'94 E34 Touring slicktop, forged M50B30 powered, S362SX-E boosted, daily driven

[Dj Buttchug]

Nice progress. Not sure if my issue is comparable but your smoking symptoms seem somewhat similar to mine. Oil in the combustion chamber obviously rules out turbo oiling issues.
I have been battling this issue on my engine as well for the past two to three months with several changes in the turbo oiling system and no success in fixing until this weekend. I am pulling oil from the oil plug at the rear of the cylinder head. I don't believe the location of the oil feed is relevant, but pressure and flow could be different if you are pulling from the filter housing or another location close to the oil pump. Anyway, here what I've been dealing with.

At engine idle, low load or lower RPM rev range there is no smoke in the exhaust. But as engine speed and oil pressure increases things change. If I enter the 5k + engine speed range or quicky stab the throttle and let off, engine goes into overrun (no smoke yet) Right when we reach idle speed again, I get a lovely sizeable puff of bluish smoke. It would happen every time. My engine doesnt smoke on startup only coming off rev.

There was no evidence of oil in the turbine housing at all. No wetness or dark markings. Nothing.

My old oiling system was as follows. -4AN line to a standard oil restrictor that came with my turbo. I believe the hole sizing was .065 or larger. This caught my eye but I installed it anyways. Still no changes in smoking after moving from a journal bearing turbo to a BB unit.

To fix the issue I ended up switching to a -3AN line, .035 restrictor AND creating a restrictor at the port on the back of the cylinder head. I Tig welded the M10x1.0 shut on the cylinder head side and redrilled the inner diameter smaller to reduce overall volume in the line. After doing this I tested to confirm the turbo is still getting sufficient oil flow through a clear temporary drain tube. After I did this mod, the smoke is gone. I can bounce the engine off redline and it still will not smoke.

My car is still in the air, so I have not yet been able to test on the road, but I think reducing the amount of oil in the line has fixed the problem. My theory is the volume of oil being delivered to the CHRA is too high (even when properly restricted) and was just enough to spill over into the exhaust turbine... ??? Hard to know for sure. I should also note I did have a small bit of oil in my compressor housing as well (very light film that would creep from the compressor blades) This symptom is now gone as well.

I should mention as well that I tried 4 different oil drain setups, modified the drain tube inner diameter to make sure oil could escape the center cartridge quickly and tested several settings of CHRA clocking trying to find the best setup for oil flow. I ended up using a magnetic level to ensure my turbo is clocked correctly. Being you are top mount I think there is less need for this but worth adding for info purposes.


Hope you get it figured out and looking forward to how the new turbo spools up.

[varg]

I've been daily driving the car for a while now and have about 1,300mi on the engine. The smoking issue is bothering me, new valve seals didn't fix it. I replaced them after spotting a drop of oil running down a cylinder wall and oil on the combustion chamber and valves while borescoping. I noted nothing wrong with the seals I removed and it proved to be a total waste of time replacing them. I've performed leakdown test but unfortunately my old harbor freight leakdown tester has poor resolution because of its oversized orifice so all it told me was that all cylinders are the same within its resolution. Currently I'm unsure of what I will do about this because it's hard to gauge the oil consumption. My valve cover leaks persistently, having been ruined by an incompetent powdercoat shop, it does not seal even with RTV on both sides of the valve cover gasket and leaks at the fill cap. I'm now seeking a replacement valve cover that won't need refinishing like my spare does, unfortunately they are around $400 new if available at all. There's also a lot of blow-by but since this is the first new all forged engine with big ring gaps I've had my hands on (0.018" gaps), I don't know what is normal.

My 3D printed valve spring compressor


Plugs showing evidence of being rich (as expected) and oil burn on 3 & 5...



After datalogging as I progressively turned the boost up to around 12psi I decided the S366 is too big, and that the possibility of 700whp+ was not worth the lag, so I bought an S362SXE on black friday sale to replace my S366. I'm expecting that going from a 66/91.4mm compressor to a 61.4/83.5mm compressor, and from an 80mm turbine to a 76mm turbine, I will gain valuable boost response, and still be able to do 600whp+. Below is a piece of a log from a 3rd gear pull, as you can see my boost is still building at 5,000rpm (the vertical line marker). Of course I didn't know when I ordered the turbo that the valve seals wouldn't stop the oil burn, this car may never even make 600whp with that issue.



The S362 and S366 compared. They are the same size on the outside but different internally.





Condor speed shop fall meet


This has continued to be a frustrating project, it's not at all rewarding having the money to do everything right instead of cobbling together junkyard/used parts, when having more issues than I ever had in my shoestring budget builds like my Volvo and my E30. More on that to come.

[varg]

The timing of the smoke, mostly when I stab the throttle for a quick rev, taking off from a stop, and sometimes on startup, doesn't point to typical turbo smoke.There was also no oil residue in my throttle body. I immediately started checking other things honestly because I've never had any smoke from a turbo on the E30 with the nearly identical 4AN feed and 10AN return to pan, even with Turbonetics turbos, which are arguably lower quality than Borg Warner. I'm planning to have a friend who is also a car enthusiast and a mechanic follow me this weekend and tell me when it smokes, but so far I've had no evidence that it smokes on overrun or at WOT, other than what sounded like the thin dark smoke typical to a turbo car when my wife described it to me while following.

[Dj Buttchug]

Is there any evidence of oil getting out of the turbo housing? Oil restrictor correct in oil line? Maybe you've checked all this already just thinking out loud. I would assume you have proper oil drainage flow from the turbo housing back to the oil pan. I'm wondering if maybe the oil burning is coming from the turbo and in fact is not the stem seals.

*edit*
Re read dripping found in borescope... 650 miles is a pretty good amount. Might not be to terrible to do seals if you can pressurize the combustion chamber to hold the valves up.

[Digitalwave]

Hopefully the smoke is something relatively simple like the valve seals.

[varg]

It's back on the road now and I'm driving at 7psi of boost, tuning as I go. I've put 650mi on the new engine at this point and it runs well, sounds pretty good, and attracts a lot of attention at cars and coffee compared to the E30. It's not all good though. There is a smoking issue I'm trying to diagnose. I borescoped this week after doing a leakdown test (inconclusive because the old HF leakdown tester has an oversized orifice) and found a drip of oil going down the #2 cylinder wall and oily looking CC and valves. I didn't see oil on the intake side with the borescope through the injector ports so it may be exhaust side. This points to a valve seal issue imo, and I'm ordering new seals. Valve seals on a 24V engine in the car will be a pain in the ass, I put new seals in the head before the first build to avoid just this. I either screwed them up (don't see how, I've done it before and it is a simple job) or they were faulty. I'm hoping the seals fix the smoke and consumption so I can work on turning up the boost. The leakdown test showed consistent results across all cylinders though, a fair amount of air came out of the breather hose for all of them, I'm unsure how much is normal for a forged engine with big ring gaps as I've never had anything but frankensteins and old OEM engines. The engine was not cold, but it had cooled for an hour or so before I started the testing. It is a pain to get this car to TDC, it's impossible to see the timing marks from the top, I have to go under the car and stick a mirror up between the radiator fans and crank pulleys then shine a light up to see the marks. I put blue paint pen marks on the trigger wheel that line up with a fin on the oil pan so I can do it from the bottom in the future.

Cars and Coffee 10-15



The ECU box/harness heat shield I added shortly after the turbo heat shield.

Glad to see this back up and going forward. Keep after it! The last we read on this thread made me sad :(

Well done! I have been patiently waiting for an update. Nice to see things are looking up.

Thanks guys, the issues I had took the wind out of my sails on this build, it went from a hobby experience that taught me TIG welding to a chore, and with the E30 needing some repairs pressure was on to have a driveable wagon.

VARG nice wagon! Here’s some food for thought the machine shop I use specialize in big American iron from N/A street cars to NHRA alcohol burners. When I take a block and pistons to them they ask this,

N/A only
N/A with juice ( NOS)
FI only
FI with juice

All versions get a different piston ring end gap stack for the same bore based on piston top / ring temp. I only built N A versions, but he busts me every time I come thru the door.

Thanks. I gapped the rings per the sheet that came with the pistons. They recommend 0.005-0.0055" per inch of bore for the compression ring in for high hp turbo engines, so I gapped to 0.018". Regardless, I don't think that my ring installation caused the scoring because of the lack of scratches when I turned the engine over by hand before installing it, I think debris from the plug wells or intake (which was still pretty crusty in some spots when I cleaned it before the most recent assembly) caused the issue.

[PEZ2]

VARG nice wagon! Here’s some food for thought the machine shop I use specialize in big American iron from N/A street cars to NHRA alcohol burners. When I take a block and pistons to them they ask this,

N/A only
N/A with juice ( NOS)
FI only
FI with juice

All versions get a different piston ring end gap stack for the same bore based on piston top / ring temp. I only built N A versions, but he busts me every time I come thru the door.

[Dj Buttchug]

Well done! I have been patiently waiting for an update. Nice to see things are looking up.

[greyis89]

Glad to see this back up and going forward. Keep after it! The last we read on this thread made me sad :(

[varg]

My wagon is finally back on the road, I've put about 45mi on it now and it seems to be running well. In July, I had the engine re-honed, the rings inspected, and the bottom end assembled while I was on vacation. This saved me some time. Luckily the scores weren't too deep and the rings were ok, my leading theory at this point is that there was some debris in the intake manifold or spark plug wells that caused it, either that or my ring deburring was inadequate but I don't see how. Here are some highlights.

3D printed front main seal driver.


The engine going back in the car


Take 3 of new AC lines. And they're still too close for comfort with the downpipe.


The intermediate line that goes through the firewall, stock vs modified


Freshly surfaced head.


Hoodless for the first break in drive.


Heat shield I made so I don't cook my hood and strut tower paint.


I have some troubleshooting to do. There's a power steering leak and either my new heater valve is already leaking or the firewall partition in front of the blower and/or the ECU box partition is getting hot enough that the HVAC (AC not charged yet) is pulling hot air out of it as if the heat is on low. Fingers crossed that the AC lines are ok with the aluminum heat sleeve and relocation, and that the lines getting too hot and pressures rising past the cutout switch point was actually the problem that was causing the AC to work for a while then kick off and refuse to work again until I unplugged the AC control module to reset it. If not, I have an AC control module to replace or fix, and I hate that stuff. I might try to bypass it and put it on a manual setup like the E30.

[Dj Buttchug]

Damn... :( If it catches your nail the old school rule I learned was its about .002 which is pretty decent unfortunately. I feel this pain. So many setbacks when building something. It can really take the wind out of your sails. On my build I ran into several transmission issues one after the other. Transmission in/ out count on my car is now at 6... Stuff like this sucks but makes the final product when done and working as designed that much sweeter.


Keep on hammering dude!

[varg]

Since last posting I ran it until hot after putting it in the garage for head removal and did a hot compression test, seeing more consistent numbers across the board when hot. I purchased a borescope with side camera and checked the cylinders again, and decided to pull the head based on what I saw, which looked to me to be pretty bad scoring on 1, 4 and 6. I reached out with those images to an old classmate who I trust, older student like myself but a real smart and hard working guy in engineering school who built engines and did machine work for years, mostly on 2JZs IIRC. He said there's definitely skirt scuffing and asked what the cylinder wall clearance is; unfortunately I don't have the answer to that I can only assume machine shop used the specified clearance on the piston sheet when the job was handed off to them, 0.0035". I had no direct communication with the machine shop though, it was outsourced to them.

I've pulled the head now, the news is not great. The piston tops were very oily and covered in carbon grit but there is no damage visible. Bores of 1, 4 and 6 each have a scratch that catches my nail, as I suspected from the higher res borescope images. The scuffing seems cosmetic, I can't feel it, but the pistons rock a lot more than I would expect. This comes with a big caveat that my experience with disassembling and checking such a thing with forged pistons is zero, so I don't know how much is normal. This is after all the first time I've built an engine with forged pistons.

Last time I'll see this for a while:


Hot test results:


Borescope image of the cylinder 4 scratch (the one highlighted by the glare about 1/3rd of the way up)


Borescope image of the cylinder 1 scratch:


Current status:


To be continued.

[econti]

In my uneducated opinion:
I wouldn't worry just yet. Concerns about being too harsh on break-in are unfounded. Boroscopes often make scratches look worse than they are, just the way the light works on them. Could be as simple as a little carbon on the valve on that hole, and it not quite sealing correctly, which if you're running rich is certainly an option.
That hp/L is high but isn't insane.
Drive it a little more.
Can always have the block bored then sleeved and re-use the same pistons.
Also, rings rotate on the piston, staggering the gaps doesn't really matter past first start.

[hasa]

Okay, you've done careful considerations. Time to pull the head and specially the pistons to see if there are problems with ring clearances etc.

But... just to adjust expectations. Running 230hp/litre BMW is dancing on the razor's edge all the time no matter how careful you are. Bad fuel one day. Small mistake with mapping. Slightly over abusing the engine. Many scenarios where evil things can happen. I would not rely my daily driving on that, even it is fun!

[varg]

I appreciate the hopeful input but I'm sorry guys, I just am not comfortable trying to make 230+ hp/L on an engine that is all scuffed and has scoring of unknown depth, and DDing it. I have tuned a couple of cars making these kinds of numbers, and they were not the kinds of builds where you would wonder if stuff looked like this inside. I don't know what's causing it and it isn't supposed to happen regardless of who else it may have happened to. I also found those 4 metal slivers on the magnet which has me worried about a broken ring and noticed a loud tapping in the video of me pulling out of the driveway for the first drive which I could not hear in the car with the exhaust booming in the cabin which may indicate a more serious issue or just a lifter that wasn't pumped up. Can't tell.

Cylinder 4 in particular has me worried with a particularly bad looking mark. I won't have access to the scope for another week or so to take a second look, so I'm planning to pull the head this weekend and inspect the bores, then I will pull the engine if I feel anything in these scuff or score marks. Unfortunately I didn't take the best borescope pics: you can't tell which way the camera is facing and some seem to be inverted but maybe not all. But here they are including the newer ones like # 4. I don't want to continue run with a serious problem it and trash the bores and/or pistons if I can avoid it. These pistons are now $200 more than when I bought this set, and if I have to get another block machined and o-ringed because the bores can't hone out and stay in a reasonable piston clearance range with the ones I have I'm out a significant sum of money. I have built a few but I am not an engine builder, nor do I know any who would look at these pictures and give me an experienced response. I am extremely bummed but I'm unwilling to just wing it and possibly make a $2500 mistake; trashing my pistons and block in addition to what are likely already trashed rings. If I don't feel anything in the scuff or score marks, we'll see how I feel about running it.

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Completely bummed out to see it languishing again, but I also need this car on the road ASAP because my E30's clutch is beginning to fail, the engine has been producing metallic oil for the better part of a few years now, tracked closely by oil analysis, and the rust is accelerating being outside all of the time. I did get a new phone though to replace my iphone 8 with its failed camera, so at least the continuation will be easy to document. I don't like having my DSLR around in the garage.