1st start with rebuilt turbo

[Dave WM]

I got the turbo on, but did not hook up the intake or outlet of the compressor. I check for oil flow by spinning the engine with the plugs out, seemed like quite a bit of oil came out from the bottom port on the turbo. I was concerned that it may starve the top of the engine (cam shaft) of oil so I pulled the valve cover to confrim oil was still flowing from the cam lobes (it was).

So the moment of truth, it started right up (should as nothing changed but the added exhaust manifold and turbo). BUT there seemed to be a ton of smoke coming from the exhaust pipe, oil  burning smoke. Since the engine did not smoke before the turbo I have to assume its oil from the turbo. I wonder if all that oil getting pumped into it is somehow getting past the bush/bearing and burning. Its the only thing I can think of.

Also, the turbo will not spin unless I rev it up quite a bit, its pretty stiff, smooth but stiff. The rebuilder warned me of this (so I would not be concerned I suppose) that due to the type of seals used (carbon IIRC) the turbo will require some time running before it loosens up. Anyone have exp with this?

Lastly I am using the OE oiling system, but the rebuilt turbo did NOT have the same type of fitting for oil in. The rebuilder supplied a fitting that bolts to the turbo and adapts to the banjo bolt. I did not look closely at the orig turbo fitting to see if there was any kind of restriction on the hole size. As is my turbo is getting a straight shot of oil thru a hole that is about 1/8" (the dia of the hole in the bottom of the banjo bolt. 

Anyway I will be conducting some more test to see if the turbo frees up. I still have to work on getting the charge pipe installed, but I just wanted to try it out as is. 

[Dave WM]

Update, ran it again, this time MUCH less smoke, same as before turbo. Impeller starting to spool easier, so perhaps there is something to the "breaking in" of the carbon seal. It still will not spool at idle but will at about 1.5k (estimated based on sound). I will run it a few more times (have to limit runs due to noise in the hood, dont want to po neabours) NA then will see about attaching the charge pipe to see if I am generating any boost. Temps look good (180f with the box fan on the front helping, its mucho hot here in the garage). Oil pressure like what you would expect, low at idle but still slinging off cams, power up and raise quickly to about mid point on the gauge (which iirc is a 140psi, not the 90psi). 

I will get some videos of the setup tomorrow. Hope you guys enjoyed my Nick Saban like rant I posted up a while ago... College football will be cranking up again soon, yea! roll tide!!

one more thing still negative for exhaust gas in rad, had to check of course.

 

Edited August 18, 2022 by Dave WM

[Dave WM]

hooked up the charge pipe, then the AFM to the inlet of the turbo. Monitor the vacuum. I can see NO boost regardless of how much I throttle up. prob reving past 4K which is kinda scary on the test stand. Turbo is still fairly stiff to turn by hand, def can not finger spin it, not sure if that is normal. My vacuum just goes from 20inhg to 0 as I throttle up. From what I have read you need to a load on the engine to generate the kind of exhaust needed to really spool up to boost levels. I am thinking of pulling the turbo off and taking it back to the rebuilder to ask them to check it out and see how tight is. They told me it would be tight due to the carbon seal, but I thought they said it would loosen up. I prob have about 20 min for idle and reving up on the stand with it installed. I did get a new muffler as the junk one I had was small, the new one fits the down pipe (2.5"), so I know its not an exaust restriction. The engine seem to be running fine perhaps the only way to know for sure is to pull the trigger and install it....

Come on you turbo guys give me some advice about this lack of boost on the test stand situation.

[BoldUlysses]

Yes you need a load on the engine to generate boost.  All the turbo cars I've owned/driven didn't develop boost until well into 2nd gear on the road.  Also the compressor wheel / turbine spun freely by hand.

If all you need to do to get it on the road is to reassemble the intake, why not test drive it?

Edited August 19, 2022 by BoldUlysses

[Dave WM]

being new to turbos I wanted to get some time with it on the stand. I see a lot of comments about it needing to be loaded to generate enough heat energy to actually spool to compression speeds. If def does NOT spin freely by hand, but the turbo rebuilder said that is normal for a carbon seal, and that it would get better with use. I can turn it by hand but not "spin". Perhaps its a matter of terminology, the impeller turns smoothly just not easy. It getting plenty of oil, I pressurized the system with the return line off to make sure oil was getting thru it. when I rev the engine up I am seeing about 40-60 psi (lower at idle of course). 

I am coming around to the conclusion that as you mentioned a road test it prob the best way to find out if its going to work. My plan was to use the existing EFI and just add the turbo and manifold to add boost. I assume the stock EFI can handle it, esp if I take it easy and dont get on it too hard (assuming the boost comes up that is).

[BoldUlysses]

What model/year Z do you have?  Not sure about the stock fuel system being able to handle it; you almost always need to add fuel when adding a turbo, otherwise you risk running lean under boost and grenading your engine.

[Dave WM]

its a 75 280z. I was thinking of adding a rheostat to the water temp circuit, add resistance to mimic a cold engine. 

[Dave WM]

 

[BoldUlysses]

Quite the getup you have there.  Do you have a wideband O2 sensor and EGT gauge?  Those are going to be very helpful to ensure you're not running lean under boost.

Still not sure about the turbo.  I can imagine it would be stiff when you got it back from the rebuilder b/c of the assembly lube, but that should be flushed out the first time oil pressure comes up...

[Captain Obvious]

Could you put the stock intake snout back on and run the engine like that? In other words... Run the intake tract in NA mode and pull the turbo intake stuff off, but leave the turbo installed. I'm thinking that with the turbo in place you could look inside it while the engine is running to see if the impeller is spinning at all?

I'm no turbo expert, but your description of how much force is required to spin it has me concerned.

[Dave WM]

On 8/19/2022 at 8:58 PM, BoldUlysses said:

Quite the getup you have there.  Do you have a wideband O2 sensor and EGT gauge?  Those are going to be very helpful to ensure you're not running lean under boost.

Still not sure about the turbo.  I can imagine it would be stiff when you got it back from the rebuilder b/c of the assembly lube, but that should be flushed out the first time oil pressure comes up...

I have a narrow band O2 that I was monitoring with a voltmeter, I was adjusting the temp sensor to try and keep the voltage right around .5v

do not have an EGT gauge, did not know about that will look and see what I can find.

[Dave WM]

On 8/19/2022 at 9:40 PM, Captain Obvious said:

Could you put the stock intake snout back on and run the engine like that? In other words... Run the intake tract in NA mode and pull the turbo intake stuff off, but leave the turbo installed. I'm thinking that with the turbo in place you could look inside it while the engine is running to see if the impeller is spinning at all?

I'm no turbo expert, but your description of how much force is required to spin it has me concerned.

will shoot a video of the naked turbine soon it will spin on its own once you get a bit over idle, just not fast enough to generate any real airflow from the compressor side.