Just now getting close to done on a 6 liter swap with a VSR Next Gen 78/75. I have started the engine and the oil pressure seems a little low at around 30psi idle. I installed a high pressure Melling oil pump while I did the cam swap. I have heard of guys using oil restrictors to the turbo, but don't know if that is standard or just depends on combo. I am new to this whole deal. What do you guys think, should I be using a restrictor to the turbo?

 

On a half dozen or so cars with turbos, all factory, I've never seen a turbo without a restrictor in the supply that didn't over-oil the turbo. just my limited experience. Hoping someone else chimes in. I have seen where if you have a dry-sump stage semi dedicated to the turbo drain its pretty tough to over oil.

 

NO! never use a restrictor on a journal bearing turbo! ESP if you have lowish oil pressure! The only turbos that require restrictors are ball bearing units. And maybe systems with abnormally high oil pressures like 60-70 idle and 100+ WOT. The cartridge has orifices in it that restrict the turbo the proper amount. If you have smoking issues your drain or Evac system is setup poorly. Use a proper 3/4 ID drain made of metal tubing of some sort and -4 feed with a proper drain angle. Don't use a bunch of AN fittings with tiny ID and you'll never have an issue.

 

If you can't fit a large enough return line then you NEED a restrictor or you'll just blow oil out the seals. Not everyone can run a sewer line for a return.

 

lol. We can agree to disagree.

X amount of oil should flow through a turbo a minute per the manufacturer, period. Trying to redesign and limit the flow rate around a poor drain is working backwards and will shorten the turbo life... possibly drastically, possibly not.

It's a critical part on the installation either way. If you don't have room for a WG do you try to limit your boost control with a 1" exhaust pipe? No, you make room where its needed. Don't half *** a drain as you're likely to break something. A 3/4 hard line is no larger than a -10 braided SS line. It's also more heat resistant. Laziness is the #1 reason for poor drains IMO. It's not expensive to do it right. I'm a corner cutting ****... this is one of the few things I won't skimp on! 160mph in a janky $2000 bent up chasiss with 1978 suspension and brakes... eh... not a big deal. my drains gonna be nice and clear!

Also don't get the "blowing the seal" thing. What seal are people talking about? Therese the equivalent of little steel piston ring on the shaft. If the oil all drains out gravity wise it seals great. id it backs up in the CHRA it leaks past. Ive never experienced or seen a "blown seal" Once the drain issue has been addressed. The problem was always gone as well in my experience. "BLOWN OIL SEALS" are a myth as far as I can tell.

 

I prefer to go off of experience instead of the theoretical when it comes to feeding journal bearing turbos. I've had restrictors on journal bearing turbos for years and years without a failure on more than 1 car.

Seals are exactly what you said they are. They're rings that if they aren't clearanced properly or have too much oil stuck in the turbo, it gets past the rings. Except nobody calls them "turbo rings", they refer to them as seals. My daily driver had to have the 2 turbos replaced under warranty because they claimed there was a defect of the turbo seals lol.

 

If you want to put this to rest, just contact Viren at vsr. I can tell you what he told me though on 2/21/20 in an email reply back. He said to use a .060 restricter with HV/HP pumps.
30psi hot idle is perfect. My 2019 silverado has about that at idle. SO does my turbo gto. Ive been having a restrictor in mine for 2 years and Ive put about 10K miles on it. -10AN drainback.

 

I love how back yard experience or a china turbo vendor "puts this to rest". Did Viren engineer or design any of the turbos he sells? Does his china dealer provide a factory repair manual with all the oil flow specs and compressor maps?

Sure you can call a random vendor of china turbos and take his word. Or you could possibly say... look at a turbo manufacturer's that have been around 100 years and maybe take their word for it? Garrett, Precision, Airwerks, Borg, Holset, etc... All of them clearly state journal bearing turbos should not need a restrictor if the oil pressure is within spec and not overrunning the bearings. Which 30 psi sure as heck isn't doing. They also clearly say bigger the better on the drain but at least as large as the drain diameter itself all the way through with the proper gravity drain angle.

There are no arguments here. If you haven't measured the volume of oil coming out of your drain at idle and compared it to a factory turbo manual, then you're just back yard engineering and guessing to your best ability. Nothing wrong with that really, but it doesn't make what your doing correct. Who's to say how many miles you may be reducing your service life to. Who's to say a .80 restrictor restrictor on his turbo might not shorten its lifespan by half? Why would you take the risk?

 

not sure if you read my post. I didn�t say my 2 years of driving it problem free would put it to rest. Asking the supplier of the turbo would put it to rest. If you want to GROSSLY OVERTHINK this, then be my guest. I think what you just posted is comical, it�s a $500 turbo for Pete�s sake. And my back yard engineering may not be as over complicated for nothing like you are posting, but it works. You probably don�t check half the shot you say you do. If you really disconnect the line and measure the flow, you have way too much time on your hands. Do you do it at different temperatures too, oil gets thinner with temp.

you do you. I�ll do me, which seems to be the popular opinion in these threads anyways. I�m pretty sure you know more about virens turbos than he does. Lmao.

and you are trying to compare a China turbos info to holder, Borg etc.....which makes no sense to me. (Shrug)

 

Does ANY china turbo MFR supply a compressor map, including VSR? Not that I've seen. Is a compressor map relevant to oil restrictors, nope.

Whose talking about 30 psi? Most people have issues with oil getting past the turbo seal rings at WOT. Try 2-3x that pressure. Decelleration is also an issue because the drain backs up due to g force pushing oil to the front of the pan.

I'm a rear mount turbo.....I HAD to verify volume of oil coming out of the turbo lol. It's completely true that there is no exact way to tell how many miles we're shortening turbo life by adding a restrictor, just like there's no way for you to know for certain how many miles you're extending the turbo life by removing the restrictor lol. That logic goes both ways. My turbo wasn't even $500....it was half that If you're spending the money on a $XXXX.XX turbo, you're not coming to this forum to ask about oil restrictors anyways.

Just FYI, The stock Fbody T56 is rated to what, 400 or 450hp? People run double that and it doesn't blow up. It reduces the life of the transmission, and no one can say if it'll last 5 miles or 50,000 miles.....better put out an PBS broadcast that they're using the transmission wrong.

 

The OP that we are trying to help is talking 30psi, the one asking about using a restrictor. And to him I still say no, absolutely not needed.

Its not overthinking it IMO. Its such a great and simple design, yet people treat them poorly and then blame the turbo. It's pretty simple to keep them happy, even the china cheapies, yet people still have to screw with them.

Correct, no china manufacturer or vendor is supplying us with this information, because it doesn't exist. So why take a vendors word about an oil restrictor? The china casts/molds and designs are pirated from the big name manufacturers. So its pretty simple reasoning that they would follow the same general rule guidelines.

I work on turbine engines by trade. They are amazing and very simple things, much like a turbo. The 1 thing you really have to do is get the oil flow through the bearings and make sure it's clean. That's basically it and the things will run 30,000 hours straight. So when the turbo engineer states it needs X amount of oil through the CHRA to keep the film strength up and keep the thrust properly lubricated/cooled, there's a reason for that. Arbitrarily throwing a restrictor on because of a poor drain is done all the time here. It's why i default to "NO" when people ask. I didn't call your specific setup as wrong. Look at the #2 response... it's just plain wrong. And for someone new to the turbo world thats the kind of information that can damage someones turbo.

Comparing under-oiling a bearing to the hard parts of a transmission isn't exactly and apples to apples comparison. How about you throw a restrictor on your engine oil pump outlet reducing the outlet size by 30%. Your engine bearings won't instantly self destruct... But its not a good idea in general.

 

Maybe you're misunderstanding my comment about oil PSI. The OP doesn't have 30 psi of oil pressure at WOT. He has it at idle and is asking if his lack of having an oil restrictor is causing his ENGINE to have low oil pressure, like the turbo is somehow changing his ENGINE oil pressure. Obviously this isn't the cause of his low engine oil pressure......then we all jumped on the restrictor vs. no restrictor debate

As far as background, yours does explain why you're **** about oil flow and not using a restrictor lol. I have USPTO submittals in the area of turbo's myself and work in the transportation industry with 30 or more patents around the world. My specialty is closed loop failsafe control systems. Nice to meet you (are we virtually sitting in chairs in a circle drinking coffee talking about our gearhead addictions??)

 

Well, that clears things up. I am using a -4 feed and a -10 drain with a good flow path back to the pan. The 30psi observed was at cold idle. The readings seemed a little inconsistent, so I replaced the oil press. sender. I have not had the engine running since the new sender was installed. I should have everything wrapped up in a couple of weeks and can check things out then. I think I will start off with no restrictor and go from there. I do appreciate all the input.

 

Well I didn't think that the turbo was changing the oil pressure. My thought was that if not having a restrictor before the turbo was similar to just bleeding off part of the oil supply into a bucket. I don't know enough about turbos to know if the oil is pressurized until it makes it past the bearings or if the oil drip lubes them or whatever. Learning more every day.

 

This makes it sound exactly like you thought the turbo was bleeding off your engine oil pressure. But like you said, learning more all the time. Glad your setup is up and running.

 

You're right, it does sound like I thought the turbo was the cause. I meant to convey that I thought it was the lack of having a restrictor that was the real culprit and was trying to figure out if every turbo required a restrictor. Now I'M confused

 

 

I love this guy. No homo.

 

lol

 

I�d like to add. Viren sells turbos. And lots of them. I�m sure he gets lots of feedback from people. If he says run a restrictor on his turbo, then I have no reason to not trust his advice. Especially since it�s had a restrictor since day 1. It was larger at .090 like Matt Happel recommends but I changed it when I put the new motor in per virens recommendation. If this turbo lays 50k miles, I�d be ecstatic. I�ll probably be upgrading before then anyways.