MFSPSTurbo

The fittings we supply are not unique, or new, or exclusive to any race shop. Do we custom-machine certain fittings to make things easier? Yes, we do, but there are versions of what we offer already available, if care is taken to make sure the requirements for dimension are met. Literally thousands of EFR Series units are installed without any issues, but when problems are identified, and they are rooted in a deviation from the engineered requirements, sometimes customized parts are required.

The same requirements for turbocharger oil return have existed for decades for every turbo that uses gravity drain systems. The same rules apply, regardless of what manufacturer's turbocharger is being used.

Basically, the goal here is to get oil out of the turbocharger and back into the sump as rapidly as it's introduced into the turbo, so that it isn't forced out of the sealing structure due to a differential of pressure. Since that oil is being churned into a foamy mixture due to the operation of the bearing structure, the oil drain port is significantly larger than the supply port. So the requirement for that drain path is also larger than the supply path.

This is an aspect of forced induction fabrication that is often overlooked, but it goes back much further than any new turbo design. If it means anything to you (and it may not), the same tubular oil outlet assemblies we make for the EFR Series are also sold and used for the HTT/Garrett GT and GTX series on a regular basis. We actually started providing those tubular assemblies back in the late 1990's when the Garrett T25/T28 units were popular for use on the Miata applications, and since the EFR Series uses the same bolt pattern, it was natural to use them for the later designs.

We didn't invent or re-invent anything; we're just trying to provide effective solutions to existing problems. BorgWarner didn't invent or re-invent the basic engineering requirements for oil plumbing, but they do publish those requirements, and we strongly suggest following them for best results.

There are off-the-shelf parts that work very well, for sure, and when and if those off-the-shelf solutions provide an effective solution, we stock and sell them. In the case of the EFR, we offer many solutions, and some are better for certain applications than others.

I think the key takeaway here is that it's been somewhat common to use anecdotal information, hands-on experience, and what we like to call 'tribal lore', to influence design and application decisions, and sometimes, well, those decisions aren't always correct.

No finger-pointing, no blame, just suggestions for best-practice, are what we're trying to offer here.

sixshooter

iTrader: (12)

What is the bore of the bearing housing?

What is the minimum drain diameter specification?

Is there any conceivable problem with the turbo being mounted with the compressor end slightly higher than the turbine end?

Thanks for your interest in helping, Mike. We appreciate it.

MFSPSTurbo

I believe the support document we supply was uploaded somewhere in this forum post, but if someone can assist me in doing so, I have it available in both Word and PDF formats. Either can be emailed as well.

There is also a very large .pdf available on the BorgWarner website, available for download, which is called the "EFR Technical Training Book", and it's a good read, although it has not been updated since the program debuted in 2010. I keep a bound copy on my desk at all times, and even after 9 years of working with this product line (we came into the program long before production), I still refer to it regularly.

Doing a little "copy-pasta", here's the basic information, though:

· The oil drain is machined with a 9/16” (0.5625”) bore, then tapped for 3/8”NPT. The threaded feature should ONLY be used for engines using a scavenge-pump drain system, as any fitting threaded into that bore will introduce an immediate, unacceptable static drain restriction. For gravity-drain systems, it’s critical that the bore in the bearing housing is the smallest diameter in the entire drain system, from turbo to sump. If –AN-style oil drain systems are used, care must be taken to ensure that adaptor fittings are not restrictive in any way.

If anyone needs assistance understanding how -AN fittings are sized, I have some experience in that area as well. Ultimately, though, the AN "number" always refers to the i.d. of the hose itself, and the i.d. of any fitting that fits inside that hose will naturally be smaller than the hose, which is why we suggest taking the time to confirm sizes prior to use.

I've actually heard the former technical support engineer at BorgWarner (who works for our company now) describe how they used to qualify oil drain systems at the O.E. level, and I'll paraphrase below:

"We would take a marble or ball bearing of the specified diameter and drop it through the top of the oil drain flange, and the expectation was that it would emerge from the lowest connection point of the oil drain system without restriction"

(Obviously, with the drain structure removed from the engine)

I have heard this same basic story repeated during my time working in the BorgWarner booths at SEMA and PRI for the last ten years so many times that it's forever stuck in my mind.

Seems simple, right?

freedomgli

Thanks! I really appreciate you taking the time to share your expertise.

sixshooter

iTrader: (12)

So 9/16 absolute minimum diameter? Got it. Thanks.

Ryan_G

iTrader: (8)

The problem I am having with this turbo is that it is still pressing oil out of the intake side even with a 3/4" hose off the flange drain outlet I bought from SE Power Systems which then feeds to straight 1/2 NPT to 3/4" hose barb fitting in the pan. The 3/4" hose barb measure 0.6XX" ID with my calipers. My breathing system consists of two massive 5/8" lines running off my valve cover which are supplied by 2x 1/2 NPT fittings. I have drilled out the small vent hole inside the baffle of the oil vapor passage in the valve cover as well. The lines terminate in a catch-can that is VTA. Sixshooter runs the exact same breathing system without issue. Last time my compression was checked while dealing with this problem it was strong. The turbo was serviced by SE under warranty and checked out completely fine as well. Something, however, is wrong and I cannot for the life of me pinpoint it. I was going to try and use a 1.6mm restrictor since I see that this product is being sold in the UK for this exact issue with EFR turbos. Just before I got to try it my car decided it wanted to not start now so I haven't been able to test it.

Mike, the one question you didn't really answer was whether a slight angle on the turbo with the compressor sitting barely higher than the exhaust housing may cause an issue with the oil drain even if the drain is pointing straight down. I would think this would press oil out of the exhaust side instead of the intake side though but maybe the pressure differential is bigger on the intake side.

Art

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Marvin

This is all excellent information. I'm in the process of working out my drain design for my 6758 and I stumbled across this thread at what seems to be an opportune time. One question/note for the masses, I've downloaded the EFR Turbocharger Technical Training Guide from BW dated 2010 and where it references oil drain setups, it makes no mention of scavenge systems defining the requirement to use the 3/8" NPT fitting. The way I read the document, is that 1/2" ID is sufficient all around and -8AN is the minimum spec. Thus, a 1/2" NPT fitting to -10AN like Trackspeed's solution is more than capable of avoiding oil blowby assuming the turbo is mounted level. Again, crankcase pressures notwithstanding.

"The bearing housing oil drain is machined for two connection types. The oil drain port is tapped with 3/8-NPT threads for those who want to install a fitting. A fitting with 3/8-NPT on one end and -8AN on the other makes for a very nice solution. The through-bore of such a fitting is about 0.42”, which then spills into a 0.5” ID drain line. For those wanting to install a gasketed flange, two M8 holes are provided with a centerline span of 1.5”" (Page 39.)

"The oil drain flange on the bearing housing has been prepared for either a paper-type flange gasket (the bolt spread is 38mm or 1.5” and the bolts are M8x1.25) or a screw-in fitting. If the port thread is selected, a fitting with a 3/8-NPTF tapered thread should be used. We recommend the white liquid type of sealant instead of Teflon tape. The oil drain line should be at least -8AN (1/2” ID). The bearing housing oil drain should be pointed straight downward where possible, and at most 20 degrees tilted right or left. When routing the oil drain line, try to keep it running downhill all the time and avoid horizontal spots or sharp bends. The oil should drain to the block or pan in a low-pressure region above the level of the oil bath. It is not recommended to install the turbo considerably nose-up or nose-down. It was validation tested to be installed “flat” with respect to the ground." (Page 74)

Marvin

Small clarification to the above statement, the reference document is the EFR Turbocharger Technical Training Book, not guide, which is approximately 8.5mb total and what I assume to be the source referenced above. Second, TSE's kit is supplied with a -10AN to 3/8" NPT fitting, however, -10AN to 1/2" NPT fittings can easily be sourced for the oil pan side of the drain for something like $6, which is what I intend to do to avoid the internal step down in the aluminum fittings from -10AN to 3/8" as described by the measurements in the original post.

Bronson M

iTrader: (1)

I've been able to find a 3/8" pipe thread nipple with a full 5/8" ID, just have to look fir them or drill then out.

nbfather

Precision makes a great drag race turbo, but they have no idea how to make a reliable street turbo or track turbo.
Any Precision driven on the street is likely to start smoking like a dirty barbecue before long because of what (I think) are undersized seals/bearings.
2 different twin sets and each time Precision found a way not to look after me.
Each time both turbos were smoking badly.

My last (3th set) were a pair of 7675 CEAs...I had both draining via 5/8 tubes into an atmospheric vented reservoir, which was emptied via dry sump....
The rep came by and looked at my setup, could find no fault...and covered those turbo....When I got them back I sold them.

Just so you know what you are up against.

Art

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sixshooter

iTrader: (12)

This is a case where going much larger than spec can never hurt.

2manyhobyz

iTrader: (4)

I would recommend more be done with the scavenge side of the system. Trying to achieve negative atmospheric in the crankcase under boost makes a lot of sense. I was thinking of a really low pressure sensor that could read about 2 psi to 5 inches of vacuum. Mount it in an extra oil filler cap. 0 - 5v reference and then you could run a log and see if improvements can be made to scavenge the system better.

Bronson M

iTrader: (1)

When are you guys going to quit screwing around and go dry sump? I hear 15 in/hg if vaccum is no problem. Fixes that pesky oil pump gear problem too.

2manyhobyz

iTrader: (4)

Do you run a dry sump??
I think for most of us the payoff isn't there. I'm sure we can come up with a more cost effective solution. First step would be to monitor/measure the pressure/vacuum we are experiencing. If I recall, I think it was VW or Mercedes that had an electric motor for this.

Bronson M

iTrader: (1)

Sarcasm must not have come through, No I don't run dry sump......yet. I kinda dropped that out there to keep a sanity check on any solution you might come up with. Once you consider the cost of a boundary pump and whatever crazy contraption you come up with to solve the crankcase pressure issue you might not be too far off of a 600$ 3 stage pump and another 300 to 400$ in lines and brackets.

2manyhobyz

iTrader: (4)

Yep, I need to be constantly reminded to turn off the sarcasm filter.
I'm more interested in finding a low pressure sensor to use as a temporary diagnostic tool to see if a little internal engine pressure effects the turbo drain line and creates the aforementioned oil seal blow by.

aidandj

iTrader: (5)

Try a map sensor. That's what I have for logging crankcase pressure.

2manyhobyz

iTrader: (4)

Thanks, that seems like a great solution.