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MCI 102-C3 coach to RV - Engine Bay

Special delivery from Tom Nelson. Time to knock the Garrett off.

Edit: Had some Polaris 3/8" wheels studs next to my laptop and the turbos beside me. The wheel studs are a perfect fit on a T4 flange.

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A lot going on at once. Kinda the theme of the thread, eh? Picked up a couple 1/4" NPT caps today and a fuel hose adapter with 14mm-1.5 threads is on the way. Modified the caps so that I can solder them to a copper or brass pot. I still want to test these senders to see if either one will work to control the PWM radiator fan controllers. It's a shot in the dark, but a helpful bit of info for anyone looking once I map them.

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Pulled all the up piping, the turbo, manifolds and compressor outlet elbow. She juicy. The need for valve stem seals here and there is evident. The turbo was obviously dumping oil out of the turbine side. I'm making my way to the center of this beast one step at a time.

A few small knicks readily visible on the blower lobes. Nothing detrimental that I can see yet. A little too much backlash in the blower. I've been anticipating maintenance adjustments to every component on this since purchasing it. It's all just a matter of getting to it.

I'm not sure what I'll get around to tomorrow yet. Soon enough, I'll start measuring the exhaust for a flange layout and what pipe assortment to assemble. I kinda want to fire it up without the exhaust on so I can see if it still blows a bunch of burnt oil. I still suspect something is pooling oil in the air box after the engine is shut off. Gotta pull the drain hoses too to see if they're clogged at all.

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[486] said,
JNHEscher said:
Pulled all the up piping, the turbo, manifolds and compressor outlet elbow. She juicy. The need for valve stem seals here and there is evident. The turbo was obviously dumping oil out of the turbine side. I'm making my way to the center of this beast one step at a time.​
any time a detroit is run without enough load you'll get oil in the exhaust, it's just natural
 
[486 said:
;44612396]

any time a detroit is run without enough load you'll get oil in the exhaust, it's just natural​
I know the two-strokes blow oil from every orifice regularly. Ours is currently burning far more than it should. Huge cloud of blue smoke when I fired it up the morning we were leaving the hotel in TX and I smoked out our entire block in Alamosa when I started it up to go get plates.
 
MarkObtinaro said,

The longer and harder you run a 2-cycle DD and as long as you don't overheat it the cleaner the exhaust will get.

I had an MCI with an 8V-71. When I got it the thing smoked blue/black something chronic. After running it for about 2,000 miles it would briefly smoke on start up but once it got going no more smoke.

I will admit that after a day at the ski area and spending several hours on fast idle it smoked pretty bad going down the mountain. Once it finally got fully warmed up again no more smoke.

My bus with a Cat 3208 smoked worse on start up than my 8V-71.
 
MarkObtinaro said:
The longer and harder you run a 2-cycle DD and as long as you don't overheat it the cleaner the exhaust will get.

I had an MCI with an 8V-71. When I got it the thing smoked blue/black something chronic. After running it for about 2,000 miles it would briefly smoke on start up but once it got going no more smoke.

I will admit that after a day at the ski area and spending several hours on fast idle it smoked pretty bad going down the mountain. Once it finally got fully warmed up again no more smoke.

My bus with a Cat 3208 smoked worse on start up than my 8V-71.​
I'm definitely expecting it to smoke from time to time. The amount it expels right now is well beyond excessive. No doubt thought that I can get it to clear up. My curiosity should be satisfied once I get around to pulling the inspection covers and then the blower and aftercooler.

I think I've explained on here what it was doing, but maybe not in great detail. Warm starts were clear, of course. After the engine had sat for several hours (cold start), upon firing it up, it would immediately blow huge puffs of blue smoke on each and every exhaust pulse, so I knew it was coming from all eight cylinders. The amount of smoke would remain equal on each pulse and slowly diminish in a linear fashion over about a 15 minute time span (until warmed up). Once the blue smoke stopped, the exhaust would be completely clear. As clear as the eye can see, anyway. This was all at idle speed. No fast idle or revving. My conclusion was that either the air box is filling with oil draining off the blower or something and each cylinder was sucking in an equal amount, or the previous owners had run multi-grade and the liners were all so worn that the rings weren't seating until the heat had expanded them enough. The air box seemed more likely.

I may find that all is fine and I do need to beat on it like a proper Detroit wants to be beat on. Soon to know. I think it's worth opening it up for inspection either way. A gearhead and his curiosity.
 
NRE T4 d-port divided entry. Didn't find much to match the tapered d-port shape. Started sketching it for a water jet.

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Checked my sketch dimensions on the manifold flange once more with my new caliper. Everything is splendid. Now, the process. Send Cut Send is offering 30% right now. That makes for $95 for two laser-cut flanges in 1/4" 304SS which is their thickest cut they make, $139 at normal pricing. The OE manifolds have flanges that are 1/2" thick and the studs have a 1/2" shoulder length. The only online water jet outfit I found that would take a quick DXF is Big Blue Saw. $153.xx per manifold in 1/2" 304SS or $252.xx each in low-taper cut. I haven't had anything cut in metal as thick as 1/2", so I'm unsure of how much taper to expect. Not that it would make a big difference on an exhaust manifold with such large ports.

1/2" thick is much preferred because of the amount of welding and the spacing between stuff, though there will likely be a bit of warpage from laser-cutting heat anyway. Suppose I could deal with 1/4" because the price is hard to beat. Either way, I'll be bolting the flange to the heads before welding any tubing to them. I found that one of our local steel suppliers (Western Steel) does water jet cutting. Can't get a quote from them until after the Send Cut Send sale ends tomorrow eve. Local would save on shipping, but I'm not sure their machine prices are competitive. Thoughts?

Edit: submitted the file to eMachine Shop for a quote in 1/2". There was no process selection. Hope to see a quote some time tomorrow.


Also found the correct turbo flange. I'm sorely disappointed that it has to come from CX Racing. https://www.cxracing.com/EB-T4-DUAL-CAST-VB_2-2_KIT
Their stuff is junk, but I can easily run either of the three mating surfaces over a stone to flatten them if need be. The NRE turbos are T4 divided entry and the match for the 8V92 exhaust ports is 2.5" pipe. I bought a 12" section of 2.5" schedule 10 304 stainless off McMaster Carr a few weeks ago to make the transitions coming from the manifold flanges. I was looking at going with the T4 collector from Stainless Bros. Kinda costly and splits to 2.25" which I can make work - http://www.stainlessbros.com/225-T4-...ing_p_400.html The CX Racing collectors are about $100 less each and have the plus of being the right size and v-band. I guess most everything is made in Chine these days, so it is what it is. Might shell out the extra $200 for the SB collectors just to avoid the Chinesium.

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Final project for the night was an aluminum anvil for the exhaust manifold project. This will hold one end of the 304 cast schedule 10 round while I press the other end into the exhaust port shape. Went ahead and drilled it for 1/8" NPT so I can double this as a purge plug when I get to weld up the manifolds. I machined the inside portion with a 0.002" clearance fit and put a 2 degree taper on about 80% of it for easy installation and removal.

Good day overall. I'm pretty insistent on shaping one section of the straight stainless manifold tubing to be sure it works as planned before ordering anything from McMaster.

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There's probably some rule of thumb of what length to use here, but I'm thinking I'll just quarter the whole length of the 12.1" tube as equally as I can and give one piece a try in the vise. Gotta go from round to the oblong port shape and a 3" length of tubing looks sufficient enough to make the complete transition.

Wouldn't have thought that the tubing would be from Taiwan, but there it is.

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[486] said,

waitwhat
they already got real nice cast log manifolds
don't make tubular ones, you'll be real disappointed when they warp all over as they heatcycle
 
[486] said:
waitwhat
they already got real nice cast log manifolds
don't make tubular ones, you'll be real disappointed when they warp all over as they heatcycle​
I'm using cast stainless pieces for everything but the head flanges. Kinda had to go this route because the turbos we got are divided entry and Detroit never made a divided entry manifold. Would have gone with thicker wall tubing. Schedule 10 ID happened to have the exact same area as the oblong ports in the heads.

I spent hours and hours looking over every manifold that was ever made to the 4 and 8 cylinders. Anything that came close to what I needed was gonna cost $2k+ per manifold for some old cast iron. Sure would love to be able to cast my own stainless manifolds.
 
02rexwi said,
JNHEscher said:
I'm using cast stainless pieces for everything but the head flanges. Kinda had to go this route because the turbos we got are divided entry and Detroit never made a divided entry manifold. Would have gone with thicker wall tubing. Schedule 10 ID happened to have the exact same area as the oblong ports in the heads.

I spent hours and hours looking over every manifold that was ever made to the 4 and 8 cylinders. Anything that came close to what I needed was gonna cost $2k+ per manifold for some old cast iron. Sure would love to be able to cast my own stainless manifolds.​
I believe the flange size between a single scroll and twin scroll T4 turbo is the same. Why not just use a single scroll manifold with the twin scroll turbo? Are you worried about the performance benefits of using a twin scroll?
 
[486] said,
JNHEscher said:
I'm using cast stainless pieces for everything but the head flanges. Kinda had to go this route because the turbos we got are divided entry and Detroit never made a divided entry manifold. Would have gone with thicker wall tubing. Schedule 10 ID happened to have the exact same area as the oblong ports in the heads.

I spent hours and hours looking over every manifold that was ever made to the 4 and 8 cylinders. Anything that came close to what I needed was gonna cost $2k+ per manifold for some old cast iron. Sure would love to be able to cast my own stainless manifolds.​
I guess, you spent the ridic money for the rev rot turbo, may as well at this point

pulse scavenging isn't really a thing on turbo setups, actually isn't even really a thing on supercharged setups either, thus the little zoomies on piston aircraft engines rather than a proper collector

then the twin scroll thing is about hot side internal volume, with it you can cut it in half relative to single volute, so the pressure pulses stay at a higher pressure/temperature and therefore energy before the turbine
meaning, since you're going to the effort, you'll want to keep the internal volume of your manifolds to a minimum, even though it means using a smaller diameter tube.
 
02rexwi said:
I believe the flange size between a single scroll and twin scroll T4 turbo is the same. Why not just use a single scroll manifold with the twin scroll turbo? Are you worried about the performance benefits of using a twin scroll?​
Not a huge concern. The flange patterns are the same so it would bolt right on. Pretty curious what these will do on a 736 cubic inch two-stroke.
[486] said:
I guess, you spent the ridic money for the rev rot turbo, may as well at this point

pulse scavenging isn't really a thing on turbo setups, actually isn't even really a thing on supercharged setups either, thus the little zoomies on piston aircraft engines rather than a proper collector

then the twin scroll thing is about hot side internal volume, with it you can cut it in half relative to single volute, so the pressure pulses stay at a higher pressure/temperature and therefore energy before the turbine
meaning, since you're going to the effort, you'll want to keep the internal volume of your manifolds to a minimum, even though it means using a smaller diameter tube.​
You sayin' I should just put zoomies on this beast?
 
[486] said,
JNHEscher said:
You sayin' I should just put zoomies on this beast?​
I'm sayin that whatever shit cast dog logs they came with will perform 99% as well as perfectly tuned blah blah blah that'll probably push gaskets out because the tube heats up way faster than the flange so the differential expansion makes the flange pull up on the center cylinders or crack the welds. Best case you can get some MLS gaskets that at least won't push out, or just run the manifold flanges on the bare heads and deal with soot everywhere.

I've been forced into making maybe 5-7 turbo manifolds and used maybe the same amount of cast iron manifolds when they're available and fit. Every time without fail I hate the tubular manifold for the above mentioned reasons.
 
[486 said:
;44767578]

I'm sayin that whatever shit cast dog logs they came with will perform 99% as well as perfectly tuned blah blah blah that'll probably push gaskets out because the tube heats up way faster than the flange so the differential expansion makes the flange pull up on the center cylinders or crack the welds. Best case you can get some MLS gaskets that at least won't push out, or just run the manifold flanges on the bare heads and deal with soot everywhere.

I've been forced into making maybe 5-7 turbo manifolds and used maybe the same amount of cast iron manifolds when they're available and fit. Every time without fail I hate the tubular manifold for the above mentioned reasons.​
I gotcha. Just messing with ya. The OE manifold gaskets are MLS and the turbos came with steel gaskets. Kinda doubt anything I chose to use for this is going to hold back any exhaust leaks for extended periods. The stock manifolds and pipes tend to leak. Particularly oil as they wet stack.

I gave up on stock manifolds because the one or two styles I found that I could work with by using an adapter were either way too expensive or I could only come up with one side. I really did try, though. The twin scroll feature was not something I opted for. That was a last-minute discovery before we ordered them.
 
The mailbox gave me some more bus goodies today. Six more stainless washers to machine for the 1" electrical conduits to pass through and a pair of Torque Solution offset drain flanges for the snails.

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I think I'll have one exhaust oblong to round transition made and sixth floor sheet tacked tomorrow.

Can't believe I didn't snap a carbide insert. Took forever plunging it into the stainless tubing a very low RPM. Almost got through the tube wall. Cut the rest with the cutoff wheel and faced the ends flat on the lathe. Stamped the aluminum anvil into the tube with a dead blow hammer and started clamping the other end down in my 5" vice. It's working. I'll use this first piece to set the stop distance between the vice jaws so the rest of the transitions are made quicker.
 
I guess I have a lesson in geometry that I have not yet encountered. I used 2.5" tubing to match up the oblong port area. The calculated area of each are nearly identical. Same circumference, too. However, squishing said tubing into the oblong shape does not end up at the same width when the vice jaws bring it to the same height. It's been a while, but I think I vaguely remember there being a function to use when working with ellipses that would give me the correct size tubing to use.
 
[486] said,

on the turbo manifolds I had a thought last night, all my fabricated manifolds have been log style without very long runners, so the thermal expansion of that log puts a lot of force on the flange, where if you made it like a normal header with long runners they'd probably flex around just fine.
 
I'm thinkin' there's some slight confusion about the manifolds. I wasn't planning to go with a log style. Probably more of a long-tube type. I'll play around with McMaster parts assemblies after I get a port transition made.

The quickest and cheapest way to find the right tube diameter that I can think of is to grab some o-rings that match tube specs and see which size wraps the port circumference. The 2.5" tube not forming to match the port kinda threw me off. Once (and if) I get the tube size correct, I'll throw together a CAD view of the manifolds. 3" tube is next size up. Drawing the ID of 3.26" over the port sketch looks much better. If I had drawn the 2.5" ID over the sketch, I might have caught the discrepancy beforehand.

Edit: Added the sketch view. Blue has the 3" tube ID drawn over the port sketch, white has the 2.5" tube ID. Safe to say that I could just order the 3" stainless and try it out since the next size up is 4". Schedule 40 iron 3" has an ID of 3.068".

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CarterKaft said,

Building exhaust manifolds for a 100% duty cycle industrial engine is not trivial and even OEMs don't have the best luck.

What was the reason for this anyway?
 
CarterKaft said:
Building exhaust manifolds for a 100% duty cycle industrial engine is not trivial and even OEMs don't have the best luck.

What was the reason for this anyway?​
The backstory to the turbo swap is that the OE turbo on these engines sits on top of the blower and the cast aluminum compressor wheel eventually starts to break apart and blow its pieces directly into the blower. Despite the suggestions I received about how much cheaper I could get a remanufactured turbo, the quotes I got ranged between $2700 and $3400. I saw Tom Nelson's mirror twins on sale again and started asking him about sizing. For $2830 shipped, I said screw it, let's do it.

Removing the big single opened up 11+" of room atop the engine where there used to be close to none between the turbo and miter box tray. Setting up a turbo at either side of the engine with the manifold piping staying downward will stop oil from pooling in the exhaust. I found out a few weeks ago from another Detroit owner that drowning your two-stroke in its own lube is a killer.

Finding out that the Nelson turbos are twin-scroll at the last minute prior to ordering them in time to meeting the sale deadline was kind of a bummer, but cool at the same time. Because there aren't any divided entry manifolds for the two-stroke, I got the itch to play around a bit and make my own like others have. I'll agree that it is overkill. Most of what I fart around with tends to be, and I kinda like it that way. What I originally had in mind with the twin swap was to use a marine two-stroke manifold so that I could find or make a bolt-on adapter if needed. The prices were sky high at the time that I was browsing. Could still happen. At the moment, I continue with the urge to build some.
 
Took a pic of the v-band found on OE manifolds. There's one or two OTR manifolds for the 8v92 that have a four-bolt flange. Don't know their pattern. The v-band flanges only hold thin wall tubing to the manifold, therefore aren't capable of supporting a turbo for long.

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CarterKaft said,

Building stands for the turbos and reusing the OEM manifolds seems like the super easy method, much like a 7.3 PSD CAT 3208 etc. but with two pedestals instead of one.

A man with your CAD skills could make quick work of that.
Use stainless bellows in your new up pipes and just mild steel for the pedestals.

Maybe like this?https://images.app.goo.gl/y7UQErjj8nY2rdwHA
 
CarterKaft said:
Building stands for the turbos and reusing the OEM manifolds seems like the super easy method, much like a 7.3 PSD CAT 3208 etc. but with two pedestals instead of one.

A man with your CAD skills could make quick work of that.
Use stainless bellows in your new up pipes and just mild steel for the pedestals.

Maybe like this?https://images.app.goo.gl/y7UQErjj8nY2rdwHA​
Had a lot more to add to my last post. Got cut short with a disc about to go south again.

I'll have to watch some Fusion 360 lofting tutorials tomorrow to figure out what it takes to make a loft to include a wall thickness spec. Using 3" stainless schedule 10 sizing. Drawing the transitions isn't necessary to assemble the McMaster Carr parts, but it's a super simple process to add to the visual. Fusion is such a badass program. I have a plane offset at 3" for lofting the oblong to round transition length and can change the offset with a couple clicks if I need to extend the transition length.

With the transition centers placed on the offset plane, I can directly insert any one of the parts in the McMaster catalog and assemble them in any arrangement to play with pipe elbows until they meet up how I want. A complete header mock-up kit at no expense with the bonus of identifying any degree of tube rotation. 5VZ-FE turbo manifold I created in blue glass a couple years ago.

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