Let's Clear The Air ...

[DriVer]

Workhorse / MaxxForce 7 "Let's Clear The Air"

Why Workhorse, with MaxxForce® Advanced EGR, can be your best solution for 2010... and beyond.

Please open the attachment and let's discuss ....
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[RustyJC]

In order to have both sides of the issue available for discussion - HERE is the SCR side from Cummins' perspective.

Rusty

[EngineerMike]

TALK ABOUT FASCINATING READING!!!!

the MaxxForce solution lists the following (with my editorialization added):
Advanced fuel injection technology amounting to injection shaping. This is not new technology, Cummins does the same, ditto Cat, and they have all done this for some time.
The proprietary combustion bowl design or cylinder/cylinder head reshaping. Again, this has been going on for decades at least.
Advanced air management featuring dual turbochargers isn't new, but it is different than Cummins.
Improved electronic calibration i.e. updated fuel-air tables to adapt to the other tweaks herein.
MF presents a cost comparison I'll discuss more later.
So in the end, MaxxForce meets 2010 air regs by manipulating existing fuel handling parameters, cylinder geometry, and dual stage intake air pressurizing, but without a urea after-treatment. The document then goes on to make a cost comparison using a urea aftertreatment cost per gallon "which has been seen as high as $12 per gallon" (an asinine and patently false & misleading comparison method), and to make other assumptions unreasonably favorable to the comparison or that have zero verifiable basis (stable resale value? how is that measured for a vehicle that hasn't been made yet?). So discounting the obvious sales puffery, you get engineering tweaks plus a second turbo mechanism offsetting urea aftertreatment.

Now Cummins list (and my editorial):
Selective Catalytic Reduction (SCR) or an aftertreatment process that injects urea fluid into the exhaust stream (can't tell if it is before or after the Diesel Particulate Filter) from a new tank (12-15 gallons on large heavy duty trucks w/12-15 liter engines, probably 8-10 gal on ISB, ISC & ISL motorhomes- my guess).
New Cylinder Head w/Single Camshaft in ISX (15 liter) which is basically a tweak like MF's cylinder shape changes above.
XPI common rail fuel system which is what the Cummins straight 6 engines have had for years, possibly including some unspecified tweaks.
Significant advantages over previous products in terms of fuel economy and further over in-cylinder solutions (MF's methods); Cummins estimates 5-9%, then goes on to offer cost comparisons using 5 and 6% levels, and a baseline of per-1%-improvement.
Cummins goes on with some sales talk, the level of puffery of which is not easy to discern. However they use terms like "Our experience" and "Our testing indicates" which lead me to believe they actually have some data to back up the claims of 5-9% improved fuel mileage over "in-cylinder solutions" (the wording used by MF to indicate their not-by-aftertreatment emissions compliance. Interestingly, MF accepts Cummins' superior fuel mileage claim, tho they allow for only a 2% mileage increase in their cost comparison (the one where they use the highest-ever-on-record cost of urea aftertreatment fluid), while.
Cummins also claims a higher h.p./displacement capability with SCR vs "in-cylinder" though it is impossible from their document to discern if that is effectively the same claim as the fuel mileage advantage, just said another way.
Cummins claims in-cylinder (MF) solutions will require more frequent engine rebuilds, again difficult to quantify, tho the second turbo is likely to engender additional maintenance (turbo's are the highest temperature mechanical device after exhaust valves but spin at stupid high RPMs, and are notorious for issues w/every mfgr I've ever known unless Exhaust Gas Temps are strictly controlled; MF states they will have lower EGTs due to twin-turbo config, but no rationale as to why that would be true or description of over what design).

So where does that take us? I'd take the following away:
1) Both companies issue info that is insufficiently detailed to verify all of what they present.
2) Urea aftertreatment will yield better diesel fuel mileage by probably 4+%, YMMV.
3) MF impeaches its own cost comparison to the point it can be discarded entirely (footnote says "SCR solution maintenance cost increase of $500 per day" which is either a typo or an outrageous and stupid fib; even at their fraudulent figure of $12/gal of urea, that's 41 gallons per day or 3-4 urea fill-ups, DUH!!).
4) Cummins' cost comparison passes the sniff test, but should be taken w/a grain of salt. After all, they are trying to sell engines.
5) Hauling around a urea aftertreatment plant isn't my first choice of things to order on a new chassis. Would rather be without it. But I'm very concerned about operating cost. These silly toys cost enough to operate anyway. So I'd be looking at fuel mileage really close before allowing urea handling problems to make my decision for me.

I was worried about the DPF when it came out. Caterpillar sold their wares claiming they could make it w/out a cataclysmic converter, which sounded good. However, the proof is in the real world experience. I researched a DPF issue I was concerned with fully 3 levels into Cummins' tech support staff, and was met w/welcoming attitude and straight forward answers (eventually getting: "we are pretty certain of what we are telling you, but that's not a guarantee"; happy sales schmooze it wasn't, so I was convinced I got real feedback). After running on a DPF engine, and watching Cat throw in the towel on keeping up in the over-the-road engine overhaul race (they were the previous we-don't-need-no-stinkin-aftertreatment world champs), I'm very happy with my engine choice and the interface w/Cummins. When they tell me they know they have the technology down, I'm comfortable with that. When they push out cost comparison data, they have been doing that long enough to know fleet managers will hold them accountable. An outfit that will lie in a cost comparison to try and look good- well, not so comfortable w/that. Why did MF cheat in their cost comparison? Can't say, especially with such obviously dim witted ways that even this boob can spot. But it casts a pall on their other claims.

[RustyJC]

Originally Posted by EngineerMike

Cummins also claims a higher h.p./displacement capability with SCR vs "in-cylinder" though it is impossible from their document to discern if that is effectively the same claim as the fuel mileage advantage, just said another way.

This is because the recirculated exhaust gas displaces a like amount of air that would normally be entering the cylinder as charge air. If the recirculated exhaust gas reduces the total mol weight of oxygen in the cylinder by, say, 8%, then that cylinder can only make 92% of the power of the same displacement cylinder with no recirculated exhaust gas. Therefore, in a given displacement cylinder, the less recirculated exhaust gas that is present (another way of saying the more oxygen that is present), the more fuel that can be burned and the more power produced.

With higher recirculated exhaust gas levels, displacement must be increased to produce the same power as a smaller displacement engine with less/no EGR.

Rusty

[DriVer]

Not for nothing BUT International Truck and Engine used a Cummins ISX in the HarleyDavidson LONEStar in my Blog.

Ok ... so can anyone explain what's going on with the sound test on this page? I think that quietier is better perhaps if you're trying to power a recreational vehilce.

Check it out HERE.

Check this out TOO!

Navistar's ITE has complete control over engines and tractor integration, they build the complete product. Do you see this as a plus for ITE?
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[Gary RVRoamer]

I think Mike has done a pretty well-reasoned and unbiased comparison.

The research I've done indicates that the Diesel Exhaust Fluid (urea mixture) costs about $3/gal in bulk (as a truck flee might have) and $6-7 per gallon in 1 gallon jugs at a fuel station (more likely what RVers will pay until DEF pumps begin to appear at truck stops). Cummins says a typical engine will use about 1 gal of DEF (urea mix) per 50 gal of diesel, so you might have to buy $12-15 dollars worth of DEF per 100 gallon fill-up.

The good news is that the 2010 engines are supposed to yield about 4-5% better mpg than the 2007 engine, a welcome change from the declines in diesel mpg we have seen over the last several years.

[RustyJC]

HERE is the American Trucking Association's take on DEF/SCR.

Rusty