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Tier 4 VS Tier 3 Fuel Efficiency

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Posted by bogie_engineer on Sunday, October 25, 2020 2:43 PM

Leo_Ames

Any thoughts on Norfolk Southern's GP34ECO that's now being tested, Bogie Engineer? Looks like a much more compact installation this time around (albeit with a smaller 12-710) than a tier 4 710-powered SD70ACe would've required back in the early 2010's.

I'm curious with projects like this, if they've improved the fuel burn rate compared to your stillborn project? Interlake Steamship for instance is building America's first Great Lakes freighter in over 35 years using a pair of Tier 4 certified 16-710's for her engine installation.

Has EMD/Progress perhaps been able to tone down how much EGR would be needed today compared to a decade ago, enabling competitive fuel consumption? Or was that only a problem had EMD pursued a 710 powered tier 4 SD70ACe without DEF?

 

 
It's been 5 years since I worked at EMD and I'm not connected to anyone on the engine side of engineering so don't know any specifics of this installation. The only thing I've seen online is that it uses DEF but see no mention of oxidation catalyst or particulate filter that was part of the system I was designing the loco around in 2011. With age, the equipment should get smaller and appears to have based on the loco pictures. I'm guessing it has no or minimal EGR since there doesn't seem to be a spot for the big roots blower and cooler of the previous 12-710 arrangement done for UP about 10 years ago. A big question to me is what injection system it has; if it has the common rail system as on the Tier 4 1010J, the hit on fuel economy compared to a Tier 3 710 may not be great. The extra back pressure of the SCR would hurt economy but the improvement of common rail and whatever they've done to the turbo may largely offset it. But it's all a guess for me as I really don't know.
 
Perhaps if this is a success, they may work on a 16 cyl version if the aversion to DEF on the freight railroads can be overcome. 
 
Dave
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Posted by Leo_Ames on Sunday, October 25, 2020 10:34 AM

Any thoughts on Norfolk Southern's GP34ECO that's now being tested, Bogie Engineer? Looks like a much more compact installation this time around (albeit with a smaller 12-710) than a tier 4 710-powered SD70ACe would've required back in the early 2010's.

I'm curious with projects like this, if they've improved the fuel burn rate compared to your stillborn project? Interlake Steamship for instance is building America's first Great Lakes freighter in over 35 years using a pair of Tier 4 certified 16-710's for her engine installation.

Has EMD/Progress perhaps been able to tone down how much EGR would be needed today compared to a decade ago, enabling competitive fuel consumption? Or was that only a problem had EMD pursued a 710 powered tier 4 SD70ACe without DEF?

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Posted by daveklepper on Sunday, October 25, 2020 5:49 AM

I'm booting up this old thread, istead of starting a new one, because allthe "Tiers" relate to air-polution.  Locomotives got regulazted only after Auto Regulation had some success.  The following URL leads to atory about an important component in that success, which will interest most readers:

https://alum.mit.edu/slice/lessons-clean-air-car-race-50-years-later

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Posted by Overmod on Saturday, June 20, 2020 5:51 PM

Erik_Mag
From my understanding, GDI engines often produce an even higher amount of nanoparticles per horsepower hour than diesel engines.

The principal issue, I think, is quench at very high rotational speed when very small injected charge (VW claimed to get this reliably down to the 35,000 fuel molecule per injection range, the only specific number I've seen) with air metering near theoretical stoich and wall quench.  The fuel droplets burn off hydrogen selectively but complete carbon oxidation does not complete in the short combustion interval.  This is different from sooting where there is either overfueling for the available oxygen (as seen elsewhere in Alcos and in 'rolling coal') or improper injection conditions that leave fuel only partly burned (most of the hydrogen comes off, but some remains or recombines in new combinations in what are usually coarser droplets.

In my opinion the only real solution to nanoparticulate soot is to expose it to adequate oxygen and promotion while it is still hot enough to react fully.  

At Princeton there was a group, back in the 'obligate carburetor days' before cheap ubiquitous microelectronics and piezos made individual GDI or even port injection cost-effective, that experimented with extreme lean-burn by charging the fuel and the jets up to over 35kV (so the fuel spray particles would self-repel).  This was the first place I saw insulative ceramic coatings used inside IC engines, before Ford experimented with them as thermal-barrier coatings in a different context, and some of the Polimotor research (if I remember correctly) provided similar self-charging repulsion in cylinder walls and chambers.  You could perhaps accomplish better assured atomization this way ... although I thought it was mad science coupled with a little lack of common sense to use high voltage around gasoline in a vehicle slated for typical American maintenance practices...

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Posted by Erik_Mag on Saturday, June 20, 2020 4:57 PM

Overmod

Interestingly enough as it develops at least some types of GDI engine also produce nanoparticulates in the critical size range, something I think will be trotted out with appropriate miming of horror in the future when agendas are formed and have to be met.

From my understanding, GDI engines often produce an even higher amount of nanoparticles per horsepower hour than diesel engines. OTOH, there has been some interesting work at Sandia about "Bunsen Burner" inspired diesel injectors, i.e. using a tube to make sure the air and fuel were better mixed before ignition started. They're claiming reduction in both PM and NOx from better combustion control. What remains to be seen is how well this idea works in a real world engine.

A similar issue is pm from old jet engines, the J79's were imfamous for producing a lot of black smoke.

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Posted by Shadow the Cats owner on Saturday, June 20, 2020 4:02 PM

The DPF is based on the size of the engine and you can not have a modular one as if you do it requires seperate fuel lines to it for the regens seperate power supplies for the heater for the regens and seperate heat sheilds for each one as you do not want a dozen 1500 degree boxed spread out all over the engine.  Your best bet is one spot for everything.  

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Posted by Overmod on Saturday, June 20, 2020 3:12 PM

Shadow the Cats owner
So most locomotives the Diesel Filter would be about 108 Grand to replace when required. 

I believe (and David Goding can comment with more specific knowledge) that locomotive DPFs are modular, probably sourced around units common to large Class 8 truck size.  That might make the aggregate cost go up, compared to the equivalent in a single can, but might also make it go down as economies of scale would make single large filters for a restricted number of locomotive applications more expensive than units built for a shared mandatory market.

Of course the DPF is largely a feel-good solution based on obsolete consderations of the 'social problem' with PM.  Essentially all the nanoparticulates that pose the actual danger sweep through a DPF as if it weren't there, even after the filter matrix has become substantially plugged with what is chemically similar to activated carbon.  Interestingly enough as it develops at least some types of GDI engine also produce nanoparticulates in the critical size range, something I think will be trotted out with appropriate miming of horror in the future when agendas are formed and have to be met.

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Posted by Shadow the Cats owner on Saturday, June 20, 2020 11:47 AM

This should give you an idea of the costs of Diesel Particulate Filters as yesterday we had to replace 2 for trucks out of warrenty.  The filter alone for one of our trucks is 9 grand for a 500 HP engine.  The average repair cost for a diesel emissions control engine on a OTR truck is 25 grand when they fail with 20 grand of that being parts alone.  So based on that your looking at about figuring on displacement as each filter can only service a certain size of engine so with our engines being 15 liters.  So most locomotives the Diesel Filter would be about 108 Grand to replace when required.  The way it looks like is about a 10X increase in what it costs to repair an OTR truck compared to a Locomotive.

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Posted by Overmod on Friday, June 19, 2020 9:21 AM

Psychot
Was the railroads' resistance to DEF driven entirely by the cost of infrastructure to handle it, or were there other concerns?

At least some of it is in the straight cost; it is seen as essentially an unfunded mandate, and with some justification it puts an outsize welfare-economic penalty in railroads for the relatively small absolute NO/NOx reduction (leveraged as it is by other pollution reductions) it actually produces in current practice.  The argument that it increases effective fuel cost is a bit specious in that most of the direct cost can be surcharged to customers just as fuel-price spikes have been.

It's also a technology with some dramatic bad press, in part due to the Government shooting itself in the foot by mandating the same sort of 'forced derating' if the DEF system fails or runs short that it imposed on motor-vehicle owners.  Railroad owners are not such fools as to accept this in freight service where even relatively small failures of locomotives can have critical results.

I do not know whether unions have weighed in on safety or other 'employee' issues, and would appreciate hearing about any opinions or actions.

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Posted by Psychot on Friday, June 19, 2020 8:04 AM

Was the railroads' resistance to DEF driven entirely by the cost of infrastructure to handle it, or were there other concerns?

BDA
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Posted by BDA on Tuesday, June 16, 2020 6:23 AM

I agree , the "cab" rides better in a 70ACe than a 90MAC .

When the 90s go into earthquake mode at lowish speeds things can get a bit violent in the cab .

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Posted by NorthWest on Tuesday, June 16, 2020 12:34 AM

My understanding is that sourcing the rubber bushings has become an increasingly expensive problem as the units with first generation isolated cabs have aged, and that this is part of the reason that SD70ACU rebuilds have had their cabs replaced.

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Posted by bogie_engineer on Monday, June 15, 2020 8:02 PM

The NA isolated cabs starting with the SD60I were mounted on four bushing-type isolators acting with rubber in shear to get greater deflection and lower natural bounce frequency. Eventually the isolators settled and grounded out the isolation. They also had some bad modes of vibration; if the trucks hunted, the cab would diagonally pitch and it was hard to stay in the seats, that was a particular problem on the SD90MAC/43's on a specific stretch of UP track where they set the gauge intentionally tight causing the trucks to hunt at around 65 mph. The isolated cab for the SD70ACe had redesigned isolator mounting and orientation raising the isolation frequency but still low enough to be effective.

Dave

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Posted by M636C on Sunday, June 14, 2020 10:17 PM

bogie_engineer

 Getting to an isolated cab was talked about for the -2's as we knew that isolation of the engine or cab was the only way we would do any better than the slight improvements on the -2's compared to their predessors. It was only with Conrail insisting on a quieter cab that the first isolated cabs for NA got built - there was no way the organization was ready to isolate the engine due to the alignment of the engine to generator using the rigid mounting to the underframe. I actually proposed an isolated powertrain for the SD80MAC when I started that project but management quickly shot that down in favor of the isolated cab. But as the experience with isolated cabs long term reliability issues surfaced, the management was finally ready to accept the isolated powertrain. 

Dave 

What were the reliabilty problems with isolated cabs?

I haven't heard of problems with Australian isolated cabs. These are an interesting design and are supported at waist level, just below the cab windows. This reduces the interior cab dimensions and makes it harder to lean out the windows but reduces the forces on the flexible supports. It also allows a fixed shock absorbing area in front of the cab.

One type, the JT42C, had isolated cabs at each end. These had the original 12-710 which suffered from greater vibration than the later engines with the revised firing order. One group of units, the AT42C with rigid cabs and the original 12-710, is rarely used except as trailing units now.

Could supporting the cabs at waist level reduce the problems seen in the USA?

Peter

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Posted by Shadow the Cats owner on Sunday, June 14, 2020 6:26 PM

Part of the problem with any 2 stroke design is the simple fact you need some sort of positve air pressure to force the next charge into the cylinders while the current one is still in them and push all the air out.  On a 2 stroke gas engine they use the piston itself to create that pressure and a set of reed valves on most small engine equipment.  On larger diesel engines they use a blower driven off the crankshaft to create that pressure.  That's why most 2 stroke engines will load faster than any 4 stroke is they are producing more power per RPM as they are always on the power stroke on the downward strokes.  On the four stroke engine you have a seperate stoke to both get the fresh air into the cylinders and get rid of the exhaust so they also tend to burn cleaner Alco's not withstanding and their turbo lag problems from governors that were not set right.  We have a farmer around here that has a older IH that was rebuilt into a monster engine in HP.  The engine is rated at over 900 HP after its latest overhaul and even when the driver stands on it no smoke from the stacks but the freaking thing screams about as loud to me as some of the videos I have seen of the old Turbine locomotives the UP had in the 60's.  

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Posted by Overmod on Sunday, June 14, 2020 2:18 PM

rvos1979
Getting back to trains, I wonder if the backpressure could be reduced by using turbochargers feeding a Roots blown style 710, like the old Detroit two stroke engines, but I suspect that packaging the whole works would be an issue..........

That wouldn't get you anywhere.  The Roots is a positive-displacement blower and its load (assuming it is driven the usual EMD way via gearing from a camshaft) would be correspondingly increased by any turbocharging, whether or not the charge air delivered to it were intercooled or not.  Meanwhile of course the turbochargers when producing meaningful charge-air compression at appropriate mass flow are themselves sources of considerable exhaust backpressure (and correspondingly higher EGT and two-stroke scavenge-flow restriction)

What Mr. Goding is describing is the back pressure imposed by all the flow restrictions in the aftertreatment equipment, downstream of the turbochargers.  This could only be 'reduced' with additional driven pumping (probably not positive displacement) which could theoretically, but not particularly economically, be derived from heat extracted from the exhaust.

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Posted by bogie_engineer on Sunday, June 14, 2020 11:47 AM

Thanks for your kind words Allan. Like I said, I laid the groundwork but others did the detail design of the final product. I was a longtime member at trainorders.com (no longer) and the comments there about the reflections in the windows on the SD70ACe's stuck with me so I did champion that for the T4 as well as the engine isolation. The first 9 years of my career there were spent as the noise engineer doing cab, wayside, and industrial applications. Getting to an isolated cab was talked about for the -2's as we knew that isolation of the engine or cab was the only way we would do any better than the slight improvements on the -2's compared to their predessors. It was only with Conrail insisting on a quieter cab that the first isolated cabs for NA got built - there was no way the organization was ready to isolate the engine due to the alignment of the engine to generator using the rigid mounting to the underframe. I actually proposed an isolated powertrain for the SD80MAC when I started that project but management quickly shot that down in favor of the isolated cab. But as the experience with isolated cabs long term reliability issues surfaced, the management was finally ready to accept the isolated powertrain. Working as the lead mechanical engineer on the LIRR DE/DM30AC's with a small dedicated team we were able to incorporate an isolated powertrain using a skid to maintain alignment, including the equipment rack. That had it's own set of problems but did result in very quiet cabs. But when it was time to do the 1010J for Tier 4, the engine designers finally accepted mounting the alternator off the end of the engine which was always the best solution.

Dave

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Posted by Notch 8 on Sunday, June 14, 2020 12:21 AM

bogie_engineer

 ...we designed the cab to slope the windows and improve the visibility while rigidly mounting it again since we had engine isolation. The cab made it to the final T4, not much else did.  

 

Dave,
I would like to thank you and your fellow engineers for your design work on the SD70ACe-T4.  The sloped windows and very quiet cab are huge improvements over the SD70ACe. 

The vertically mounted windows on the SD70ACe (just like the SD60M triclops) force you to look through the reflection of the rear window on the other side of the cab.  This can be very distracting, especially at night, when you see lights streaking across your field of vision.  Many times over the years I momentarily thought someone was racing across the tracks just ahead of me.

The original, non-isolated cab SD70ACe design is horribly loud in high throttle settings – perhaps even worse than many of its predecessors.  The engine isolation on the SD70ACe-T4 has made for a wonderfully quiet cab.  Now you can actually have a cross cab conversation, while in Notch 8, without yelling at each other. 

When I started railroading in '94, I was a dyed-in-the-wool EMD fan, especially of the SD40-2s, even though they were getting long in the tooth.  Eventually though, I came to prefer GEs, any GE, from the Dash 8s on.  The SD70ACe-T4 has changed my opinion about EMD for the better.  Thank you!

Allan
Locomotive Engineer
UP Seattle Sub
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Posted by rvos1979 on Friday, June 12, 2020 2:33 PM

One would only hope that Cat learned from their mistakes with the 2007 emissions fiasco........

Lots of drivers still remember that, and the International MaxxForce boat anchor that followed a few years after.........

Getting back to trains, I wonder if the backpressure could be reduced by using turbochargers feeding a Roots blown style 710, like the old Detroit two stroke engines, but I suspect that packaging the whole works would be an issue..........

Randy Vos

"Ever have one of those days where you couldn't hit the ground with your hat??" - Waylon Jennings

"May the Lord take a liking to you and blow you up, real good" - SCTV

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Posted by Shadow the Cats owner on Friday, June 12, 2020 8:11 AM

Bogie that mirrors what we have found in the 4 stroke side in the OTR industry.  Heck at the start of the EGR without SCR and DPF era at one point these engines were using 30% Exhaust gas in the next charge at times to make the emisson standards.  Then we added DPF and needed to add regenerations to the mix which took on average 6 gallons of fuel to complete.  We had EGR coolers that would make engines into boat anchors when they failed mixing oil into the coolant and hydrolocking the block normally doing about 1500 RPM tends to make a heck of a mess of the rotating assembly.  Then throw in the Sulphric acid that is created from the buring of diesel and the ablation of the valves from the carbon leftover.

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Posted by bogie_engineer on Thursday, June 11, 2020 8:50 PM

I wasn't close enough to the engine guys to know for sure, but EMD 2-strokes are always negatively impacted by exhaust backpressure and surely the extra piping would add significant backpressure. Prior to Tier 4, the limit on backpressure for turbo engines was 5 inches of water for industrial/marine applications, the straight thru silencer on locomotives added very little. IIRC, at 5" H20, there was a couple of percent increase in fuel consumption. 

For the Tier 4 710, they were looking at two smaller turbos or at turbo compounding, which they are doing on the 1010J.

Dave

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Posted by SD70Dude on Thursday, June 11, 2020 8:24 PM

How well did the 710 run with a SCR/DEF setup added on?  Was there any increase in fuel consumption?

Greetings from Alberta

-an Articulate Malcontent

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Posted by bogie_engineer on Thursday, June 11, 2020 8:08 PM

Amtrak and their state partners are going to SCR/DEF on the Charger locos with Cummins engines and Progress Rail did the F125's for Metrolink with CAT engines with SCR. GO Transit in Toronto has the MP54's with dual Cummins QSK60's with SCR so there will be plenty of experience gained on RR's in North America, just not on Class I's. Before I went back to EMD in 2010 I was working as a consultant for MPI and did the first layouts of the MP54AC retrofit to the MP40 and was able to make it all fit as the Cummins SCR package was much smaller than what EMD was proposing. My guess is that the Class 1's will eventually accept SCR for fuel savings and reliability but it won't be soon.

Dave

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Posted by SD70Dude on Thursday, June 11, 2020 4:08 PM

It seems to be well established that EGR was, and is a failure in the on-highway and smaller diesel engine markets. 

GE seems to have gotten reasonable reliability out of the Tier-IV GEVO engine, but it does use more fuel than its Tier-III counterpart.  It remains to be seen how well they will do in the long term. 

The Class I's still want nothing to do with SCR and DEF.

Greetings from Alberta

-an Articulate Malcontent

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Posted by Shadow the Cats owner on Thursday, June 11, 2020 3:40 PM

It's because of DEF and SCR in the OTR side of Diesel engines my boss has seen our fleet average go from just over 5 MPG just 5 years ago to this year we are slamming over 8 MPG with bigger engines and running a faster truck speed also.  Why the 2020 engines basically only have EGR on them when they are idling.  When going down the road the computers let more DEF be used to convert the NOX into CO2 and Nitrogen.

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Posted by bogie_engineer on Tuesday, June 9, 2020 10:34 AM

SCR is selective catalytic reduction, this website describes it much better than I can:

https://www.dieselforum.org/about-clean-diesel/what-is-scr

DEF is Diesel Exhaust Fluid, the blue liquid most diesel trucks require now that is injected ahead of the SCR to reduce the NOx in the exhaust. It is basicly urea.

Dave

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Posted by freightcarguy on Tuesday, June 9, 2020 10:08 AM
For those of us who aren't "insiders", what is SCR and DEF?
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Posted by bogie_engineer on Thursday, June 4, 2020 9:26 PM

EMD reluctantly accepted that engine isolation was needed for the next generation of locos. The isolated cab caused many troubles although they were quiet. There is actually an SD60 running around Pueblo that has a 12-710 with an elongated oil pan supporting and maintaining alignment with the alternator that is sitting on isolation mounts. That was to be the arrangement with the 710 going forward. Actually, our first application of engine isolation was the DE/DM30AC that I led the mechanical design on. The first iteration of a skid there had fatigue problems brought on by the new firing order 12 but a skid redesign fixed it. 

For the 1010J, the design requirement was to mount the alternator to the cast block like GE has done since day one and put isolation mounts under both the alternator feet and engine feet and this is what was done to make them so quiet. I firmly believe getting the engine vibration off the loco frame will improve the reliability of the electronics and most other systems as a side benefit. 

I can't really speak to the specific troubles on the H engine but they are working on 300 locos in China since about 2007.

So the 1010J really is a new engine with the basic cylinder geometry carried over but completely new turbos (3 of them) and extensive intercooling, aftercooling and EGR cooling plus common rail injection. When I left in 2015 engines were running in test cells but hadn't made it into a locomotive yet. CAT engine experts did look over the EMD engineer's shoulders and were part of all major milestone reviews but the design was done at EMD.

Dave

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Posted by SD70Dude on Thursday, June 4, 2020 4:03 PM

Overmod
bogie_engineer
While we were at it, we designed the cab to slope the windows and improve the visibility while rigidly mounting it again since we had engine isolation. The cab made it to the final T4, not much else did.

The immediate question is whether the prime-mover isolation was kept in the 1010-engined version, or what other measures were incorporated to keep out of a "Thundercab" situation.  What was actually done?  Is there lower inherent NVH with the four-stroke engine?

Progress lists the isolated powertrain as one of the improvements in the SD70ACe-T4 promotional material.  At any rate, whatever they did it sure seems to have worked.  While I have not yet gotten to operate any of the demonstrators CN has tested, everyone who has raves about how quiet they are. 

Here is the SD70ACe-T4 brochure:

http://s7d2.scene7.com/is/content/Caterpillar/CM20170915-63120-29009

 

Overmod
While the new engine arrangement was being designed (the only part used from the H engine was the cylinder head)...

Here is the promise of a definitive answer: My understanding of the 'problem' with the 265H engine was that it largely involved ultrasonic-vibration 'cavitation' (likely sonobubble collapse effect) issues in parts of the relatively thin-wall block.  Was that a factor in redesign, and what were the actual design changes made to produce a workable J-block?

So it IS based on the H-engine, just like how the GEVO rose from the HDL's ashes.

What "design expertise" did CAT contribute to the J-engine's design?  Their EGR systems seem to have been nothing but trouble in both on and off-road engines. 

Greetings from Alberta

-an Articulate Malcontent

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