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.

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).

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.

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.

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.

wrong thread.

roger that about blowing up the motor. At this point I just want to see the turbo get oil and be able to spool up to check for boost. I do have the entire turbo FI setup so eventually the plan is to outfit the the test stand with that setup for testing. I will have to dig into it to see if there is any missing parts, it looks pretty complete. I forgot to add the color tune plug, I really want to better understand how that O2 sensor readings relate to actual combustion, I trust my eyes to read the color tune.

I used the cheap poorly rated amazon kit, worked just fine. I can only assume the neg reviews were by folks that do not know how to use a tap. It took a while to ream and tap but nothing extraordinary. I ended up using a punch to stake the insert since there is no mechanical lock and I did not use any thread lock (I cant imagine it working in the high heat of a turbo down pipe. did another video of the engine running this time using the narrow band 02 sensor hooked to a analog voltmeter. I think I am about done testing without the turbo, so that will be added soon. Will use the NA fuel injection and closely monitor the air fuel mix to keep from running lean. Added a variable resistor to the temp sensor to allow for added enrichment.

have not tried that. Its a really old hobby lathe, no auto feed etc. Good for small stuff. I think for now I may just use a big washer to capture the top of the O2 sensor hex and then drill some matching holes that can be used to bolt the wash down to the flange where the heat shield use to go to retain. Not a perm solution but good enough for now. I may try one of those cheapo kits, like you said good for one try prob. I have been thinking (dangerous) about adding closed loop to the existing NA FI. Use a voltage divider to arrive at a .5v bias (maybe get fancy with a zener diode), use that and the output from the single wire O2 sensor to arrive at a 0v difference when AF ration is correct (.5v out from the sensor). Feed that in series with the wiper of the AFM, smoke the computer or have a a closed loop FI. any bets which it is?

You have to be very careful about all the little plastic bushings/washer placement. I goofed on and ended up blowing fuses when activating the washer button

O2 Oxygen Sensor Stepped Weld Bungs (5 Bungs/5 Plugs) M18 x 1.5 | eBay maybe just weld on some mount ears and use something like this. I have not done much drilling into cast iron, maybe that is the expensive trick, tools hard enough to deal with heat cycled cast iron?

Geez louise, I need to repair the 02 sensor hole on the cast iron down pipe from the turbo. Its hopelessly stripped (not enough left to chase). So I figure heli coil etc... BIG bucks I mean like cheap o kit 100$ good stuff 200+. Perhaps its the hard iron that needs some really good taps to work with? there are some cheap kits on amazon for as low as 35$ but they all have terrible reviews. Took it to a machine shop was told 130$. So if any of you guys have some exp with how to fix cast iron O2 sensor hole, please speak up. I have another possible solution, the hole is set in a cast in flange area that had a heat shield bolted to the cast iron. I am pretty sure I can turn a alum piece that woutl fit over the 02 hex and then I could capture the sensor that way. I just can see spending 130$ for what seem like a simple tap and time sert job.

did you take the multi switch apart to clean it?

Ok tested again today, this time with the plugs torque to spec, again passed with flying blue colors. Only thing I can think of is something in the coolant that had to boil off. Perhaps all that WD40 I used (filled it with the stuff then drained it out to prevent rust after rinsing the evaporust out. Maybe there was trace amounts still in there? I guess as a test I could simply dump some WD 40 back in and see if the test for gas comes back positive again. Or I could move on to the turbo install. With the 02 sensor I am able to monitor the Air/fuel ratio pretty well. I could just keep an eye on that and try it with boost on the NA setup. I did test the color change by sampling the exhaust from the muffler, turned yellow right away.

I dont know for sure, but I think it will detect C02 from and I presume C0 as well.

ah, a variable... whilie I was putting the engine away for the day I recalled my plan to look in the cylinders (before doing the last chem test that was a win. My plan had been to inspect for dye in there, in prep for that I had only installed the plugs finger tight to briefly run the engine to circulate the dye. SO, is it possible that some of the exhaust pressure was leaking past a less the fully tighten plug, thereby reducing the combustion chamber pressure enough to allow for the test to pass? Its at least something to go on. Its too late for me to run the engine now, but will make sure the plugs are torqued to spec an will try again tomorrow. Geez I hope is passes, but if not at least the puzzle will be solved. And if it does fail I think I will try running while disabling one cylinder at a time (pull the fuel injector connector off). That should allow me to narrow down the issue. I actually started down the path earlier before running it in the video. I had removed #6 plug, thinking it would lessen the load on the engine to not have to compress just the air, well silly me, engine ran like crap, massive air leak I guess, so I reinstalled the plug (hand tight) and the video was made. Now to be clear the plugs were not loose, fully seated, and I could not detect any odd noises while running making the video, Just snugged up with to the washer.

I wish I knew, only thing I did was add the uv dye to the system. Clearly I will be retesting, I am using the fluid from the same bottle, I should have sniffed from the tail pipe to confirm color change, will do that next time. I will conduct more test over the coming days. Thing is IIRC I had the same thing happen on the N42/MN47 spare engine, failed at 1st then tested fine later and ever since. REALLY bugs me but if I can't get it to fail again (and remember it never overheated when it did indicate fail) then I will take the W, don't want to look a gift horse in the mouth.

hmmm

leaking oil is a good thing when it sprays the underside of the car, keeping rust away. Check those hubcaps often, they have a way of getting loose and a hard turn or pothole will send them off to hubcap heaven, never to be seen again.

going to try adding some UV coolant dye to the rad, pump it up with a pressure tester, let it sit for a long while, then spin with plugs out and see if any dye is expelled thru plug holes. I tried already with pressure and then examine with borescope, but its not the best and could not really see well enough to call it. I figure the compression stroke will aerosol any accumulated coolant and spray will show the dye. I will spin the engine with the plugs out to hopefully disburse the dye, that may not do it though.

here is the water overflow test. Note I did the same test with my car that does NOT change the fluid color, and I had the same results, water started to over flow within the same time span as this video. So as CO mentioned, the water apparently was expanding enough to start flowing with out the introduction of gases (in my good engine in the car).

chem test

roger that CO. well I will have the videos soon, both of the water expansion and the chem test. Not looking good... let you guys have a look. tell me what you think. will post here soon.

leak down test done, passed with ony about 5-8% max loss. I suspect the combustion pressures are way higher so doubt I could pick up on a small leak. I am going to try the top off with water test again. seems like NO water should flow out of the rad top on a cold start for at least a few min. IF any comes out at all then it seems must be gases displacing water. I figure it must be done cold to avoid any trapped air in the water jacket heating up. I assume IF no air at all in the water jacket, NOTHING should overflow as I dont think water expands from heat, at least until it shifts into steam.