Truck & Off-Highway Engineering - April 2021 - 5

TECHNICAL INNOVATIONS

" We've met
the 90 percent
[NOx reduction]
target using an
off-the-shelf
aftertreatment
system. "

Larry Fromm, EVP and chief commercial
officer at Achates Power.

CLOCKWISE FROM TOP LEFT: ACHATES POWER; ACHATES POWER; SPC. DARRICK FRITZ VIA WIKIMEDIA

volume of the engine and cooling system in half. The engine
enables faster, more fuel-efficient vehicles with longer range.
It helps their ability to engage and evade the enemy.
Would Cummins be the manufacturer?
That's up to the Army to decide. Our business model is not to
manufacture engines. It's to work with established engine
companies and license our technology to them. That's exactly
what we're doing with the ACE project with Cummins.
Achates is doing design and development for the family of
smaller-displacement engines for tactical vehicles, rated from
300 hp to 500 hp [223 to 373 kW], ourselves. We expect
Cummins or another engine OEM will come aboard on that one.
Achates also has a program with CARB.
That's right, it's largely funded by California's Air Resources
Board. This is the Heavy-Duty Diesel and it's the next one
most likely to go into production. We're partnering with
Aramco on this project. It's a 10.6-L, 400-hp [298-kW] diesel
designed to replace a 13-L truck engine. In August 2020, the
state enacted legislation requiring truck engines to reduce
their NOx by 90 percent. That's a huge leap, and difficult to
achieve. The Engine Manufacturers Association stated that it
would cause the cost of a diesel truck to increase by $58,000.
But we've met the 90 percent target using an off-the-shelf
aftertreatment system. We started out with a close-coupled SCR
[urea injection] and kept working on combustion-side improvements to the point where we didn't need that type of SCR.
The second ARB project goal is lower CO2, to meet the
EPA's Greenhouse Gas-II regulation for trucks. That one requires steady reduction of CO2 by 2027. Well, we're already
4% below the 2027 standard.
What's the status of the OP engine for pickups?
That's our third big project: the 2.7-L, 3-cylinder opposedpiston truck engine that's funded by the Department of
Energy's ARPA-E [https://www.sae.org/publications/magazines/content/17autp02/]. We finished the first stage of that
TRUCK & OFF-HIGHWAY ENGINEERING

Achates achieves low-NOx
engine-out emissions through
precise control of cylinder scavenging.
project, running gasoline compression-ignition. It's installed in
a Ford F-150. At the moment it's about 10 percent more efficient, on a drive-cycle basis, than Ford's most efficient engine in the F-150.
Gasoline is hard to combust at low temperatures, but the
OP engine can run compression-ignition with gasoline without any additional heat source. We can control the degree of
cylinder scavenging; at low loads we keep most of the exhaust gas in cylinder. This has a double benefit: it keeps the
trapped gas hot for stable combustion, with inherent NOx
mitigation because we have internal EGR. So, the OP is the
perfect architecture for low-reactivity fuels as we look to cooptimize engine and fuel with Aramco.

The U.S. Army is testing a 1,000-hp variant of Achates' Advanced Combat
Engine in a Bradley Fighting Vehicle. The Bradley's standard diesel is a
600-hp Cummins VTA-903A.
April 2021 5

https://www.sae.org/publications/magazines/content/17autp02/

Truck & Off-Highway Engineering - April 2021

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