Running -3an Feedline Instead of -4an Discussion

[1of1547]

Something doesn't make very much sense to me. Patrick has more turbo experience here than anybody. After all he used to work for Precision Turbo. The same brand probably 75% of people run on T/R's. He recommends running a -04 on journal turbos. Why would you want to go to a -03. Granted it is only approx. .06 difference between the two on the ID. Believe me I'm all for thinking out of the box. My car is a prime example. I would listen to somebody that has been around the block a couple of times. Rather than try to reinvent the wheel.

 

[GNVYUS 1]

AMS sells PTE turbo's and they sell a -3an feedline kit for ALL their journal bearing turbo's and they don't smoke from feedline volume issues or seize. You have members on here saying they put a restrictor in their -4an PTE feedline and the smoking stopped, you also have PTE going from a -6 to a -4 to cure smoking problems in the past. You have Corky Bell saying a journal bearing turbo only needs 35psi and a free flowing oil return yet we have 60psi with a -4 ( .220 ID ) feeding a turbo.

For those of us who have tight shafted turbo's yet are smoking, it seems to make sense that we are feeding them with too much oil. So because members on here have restricted flow stopping the problem and a huge seller of PTE turbo's uses -3 kits it's not reinventing the wheel, it's what the real world is doing to stop the problem.

 

[RUQWKNF]

That's a Mitsubishi application though, they did have issues with cartridge flooding and leaking in the beginning. AMS and Buschur Racing figured out the cure for the leaking.

I appreciate the kind words Doug.

I definitely don't know everything, I'll be the first to admit that. :redface: Heck I learn something new everyday when it comes to this stuff. I just know that 99% of the time, journal bearing turbos, whether they be in a Buick or whatever, typically can and do live with a -4 feed line.

Now, there are some examples where excessive oil volume can overcome the applications return line/configuration. I saw this alot when working with customers who were building their first turbo setup and were trying to do it on the cheap. Things like using the wrong types of fittings, (cast tight 90* bend style brass fittings vs proper smooth bend hose ends) and even the wrong line sizes. I even had a guy try to argue with me one time, saying that his -6 return line was enough on his PT101 with a -4 feed line.
High oil pressures can also cause the oil to back up inside the bearing housing, eventually leading to oil seal failure. This is why we don't want more than 80psi fed to the turbos' oil feed line.

There are differences between manufacturers' internal bearing clearances, as well as differences between their allowable tollerances on bearings and oil seals. Then there is the damage that can be cause by the smallest amount of particles/trash in the oil itself that can lead to premature oil seal failure. No one knows exactly why some turbos can live forever with a -4 line and some puke oil for days with the same -4 line. None of the turbo manufacturers real world test the units with pressurized oil to check for leaks before shipping the unit. The oil inside each unit, is simply there for ease of assembly on the assembly line when they are built. This is why I recommended to just try the -4 line first. If it pukes oil like there's no tomorrow, then you can try the restrictor fitting. But honestly, if it was mine and it puked oil on start up, I would contact the turbo vendor direct and handle it accordingly. Stuff happens. Namely UPS gorillas throwing your precious and expensive turbo around before you even get it.
Just remember, it takes very little trash and or material to cause damage too the rotating assemblies internal parts at 130k rpms.
Honestly, this is a debate that can go on forever. Sure would be nice if we could get one of Garrett's engineers to post their official word on this. Where is Timo when we need him?

HTH

Patrick

 

[salvageV6]

Anybody have the ID of the stock feed line?

Or the vendor replacements which should be in the same ballpark.

Been using that on my other car with a PTE51 journal bearing for a ton of miles and years now.

.250" is the OD for the stock flared tube line, never cut one in half to measure the ID, hard to do at the ends where the flare is, unless you have pin gauges.

I'd guess .150"-.180" or so......

I agree with the need for the unrestricted drain lines, sometimes when I sit at a light on a large uphill grade I see some puffs of smoke, running the braided drain line hose that everyone hates because it's 1/2"-3/4" too short.

I think the angle of the drain uphill backs up the oil a lot more on my DBB car anyway, doesn't seem to be a problem on the journal bearing car.

 

[Pronto]

TURBO DRAIN KIT
Brian has a pushlock version that you could cut to lenght as you see fit. That might solve the oil backing up issue.

 

[GNVYUS 1]

I'm trying to find a way to stop a tight turbo from smoking, if the drain's an issue then wouldn't feeding it less oil probably help that also? I suppose I can buy the bigger drain that both G body and Buick GN sell but I KNOW feeding it less oil will for sure lessen the needed drainage so I'll start there and most likely report back positive results like the others in this thread.

I'm referring the to PTE turbo's AMS sells that use their -3 feedline kit, they sell probably more PTE turbo's than all the vendors on this board combined.

I mentioned what Salvage said about the stock ID feedline, no way it's .220 like the -4 braided line so all I'm saying is the factory ID is sufficient for the journal turbo's and I'd bet that ID size is really close to the -3 kit I mentioned above.

 

[salvageV6]

I measured a stock line ID about .170" and it might get swedged down a bit at a bend but didn't cut one and measure the bend ID's.

Cutting one might skew the measurement even with a small pipe cutter being used. Especially since I'm not a plumber.

Right angle fitting I had (probably is aftermarket and not GM) was about .180" at the flared fitting opening which was the most restricted part of the fitting of course.

I'd guess, yes I said guess, the minimum you would see with a stocker and it's bends would be about .160" at the smallest.

And obviously is what is used with most journal bearing turbos.

If anyone has the ID's on the braided line replacements that some companies sell please post them up.

I may have one on the GN, I forget, have to go take a look.

 

[norbs]

I put a psi gauge after the my -3 line at the turbo and the psi might have dropped 3 psi or so compared to a -4 So in my opinon a -6, -4-3 won't matter the center section will only flow so much oil through it. However as the clearance wear the flow may increase and you might lose psi with the smaller line. A -3 line has .0625 inside diameter.

 

[salvageV6]

The Russell -3AN line has a .125" ID, how come yours is so small Norbs.

I still say the pressure goes up after a restriction is put in the line.

Volume obviously goes down.

 

[norbs]

I have measured the fitting hole, in a -3an fitting, the line could be bigger I'm sure. I will check some more -3 fittings here to verify.