Hi all. Rebuilding a Series 5 turbo due to shaft play. I have everything apart and everything looks fine inside.

It came with these aftermarket AN adapters:





Is this oil orifice appropriately sized? Is there even supposed to be a restrictor in this system? I don't have the factory lines to compare.

Also while I'm on the topic, once the bearings are out can I just drop the CHRA in degreaser for awhile?



As far as I see it's just one piece of cast iron, so it should be fine. But I've never done this before.

Thanks, Chris

 

hmm the factory setup doesn't have any restriction on the oil line, its just the pipe right into the turbo.

you can dunk the center section into something after all the bearings are out, its just a piece of iron

 

^What he said, the OEM oil line is just a pipe without any restrictions built into it. Is this a stock OEM rebuild, or is it BNR or other modified hybrid turbo? Reason I ask is when I switched to a BNR stage 3 turbo on my S5T2, I had to add an oil feed restriction to the plumbing, similar to what you have pictured, to keep my new BNR turbo from smoking. The BNR CHRA's don't have a built-in oil restrictor, but apparently the OEM stock ones either don't need the restriction, or have one built in.

 

Just a stock S5 turbo, nothing special going on.

I'll drill out that fitting to remove the restriction then. I can always make a restrictor later since it isn't a very complicated piece to fab.

 

And while I have you guys here, is there a gasket for the flange that goes between the hot side and the downpipe? I didn't see a gasket when I took it apart, but obviously it's too hot for sealant.

 

Yeah, there should be a metal gasket between the turbo's hot side and down pipe (or precat, for an unmolested OEM US market FC).

 

No, I know about that one.

I'm not sure what the name is for the part, but it's this plate that goes in-between the hotside and the downpipe. It has five holes in it, two bolt to the hotside near the wastegate door and three are for the downpipe studs. I'm wondering if it needs a gasket between the plate and the hotside.

I can take a picture after if I'm not describing it well.

 

Between this guy:




And the hotside.

 

nope, that is just two flat surfaces, no gasket.

 

Okay, sounds good. Thanks to both of you for all your help

 

I keep finding new things to ask here.



Adapter fitting (10AN) compared to the stock drain size. Small difference, but I read online that lots of people are using 10AN drains without any issues.

Then my feed adapter:



I think it's 4AN, not 100% sure. Anyways, even if I drill out the restrictor its way smaller than the stock opening. Is this okay? Does the stock supply line taper causing a bottleneck somewhere else?

Thanks again

 

i think even the stock setup the feed is smaller than the opening on the cartridge. its like 4mm to 6mm or whatever it is

i'd be temped to bevel the return line, 10An is obviously ok, but the transition could be better, probably not worth the time to do

 

I've got one of the same AN blocks to feed the top of my turbo. They are more necessary with a modern ball-bearing turbo.

It all depends on what the bearings need. With journal bearings, like the ones in the stock turbo, more oil, more better. The pump will supply all oil needed. It is with the new ball-bearing turbos that you must have the restriction. Too much oil in ball bearings interferes with their rolling elements as they run tight tolerances at all times and causes the turbo to slow or stress, while too little oil for journal bearings increases the possibility of oil starving the journals as they are a hydrodynamic bearing. Here is a good video for information . Since you are running a stock turbo, the restriction is not needed. I drilled mine out. Be sure to drill it out straight though, as you must ensure that oil still lands on the turbo shaft. Also deburr so that there aren't any weird angles put on the oil flow. Best done on a drill press or lathe. I didn't drill mine out to the full AN internal diameter, I choked it down just a little bit, to get a bit tighter of a flow, but that's just personal preference at that point, it no longer causes any appreciable extra pressure.

 

When I put my car together I used an oil feed line from an oil filter sandwich and 4an line into the turbo. The flange had a very small hole like the one you have pictured. I contacted BNR regarding this for my older Stage 3 turbo and he said it would be fine. I have had the car running about 3000 miles now without issue. The hole was approx 1.5mm on the flange.




Good luck and have fun!

 

I drilled the supply adapter out to the full 4AN size and left the 10AN mostly as-is. I would have bevelled the 10AN fitting but my drill press key is missing and my regular drill can't hold a bit of that size. I ended up just using sandpaper to round out the opening a bit.

I ended up drilling it out to the full size. I used a regular drill (see above as to why), but using some wood as a jig it worked out fine.

If / when I run an aftermarket turbo someday, it shouldn't be too hard to make a restrictor plate. Thank you for the video, it was quite informative

Thank you! The fun is a far way off. I'm trying to get all my ducks in a row to minimize the downtime between taking the car apart and putting it back together. The name of the game is to maximize seat time and minimize "engine parts spread all around the floor of the garage" time.