Rolf Lockwood

Most models won’t be on the street ’til near the end of the year, but Caterpillar’s
long-awaited new ‘EPA’ engines have now been formally introduced. Using what Cat calls Advanced Combustion Emissions Reduction Technology (ACERT),
they’ll replace the current ‘bridge’ engines that the company brought to market for last October’s Environmental Protection Agency emissions deadline. And none too soon. Those bridge motors don’t meet the new standards, and according to

EPA rules a fine must be paid on each one sold. Public records indicate that as of
March Cat had paid more than US$40 million in penalties on the non-compliant engines it had sold since last fall.

Cat says the new 2003 models will change that, though only one of them — the C9, first available last month — is so far certified and EPA- compliant.

In coming up with the ACERT designs, Cat’s engineers worked mainly on fuel and
air systems, while also re-working the software and adding exhaust aftertreatment
to meet the stringent 2002 EPA emissions limits. Most of the new engines have larger displacements and a fair bit of new hardware that varies from model to model. Judging by a couple of engines installed in trucks on display at the recent
Mid-America Trucking Show in Louisville, Ky., where the new lineup was introduced, in some cases there’s a fair bit of complexity under the hood — including a lot of hose/clamp joints — due to the use of two turbochargers in series on the heavy-duty models. Could serviceability be a challenge? We also noted the addition of a jacket-water aftercooler.

The 2003 Cat engine range includes the C7, C9, C11, C13, and C15 with power
ranging from 190 to 550 hp. See the chart below for basic specs and go-to-market dates. Availability ranges from June to December, while truck
makers are now working on the packaging and cooling issues.

Cat’s medium-duty C7, replacing the 3126E, gets a single turbo with electronic
wastegate. The 8.8-litre C9, a wet-liner engine with both front and rear PTO
capability, also has a single turbo. It has just two ratings for on-highway trucks — 335 and 350 hp — though there are also bus and RV ratings.

On the heavier side, the C11 will replace the C10 for vocational and regional
applications. Its displacement is 11.1 litres, up from 10.3 on the C10. The C13 gets a bigger oil sump and extra displacement — to 12.5 litres — and will take over from the current 11.9-litre C12.

The new ACERT C15 is the one that will interest Canadian fleets and owner-operators the most, and its ratings will range from 435 to 550 hp, with torque from 1350 to 1850 lb ft. Its displacement will be 15.2 litres, up from 14.6, and it features dual turbochargers in series like its C11 and C13 brethren. It’s the only overhead-cam engine in the group.

It’s not known exactly when we’ll get back to 600 horses and 2000-plus lb ft of
torque, and Cat didn’t say, but we gather that a ‘C18’ engine will replace the
discontinued C16 late in 2004. Its displacement will be a whopping 18.1 litres, we
believe, up from 15.8 on its predecessor.

All ACERT engines will be priced “at a premium”, the company says, but how much more they’ll cost the end user won’t be clear until truck makers have done
their installation engineering and established the databook details. In response to a question at the Louisville press conference, Cat did say the new engines are between 130 and 200 lb heavier than previous versions, though one competitor claims the actual figure is well over those levels in the C15.

Caterpillar uses a combination of new and existing technology in its ACERT engines, though details remain a little scarce. The mid-range C7 and C9, for
example, use proven HEUI fuel systems (hydraulically actuated, electronically
controlled unit injectors).

Heavy-duty models, on the other hand, use mechanically
actuated unit injectors. The C11, C13, and C15 depart from single-turbo tradition and use two wastegated turbochargers in series, part of what Cat calls an
“advanced air system”. It includes variable valve actuation controlled electronically, a design principle that the company has used in the past, to meter ncoming air precisely and optimize combustion.

The C11 and C13 also get a new cylinder-head design that allows for integration of an optional compression brake that’s said to be as much as 25% more powerful than previously. The electronic control module in charge of all this is the same one used before but it gets new software.

The other major change is that all ACERT engines require exhaust aftertreatment to reduce particulates. It’s the same oxidation catalyst that’s been used on Cat medium-duty engines for a few years, and on all ‘bridge’ engines since last October. It’s incorporated into the muffler. While it’s not likely to fail often, being a
simple piece of hardware, it’s also unlikely to be cheap to replace.

Cat claims that ACERT engines will be more fuel-efficient than those from competing manufacturers, all of whom use some variation on the exhaust-gas recirculation theme. But no testing supports this idea, at least none that Cat has shared publicly. There are relatively few ACERT engines in test service, though
there is one working in western Canada. Cat says it will have done 10 million test miles by October of this year.

Having dropped development of cooled-exhaust-gas recirculation (EGR) as its ’02 solution a couple of years ago, Caterpillar has since been very aggressive in
criticizing it, perhaps understandably. Claiming there would be reliability,
durability, and fuel-economy problems in EGR motors, as well as shorter oil-drain
intervals, Cat has been accused by some OEMs of souring the market and
contributing to slow truck sales as a result. In fact, only one of those criticisms
seems to have held up: fuel economy.

Led by Cummins, all other engine-makers — including DaimlerChrysler, whose
Mercedes Benz engines sold here will have to meet ’02 EPA emissions standards for January, 2004 — chose the EGR route and there are now many engines approaching the 500,000-mile mark in revenue service. Cummins, for
example, had sold almost 6000 ISM and ISX engines with EGR by mid-March, representing 45 million real-world miles, and Detroit Diesel about the same. By October, Cummins says it will have 25,000 EGR engines on the road.

Cummins, not incidentally, counters Cat by saying that EGR is simply a design
principle, a broad technology, and that there are as many ways to design it as there are engine makers using it. Its own variable-geometry turbocharger, for
instance, is distinctly different from that used by Detroit or Mack. Volvo uses a
conventional turbo, as does Mack in its vocational engines. The Cummins point is
that cooled EGR can’t be condemned in a blanket way.

So far the jury is still out on EGR in terms of longer-term durability, but Detroit says its own testing actually shows an improvement in both liner and ring wear in its ’02 engines — by a significant 49 and 78 per cent respectively — after eight million miles. There have been no reliability problems with any of the various EGR engines in service.

Heat-rejection horrors were anticipated a couple of years ago, but they didn’t
materialize. Nor have earlier fears about extreme soot-loading in the oil that
lubricates and cools an EGR engine — Chevron tests show no change in an ISX engine, for example. Only Cummins dropped its recommended oil-drain interval for normal duty, from 35,000 to 25,000 miles (all the others, Cat included, remain at 15,000 miles) but that may have been unnecessary in hindsight.

Fuel economy, which all EGR engine producers said would suffer, does appear to be poorer by 3 to 5% in most cases. Cat says its ACERT engines will achieve fuel efficiency on par with its 2001 engines, or 3 to 5% better than competing engines. Only real-world testing will prove it one way or another.

Caterpillar’s ace in the hole may be the next round of emissions limits that are due
to strike the industry in 2007. It says the same ACERT principles and designs
used now will be employed for ’07, meaning no major changes and a simpler
transition for both truck manufacturers and end users. But it’s not yet clear that
EGR won’t work.

Cummins, in fact, says its combination of cooled EGR and variable-geometry
turbocharging can meet the ’07 requirements with little change or new investment.

PACCAR and Cummins are already working to integrate systems, we understand.

For engine buyers, it’s obvious that much remains to be learned about EGR and
rather more about ACERT. From just a driver’s standpoint, we already know from our own testing experience that EGR engines either feel the same as previous models, or significantly more responsive when equipped with variable-geometry turbos. We’ll put a few miles on an ACERT engine as soon as we can.

Rolf Lockwood

Rolf Lockwood is editor emeritus of Today's Trucking and a regular contributor to

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