So here we are in a new year and facing the reality of yet another new engine era. Order a medium or heavy truck now and it’s going to come with a new variation on the emissions theme, thanks to the U.S. Environmental Protection Agency. 

There’s really nothing new to report on the SCR vs. EGR front, however, aside from a couple of lawsuits. Interesting, but not germane to your information needs.

Otherwise, both camps seem to have hunkered down in nervous anticipation of what the market — namely you — will do in the next months and years. The truth is, having enjoyed a bit of a pre-buy in the last quarter of 2009 that saw them building trucks at capacity, truck makers are now expecting a ‘no-buy’ period through at least the first quarter of this new year.

THE NEW REGIME:

To recap, the new EPA regulations, by far the world’s most stringent emissions rules, take us to almost zero allowable nitrogen oxides (NOx) and particulate matter (PM) or soot. Specifically, 2010 engines can emit no more than 0.2 grams of NOx, which has been phased in since the 2007 regs, and 0.01 grams of soot per brake-horsepower-hour, unchanged from ’07. And for the first time there’s a requirement for on-board diagnostics (OBD) on diesel engines in highway vehicles grossing 14,000 lb and more.

These motors are as clean as you’ll ever see. Note that allowable limits in 1998 were 4.0 grams of NOx and 0.1 grams of particulate gunk. Which makes the improvement an almost total conversion, at least in terms of those emissions (there are others, of course).

It’s unclear what we’ll see next from the EPA.

THE NEW TECHNOLOGIES:

It’s well known that all engine manufacturers except International will use a combination of SCR and cooled EGR.

In most cases, though some lips are well sealed on such ’010 matters, SCR will involve slightly lower rates of EGR — meaning smaller air volumes are cooled and thrown back through the turbo than with ’07 EGR motors.

The addition of SCR aftertreatment means that less emissions-busting has to take place in the combustion chamber. It remains to be seen what this means in long-term practice but in theory it’s a good thing, one likely result being the near elimination of regenerations required in the DPF, or diesel particulate filter.

Volvo goes so far as to say its new engines won’t need regens at all. And all SCR proponents claim fuel-economy improvements compared to EGR-only diesels.

SCR systems demand the use of diesel exhaust fluid, or DEF, residing in a frame-hung tank that will have to be replenished about every second or third fuel fill-up. The system sends a precise amount of vapourized DEF along with the hot exhaust gases into a catalyst downstream of the DPF. A chemical reaction in there turns NOx into clean nitrogen and water vapour. DEF itself is not to be feared, an American Petroleum Institute certified product that’s stable and harmless.

The upsides of the SCR-with-EGR answer are the dramatic reduction in DPF regenerations and the promise — we’ll see — of fuel-economy improvements. The downside is added weight, some 250 to 350 lb, and the need to keep the DEF tank full. Plus a surcharge of $10,000 or so. 

Paccar’s MX in Euro trim

International, of course, has opted for what it calls “advanced EGR” and says the reason is that it’s simple and a known quantity. It demands that much more air than before gets shovelled back through twin turbochargers, so the air-management system actually looks complicated.

It remains to be seen what this does to the number of DPF regenerations required.

On the other hand, there’s less weight added to the truck and there’s no DEF tank to fill. You’ll see a hefty surcharge here too, though likely less than with SCR.

Drivers of both systems report no issues with either one, and in fact no change at all.

(Though, we did learn recently that Navistar is looking at SCR possibly for the future, albeit with a twist on the delivery mechanism of ammonia aftertreatment).

MISCELLANEOUS NOTES:

We’ll definitely see two all-new engines this year and possibly one more. First is the Cummins ISX11.9 engine, a compact, inline-six motor targeted at vocational trucks, day cabs, and emergency vehicles. Originally developed for the Chinese market, it shares all emissions componentry, including the common-rail XPI fuel system and electronic controls, with its big brother the ISX15. Ratings will likely go up to 425 hp and 1650 lb ft of torque, though Cummins hasn’t released them yet. We won’t see it until about mid-year.

Coming from PACCAR at some point this year will be the compact 12.9-litre MX based on an engine built from a clean-sheet design by the company’s European subsidiary DAF in the Netherlands.

A popular engine over there (I’ve driven it and was impressed by its smoothness and quiet), it was once to be built in a new plant in Mississippi. That plan has been at least temporarily mothballed so the engine we see here this year will be made in Holland. It will use SCR.

MX features include the unique design of the cylinder block and one-piece head which integrate as many pipes as possible in order to minimize the number of engine components. The camshaft is in the block, which gives low engine height, fewer components, and maximum integration of functions. It operates both the valves and the fuel pump. The high-pressure fuel-injection system is completely integrated into the cylinder block as well. Among other interesting details are the fully encapsulated electric cables and connections.

I’m told that both Peterbilt and Kenworth will also offer the Cummins ISX11.9 when it becomes available.

The third possible new entrant is the MaxxForce 15 from International. Based on the basic iron of the long-lost Caterpillar C15, it will sport fuel- and air-management systems designed by the engineers of Navistar.

Presumably it will also employ advanced EGR but, as previously mentioned, Navistar’s newfound interest in SCR, indicates that nothing is cast in stone there, I’d guess. We’re unlikely to see it this year, 2011 being a better bet.

The lack of a true big-bore diesel puts International in a bit of a hole until that 15-litre motor comes along, but its 12.4-litre MaxxForce 13 will fill much of that gap, the company says.

The latter engine doesn’t meet the 2010 EPA NOx standard presently, sitting at 0.5 grams instead of the 0.2 required, and there’s no public indication about when it will. But that’s perfectly legal in EPA terms because of emissions ‘credits’ accumulated by others in its engine family that have over-achieved on the dirty air front. It’s unclear how long those credits will last though. The company answers that by saying “a long time.”

That’s not the only thing that’s unclear about this new engine era.

Performance doesn’t seem likely to be an issue with ’010 motors but pretty much everything else has yet to be fully understood. Some engine manufacturers have done 25 million or more test miles, many in real-world service, while others have only accumulated a few million.

But nothing tests a technology like endless months of day-in, day-out slogging, so the jury will be out for some time to come. Call it years.