18mm thrust spacer and machining turbo housing

[prove_it]

It matters, this is the reason Justin on tuners won't warranty his rebuilds if you feed from the head. Oil pressure can vary too much from the head along with an insufficient oil volume. The stock thrust washer in the turbo is fine with head feeding, but the aftermarkets with the extra oil port require much more oil.

That why FP recommends only feeding from the OFH with a .075" restrictor on mitsu based center cartridges.

 

[prove_it]

Notice the difference? The "upgraded" washer has a larger port which flows more oil. It's better, but only if fed oil properly.

 

[GSTwithPSI]

Quoting prove_it:
It matters, this is the reason Justin on tuners won't warranty his rebuilds if you feed from the head. Oil pressure can vary too much from the head along with an insufficient oil volume. The stock thrust washer in the turbo is fine with head feeding, but the aftermarkets with the extra oil port require much more oil.

That why FP recommends only feeding from the OFH with a .075" restrictor on mitsu based center cartridges.



If you have a properly functioning oil system, you should have plenty of pressure and volume at the head. Hence, Mitsubishi installing a .075" restrictor inline to limit both on the factory cartridge. Sure, if you're running a FP black or some sh*t, you probably wouldn't want to feed it from the head. But any stock frame MHI turbo (even with the fancy super thrust washer) should be fine when fed from the head. MHI calls for 50 psi at about 1 liter/min as a general spec for their turbos. If you can't achieve this with a feed line from the head (restricted at that), you've got other issues to deal with.

Like I said, it doesn't matter where you're feeding the turbo from. What matters is the getting the proper pressure and flow according to your turbocharger's specifications. If you can achieve that from the head, then feed it from the head. If you need to feed it from the OFH, then do so. Either way, you'll want to check the pressure from whatever source you're using and verify it's where it should be. If it's not, you'll need to swap sources to gain more pressure/flow, or install a restrictor to limit them.

 

[donniekak]

More oil holes means more flow. This drops pressure compared to a stock turbo. It's the same principal at work that makes oil pressure go up when you do a balance shaft elimination.

There is a given amount of oil that can flow through the head oil feed line(and its pressure is lower than the rest of the engine due to the cylinder head pressure regulator), add more flow capability to the turbo bearing system, and the pressure drops.

 

[prove_it]

And the turbo front bearings then starves.

Guess these turbos on my bench that failed the front bearings in under 1k miles must have just be junk.......

 

[GSTwithPSI]

Well, maybe they were junk. Maybe not. You won't know until you determine the cause of the failure. I guarantee it wasn't due the OEM thrust design, though.

 

[prove_it]

It wasn't the oem design. The aftermarket thrust washers WILL cause a loss of oil flow to the front bearing if the oil feed is not fed properly.

That's where you need to feed from the OFH, if the thrust washer is NOT OEM. That's how some of the ebay turbos will actually last for a decent time. They are OFH fed. If it's all OEM bearings and thrust surfaces then your fine to feed off the head, if the head isn't shaved and the oil passage is not blocked.

There are several factors effecting the oil flow to the turbo, and the biggest reason I preach to OFH feed, is due to preventing a potential failure. Every single turbo rebuilder will not warranty a low mileage failure due to a head fed cartridge. They all know what I know. It's obvious once apart.

 

[GSTwithPSI]

I've never seen one in person, but the revised thrust washer with the "big" oil hole doesn't really look too much bigger to me. How much to you think that tiny little variation in that tiny little hole affects system pressure?

Again, where the turbo is fed from doesn't matter. The pressure and flow from that source are what matter. You can just as easily overfeed the turbo from the OFH and you can underfeed it from the head. The only way to can make sure you aren't doing either is check the source.

 

[prove_it]

Backside comparison. The oil on the OEM flows through the little channel, then to the middle of the spacer bore. The hole size is barely 1/32nds inch big. It's damn small. The aftermarket feeds more directly with a much bigger orifice to flow oil. This hole measures just over 1/16th inch. A bit more than double the size. The center cartridge needs a small channel to feed this properly though. (this is also a failure point)


Frontside comparison, The OEM washer has just a smooth surface on the thrust face, oil barely flows through this as there is little gap between the washer and thrust collar. The aftermarket has a massive cutback to allow more oil to flow to the thrust surface. The aftermarket also has more surface area to reduce stress in one area.



The combination of the oil flow changes results in a drastically bigger flow area. The way the turbo oil is dispersed from the inlet is that the thrust washer has a signifiganly larger port for flow. Once the aftermarket thrust is fitted, the oil now has a much easier time flowing through the larger port (water, oil, electricity always take the easiest path). In this pic, the white hole is the thrust feed, the smaller black hole is the front bearing feed hole.


Now it's an industry known fact that the oil pressure inside the head of a 4G63 can vary from as little as 3psi to 20psi due to the "dump" style OEM regulator. Add in 3mm lifters and a shaved head and you'd be lucky to maintain proper pressure the turbo needs. Now if the head port mod is done, the regulator replaced with the KIGGLY regulator and you COULD be ok. Like Brett said, you'd have to measure the pressure at the feed.

Hope this helps those who seem to find it hard to believe me, even though they have never torn apart several failed cartridges and researched these issues.

 

[GSTwithPSI]

That's a great run-down, Ryan. Thanks for that.

For the record, I'm not saying you're wrong about the OFH housing being the ideal place to feed the turbo from. No doubt, the OFH is probably the more consistent source for oiling your turbo. That being said, most of us running stock frame MHI turbos will be fine feeding from the head. Once you start adding 3G lifters, porting oil feeds, deleting balance shafts, decking heads, and modifying and turbo thrust plates, you should probably take the time to check the source pressure to the turbo regardless of where it's getting fed from. When you start screwing with the factory oiling system it may deviate from how it was intended to perform. At that point, it's hard to tell how changes to the system will affect other parts of the motor; hence testing being an important part of the equation here.

 

[prove_it]

Right, all those reasons you listed are exactly why it's a general idea to recommend OFH Feeding. Plus with a proper length line, I think it cleans up the engine bay just a wee lil bit.

Glad I could teach ya buddy.

That's why I'm curious about these ebay turbos and how some last and some don't. I do notice some correlation with the oil source. I've had the ebay ones apart, and honestly they are built a bit beefier than MHI (1mm bigger and longer bearings, larger shaft, better thrust design), but you can't rebuild them so once they go, it's a paper weight.

I'm still on the fence about component balanced versus VSR balanced. VSR is best, but component balanced seems to work as long as the oil there.

 

[EHmotorsports]

I had a China made turbo in my talon for about 4 years and it's also been on the galant for 2. So far so good. One thing I might add is I flushed the housing out with oil and found machining debris. My guess is they are not properly cleaning out the turbos.
I also noticed that with the oil supply line that was provided. The -4 fitting that threads into the OFH was not drilled out. So if people do not notice that before installing, the turbo would never receive oil.

 

[prove_it]

Yikes! Yea, they are cheaper for a reason. If you know what your doing and looking for, they can function fine.

 

[EHmotorsports]

yeah I did it more for testing and fun.

 

[prove_it]

What boost levels? Which turbo and company please?