Turbo oil return line size

In response to a couple of posts in this thread:-

http://www.mkivsupra.net/vbb/showthread.php?p=1182884#post1182884

Posts 134, 141 and 142

and rather than chog the thread up with a discussion on oil return sizes, I thought I would ask a few questions to see what peoples opinions are.

I agree that the output from the turbo could well do with being say -10 or so, but I've then got a couple of options.

I can run -10 lines all the way.

OR

I can waste it down to the -6 that I already have.

My reasoning for this is that although the oil is "whipped up" by the bearing on the turbo, once it's into the line itself, it's just oil in a line isn't it? And seeing as the outlet is larger than the inlet, the pressure differential is going to be less so it shouldn't ever be a problem?

What do you guys think? I've not really got any preference to either, just throwing some idea's out there....

Cheers.

Tony Oil feed to the turbo is under pressure but the oil return from the turbo is purely down to gravity, the bigger the line and the more direct downward route to the return flange the better. Going from a -10 to a -6AN size would be introducing a bottle neck so to speak. As the oil return is very important you dont want anything to hinder this, things like Badly routed oil return line, Positive Crankcase pressure through a bad evac system etc etc can cause a build up of oil pressure in the bearing housing which usually results in oil being pushed by the seals.

What have Blitz recommended for your setup Tony? They must recommend certain size, surely?

What have Blitz recommended for your setup Tony? They must recommend certain size, surely?

Nope. They supply a crappy push on fitting that's maybe a little bit larger than a -6. Pretty sure it's not as big as -8 though.

You have to remember, this kit comes with no installation instructions at all. Absolutely nothing.

Tony, All I can tell you is that my T61 was -10 all the way into the block....so your two turbo's must at least replicate that and enter the block through 1 or 2 -10's. Basically as it's only gravity driven you have to give it as much assistance as is possible.

This is why the turbo has to be set with the oil exit at 180deg's (ie straight down not on the wonk). Any angle at the start of the run is going to inhibit getting that spent and very hot oil away from the cartridge...and you don't want it dwelling there after it's done it's job as this will increase temps and prevent cooler oil entering properly. I've seen a lot of turbo's set at an angle from a certain tuner...if yours is at an angle it's wrong wrong wrong get the tuner to sort it out asap FOC! This is/has reduced the life of your turbo.

But back to the point for Tony, it's basically as big as you can fit in there. Get the heat away!

I use 5/8" bore minimum, preferably 3/4" bore.

Ok chaps, I've gone for -10. I don't know if it will fit at the bottom, I may well end up having to swap the powersteering fitting around if it's possible.

Anyway I picked up the parts this morning:-

along with 2 metres of -10 hose, which will hopefully be enough for the oil return lines and the PCV vent. £220 lighter of pocket though!! Plus it looks like I'm going to have to modify the -10 to M18 fittings I've got. They're going to be too long for the flanges I've made, and also where it steps down to M18, there's quite a restriction (Probably about the same as if it were -6 ) But there's a good 3-4mm wall thickness so I'll drill it out to something a bit more substantial.

Cheers for the advice guys.

there must be at least 1000quids worth of aeroquip fittings on your car by now

It's easily done. Silly silly expensive, dunno how the manufacturers justify it, TBH. Still if we keep writing the cheques....

there must be at least 1000quids worth of aeroquip fittings on your car by now

Without adding it up, I would probably pitch it at about £1400 or so. (Don't tell the missus!)

I wonder if I'll walk outside the house one morning to find the car won't start because some scroat has knicked all the hoses and fittings... Probably worth more than some of the shitters out there! LOL.

aeroquip was originally for aircraft use and thus the prices! the cost of a hydraulic line fail on an aircraft can run into 10s of thousands of pounds,so reliability is paramount ,the race car fraternity soon latched on to the use of aircraft fittings for light weight and reliability and hence aeroquip sold to the motor market

and saw no need to reduce prices,

same deal with the race car electrical connectors /wiring /composites/alloys all started via aircraft industry and all bloody expensive

Talking about electrical connectors...

As Spyker road cars exclusively use Lemo electrical connectors, we now get them for free!

Not quite as good as Deutsch connectors, but heh, beggars can't be choosers! Here's an example:-

http://www.lemo.com/browse.do?page=5&groupCollectionID=M&groupID=F&seriesID=5&groupName=&insertStyleID=3&terminationStyleID=2&typeCriteria=*&sizeTypeID=1F.308&sizeTypeCode=194&modelCriteria=*&plasticCriteria=*&watertightCriteria=N&shellStyle1=0&shellStyle2=4&pbSubmit.x=52&pbSubmit.y=11

Next winter I'll be building a new complete electical loom

You would be suprised at the weight saving doing your own looms and connectors,you can also fit a master circuit breaker panel and do away with the crappy fuse box ,also add breakouts for diagnosis and faults.use thinner cables as there is always some leeway in cable capacity helps if you keep loom thickness to a minimum and run an extra loom as heat is reduced,on important looms ie for fuel pumps quality cable will reduce volts drop too

IIRC the bore through the fittings is usually a lot smaller than the hose bore size. I'd size my minimum diameter to the fitting bore and chosse a slightly larger pipe bore, is possible.