

FWIW this is a similar oil feed kit that came from AMS for my Talon's 6152S turbo and that been fine for over 18k miles now.

 

[ijames]

Just reread what I posted and I want to make it clear that we aren't using those restrictors on turbos, we use them in carbon dioxide gas lines in incubators that we build at work. We use a pretty small size; I just gave the part number to make it easy to find the catalog page so you could look at all the sizes they offer.