LeeMajors19082

Okay, this is probably going to be a very noobish question but upon numerous Google, H-T, HondaSociety, and FI/Honda forum searches I've come up completely empty handed, while trying to find an answer to this question... so here goes:

Should the center section of a turbo, between the oil feed/oil return openings, be airtight? And if it's not, does this signify the need for seal replacement? Also is there a way to verify the status of a turbo's seals without applying oil pressure?... In other words, is there a way to test/verify them with the turbo OFF the car?

Thank you for any and all replies in advance

Geis

Sure, just take the engine out.

*assuming you have equipment to do so :p*

wantboost

iTrader: (2)

the seals only "seal" under positive oil pressure. They are piston ring type seals so that is how they operate.

You can't verify seal condition without pressurizing the bearing system as the seals will just let any oil you put in the CHRA seep out over time without pressurization

TheShodan

iTrader: (14)

And it must be oil pressurization. You cannot substitute it with air.

wantboost

iTrader: (2)

Yea I tried simulating pressure one day years ago with a compressed air source, turbo wasn't happy about that lol. Although I did design a rig around the same time that could bench test seal condition using compressed air as a substitute (or one of my Tilton differential pumps) using a stand, oil holding tank with quick release air chuck, feed line, drain line, and so on. Basically it flows oil through the CHRA the exact same way as it would if it were being fed oil from an actual engine.

I need to see if I can find my sketches or reproduce them to the best my memory will allow. Maybe even build one lol

LeeMajors19082

Thank you fellas... this^^^ was exactly what I wanted to know.

And this^^^ is exactly why I asked! lol! I attempted something very similar, with what sounds like very similar results lol! But I'd love to see the rig you built for actually using oil pressure to bench test them!? That'd be phenomenal addition to the workshop Thanks again

LightningTeg

Couldnt you plug the return, fill with oil by hand and pressurize that?

hondur

iTrader: (1)

Please do so! Did I mention you're awesome? Thank you for even considering doing this.

wantboost

iTrader: (2)

The problem with filling the CHRA with oil, sealing it, and then pressurizing it is that more often than not there won't be oil in the passages and bearings. The majority of the internal volume of the CHRA is hollow, the oiling passages themselves are quite small (around 1.2mm in diameter for a typical JB Garrett, BB Garrett reduce down to .8mm at the outer bearing race) and without a constant supply of oil through the feed line they tend to fill with air.

So even though you think you've filled the whole thing with oil what usually happens is surface tension combined with the small feed diameter and bearing to shaft clearances (usually there's .015 between shaft and bearing ID) prevents oil from staying in these areas.

The system I thought up uses a tank where a pressurized air source forces oil through the bearing system at typical operating pressures and drains into a separate container. I had tried to think up a recirculating system but with that kind of pressure at the return line it would likely just back up. I have a few ideas I came up with recently about how a recirculating system might be viable but they only way to know is to build the damn thing.

The main benefit I see to something like this is for an individual or company that handles large volumes of questionable turbochargers. It's very time consuming to tear down and inspect a turbo for a particular failure, especially in regards to seal integrity. A tear down that is usually unwarranted as well since most seal issues don't present with any visual cues from the seals themselves . So if you could actually test seals without teardown it would not only speed up the process but save money as well. Using a series of standard quick release methods you could mount, test, and remove a turbocharger in less than 30 minutes.

I still need to find an easy and consistent method of heating the supply oil as you might not see a seal issue with cold oil. A compressed air nozzle would rotate the assembly to simulate actual use.

This is what happens when my inner engineer comes out lol. I always look at everything and see how I can make it better. That's probably also why my builds take foreve because I hate half-sing, taking shortcuts, and not having things as optimal as possible. Le sigh

LightningTeg

Well you could just simply hook a pump that recircs from a bucket like the guys who make home made "turbo" jet engines

wantboost

iTrader: (2)

To me that's a bit crude. If I were making something quick and dirty for personal used maybe but I'm thinking long term here and the possibility of actually developing it into something marketable. I would post detailed sketches but I don't trust some ****** to not copy it lol. Plus the pump method has a few drawbacks. Although I think given your line of work you could appreciate how clean, simple, and fictional yet elegant my proposed design is.

The main issue being the pump. Depending on the design of the pump it wouldn't have the pressure range to simulate the pressure range seen during engine operation since most are a steady speed pump and don't like voltage changes. If you're using a diaphragm pump it wouldn't have laminar flow or pressure to begin with. The nice thing about using an air source is the airflow would be almost totally steady and you would have rock solid control over pressure levels and you could very easily replicate sudden spikes in pressure seen during normal operation.

The other thing is heating the oil. The jet engine pump method works because there's a heat source. Testing a turbocharger in this way on a stand with cold oil might not show issues due to the viscosity of the oil. Being able to heat the oil to operating temp would allow for more through "real world" testing due to the viscosity change at temperature. The easiest way to do this would be using a dry sump tank heating element in my opinion.

The one thing that would also be pretty mandatory in my opinion is an optical tachometer. Just have one mounted on an adjustable arm to compensate for different wheel sizes and cartridge designs and can easily be reconfigured for a different blade count. Last thing one wants to do is over speed a cartridge during testing.

I have the design down fairly solid and much of it can be built using pre-fabricated components. The only things that need to be produced are the physically chassis the rig sits on, mounting points for everything, a simple and well laid out control panel with everything in one spot, and then turbocharger quick mounting/oil line system components. There would be no need to utilize any sort of water cooling for the CHRA since we are only running the CHRA temp up to the low 200F mark which really simplifies the system overall.

Although I guess it would be wise to search and see if anyone has made something similar yet. If not then get the copyright done ASAP then pound out those patent applications. Then at that point it would be building a portable demo model and testing the waters to see if anyone would actually utilize it. Like I said I think the target markets are the smaller turbocharger shops and specialty turbo shops that handle a large number of inspections, rebuilds, and modifications.

Again it would take the inspection process for a "questionable" or "core" turbocharger from a couple hours of teardown and inspection to literally 30 minutes of bench testing without having to do anything other than mount it on the stand, hookup the feed and drain lines, and then run the test. Work smarter, not harder right?

LightningTeg

Let me know if you need any assistance with the CAD. Designing fixtures, tables and carts is a daily project for me.

wantboost

iTrader: (2)

I definitely will. I need to remember where I put my Solidworks 2014 software lol. Haven't used CAD regularly in a while, especially after I stopped working at the machine shop.

I looked up the specs on the brass gear oil pump that would be used "if" it were viable and it flows 3.2gpm at 0psi and is RPM limited to 50-60psi based on oil weight and temperature. So without knowing what it flows at pressure (everyone lists them as scavenge pumps so they don't tell you flow vs psi above 0 since the scavenge system doesn't need pressure) so it might not flow enough. I plan on using this same pump for my remote pre-lube/turbocharger cool down/low oil pressure fail safe system I've planned out for the cars that will sit for long periods of time and will see track days and such but for that application it's perfect.

It would probably be best to incorporate a needle valve on the feed line to fine tune pressure/flow. I'm thinking that there would be the following instruments.

Air supply pressure gauge
CHRA inlet pressure gauge (past the needle valve at the inlet)
Oil temperature gauge
Turbocharger Shaft speed display
Oil feed flow meter (past the needle valve)
On board air regulator to control supply pressure (having one on the unit means you just have to hook up one air line and plug in the heater. It would be entirely self contained)
Turbocharger air "spin up" supply regulator to control shaft speed
Needle valve to fine tune feed pressure/flow
Sight line on the oil tank

Having that all on one panel would make it easy to monitor and adjust things. It could probably be simplified but would require testing first. Given the vast number of turbocharger configurations and their oiling needs on top of the application specific oil pressure range having that much control would make it easy to test a unit for its given application. The biggest benefit I think is the onboard supply regulator. Kind of stupid to hook up an air line and have to walk back and forth to change supply pressure. Put it on casters and you're golden. I think the unit would be too big for a bench system but I guess that depends on the final size and weight. It shouldn't need more than a 1 gallon oil capacity so using minimal fluid saves a bunch of weight. Making the majority of the structure out of aluminum also further reduces weight.

I've been exercising my inner OCD/perfectionist engineer demon come out to play lately if you hadn't noticed.