Choosing turbo feed sizing?

[7Mboost]

What kind of things do we need to know to choose a correct size turbo feed? Is there a range, or what turbo specs do we need to know before choosing our sizing? Also thought this may be some helpful information, and I want to know what size I should run for my setup.

I ask because my brother's t67 just blew, again, this will be the third rebuild and I was talking with the turbo rebuilder and he seems to think its not the turbo (of course because he built it but) but something to do with the feed sizing or pcv ventilation? He is running a -4an feed right now with a restrictor but he still thinks its too big, he suggests a -3an, expert input wanted thanks!

 

[IJ.]

If it has a restrictor you could feed it with a -12 hose and it wouldn't make a spec of difference the system can only flow as much as the point of greatest restriction full stop.

If the PCV/Drain is suspect there will be signs of it flooding the labyrinth seal and LOTS of smoke.

 

[7Mboost]

We found oil leaking between the center cartridge and the exhaust housing coming through the bolts that hold CC to EH. There was no smoke coming out of the exhaust, no smoke on deceleration, and what looked like rich black smoke when we pushed it into boost. The PCV system he is running now is...well I'll have to get a picture but its not pretty and now that you say that I suspect that is the problem. But I would still like to know about choosing feeds.

 

[IJ.]

BB turbo you can get away with a small feed (-4 here maybe -3 from memory)
Early BB turbo's didn't have the built in restrictors and would flood badly.

Plain bearing needs much more Oil, but conversly need a perfect unrestricted drain and a correctly functioning PCV system so there's no + pressure in the crankcase.

 

[mhopemk3]

Jeff,

I have a new MP Turbo and was told (by the manufacturer) they usually run -3 feed lines. MP turbo's are journal bearings. I am going to run a -4 because those are the fittings and stuff I already have. However, they told me to try the -4.

 

[7Mboost]

What size MP are you going with Matt?

 

[annoyingrob]

Just curious, what's the shaft play like end to end?

 

[mhopemk3]

What size MP are you going with Matt?

I have a cast Turbonetics T4 manifold (Ceramic coated), Driftmotion HKS style WG, AEM 4" DRYFLO filter and the MP T64 with antisurge housing sitting on the floor in the house awaiting installation. I need to have the vbands welded on the downpipe and then make a 4" intake pipe.

 

[7Mboost]

The turbo is being rebuilt again, the builder found more metal shavings, its most likely shavings from when the 1jz crankwalked, because the 1.5jz isn't making any noizes or giving us any problems, so hopefully this will be the last rebuild, I will post a picture of the pcv later tonight to make sure its not a problem and just make sure everything is right so we can get this car on the road.

Nice setup Matt! We must run when I get my shit on the road.

annoyingrob- The turbo builder said he only had to cut the shaft I think 0.003.

 

[7Mboost]

Ok here's the SC pcv setup, its goes from right cam cover to left cam cover out through the cam cover size black hose to the catch can where it is downsized via small hose inside the bigger hose, out the catch can through the downsized hose size hose and into the intake pipe.

Also I never really got a clear answer on how to choose correct size feed, what things do we need to know to determine this?

 

[7Mboost]

Ok here's the SC pcv setup, its goes from right cam cover to left cam cover out through the cam cover size black hose to the catch can where it is downsized via small hose inside the bigger hose, out the catch can through the downsized hose size hose and into the intake pipe.

Also I never really got a clear answer on how to choose correct size feed, what things do we need to know to determine this?

 

[frontierguy25]

I had my turbo blow 2 times because of the filter that I had. My turbo was not ball bearing so there is no point for that filter. I run a -4 line on my turbo with no filter and have never had a problem with it since. The filters have little screens on them and will damage over time. That was the problem I was having and right before the third rebuild my local turbo shop told me to bring in all my oil and water lines and they put the filter through a pressure test and couldn't get any pressure through it. Stick with the -4 line with no filter and you'll be set.

 

[MDCmotorsports]

As others have stated.

-4 feed line, and -10 return line.

Call it a day.

 

[foreverpsycotic]

Jeff,

I have a new MP Turbo and was told (by the manufacturer) they usually run -3 feed lines. MP turbo's are journal bearings. I am going to run a -4 because those are the fittings and stuff I already have. However, they told me to try the -4.

Just prying (not to intrude too much on this thread) but do you know if that holds true with all MP turbos? I was looking at going to either a a MP t70p trim or a MP t64 O trim after I feel that I have maxed out the holset I am running now, which requires a -3 feed, -10 return.