FOR IMMEDIATE RELEASE: November 16, 2010
Developing Clean Diesel Performance Parts
The new 6.6L Duramax LML is the cleanest and most powerful Duramax engine to date,
loaded with state-of-the-art engineering. Based on a theoretically ideal 90-degree “V”
configuration, it combines a cast iron block with aluminum cylinder heads, operating at a 16.8to-1 compression ratio. There are 4 valves per cylinder, and a variable geometry turbocharger
with an air-to-air intercooler. A Bosch high-pressure common rail system enables injection
pressures as high as 30,000 psi, allowing for very fine, precise fuel atomization through piezoactuated injectors. It’s rated to produce 397 hp @ 3,000 RPM and 765 lb-ft @ 1,600 RPM.
The engine exceeds the newest, most stringent federal and California state emissions
requirements by use of diesel exhaust fluid, which is injected to reduce nitrogen oxide emission
levels by over 60 percent compared to prior-year LMM engines.
The engine is housed in the 2011 Silverado, a pickup that has compared favorably to the
competition in recent media road tests and performance events, confirming that the engine
and powertrain is already very well designed for the purpose of heavy duty work. The question
is, can the Duramax be improved, and can it be improved without affecting the ultra-low
emissions performance of the vehicle, in the short or long run?
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It’s a difficult proposition, but the aftermarket industry is working on it, looking for
opportunities based on air flow improvement and taking advantage of the ability to control
nearly every system by computer. That’s not to say it will be simple. Electronic tuner specialists
have leaked word that the LML controller is so different from the LMM that it will likely be
many months before a selectable electronic tuning device will hit the market.
That still leaves possibilities for getting more air, and cooler air, in and out of the engine.
At Gale Banks Engineering in Azusa, California, upgrades are already in progress for the LML.
One area of opportunity is the air intake system. Air density can be improved by use of an
intake that improves airflow by means of a wider pathway and less restrictive filter. By taking
air from outside the hot underhood area, cooler, denser air containing more oxygen can be
accessed. In the end, the goal is to reduce EGT levels, or put another way, to increase power
potential at any given EGT level. Pumping losses can be reduced, so the engine does not have
to work so hard to breathe, creating the possibility of better mileage.
Developing an Improved Intake
Developing an improved intake is a process that starts with CAD design. To begin with,
the part has to fit perfectly in the engine compartment. Once exact dimensions are confirmed,
then computer simulations are used to compare different performance design ideas to the
existing air filter system. Using a technique known as Computational Fluid Dynamics (CFD) the
designer focuses on how the shape and volume of the intake affects air flow, taking into
(3)
account the available space, MAF (mass air flow) sensor placement and the need to gain
effective filter capacity. Eventually, a promising design emerges and a prototype is made.
That process, once a matter of shaping a part from metal, wood or other materials by
hand, is now much simpler and more exact. Using Rapid Prototype Machines, essentially a 3D
plastic printer, Banks engineers can view the CAD model, hit “print” and the machine builds up
a three-dimensional plastic part. If the part is very large, sometimes multiple pieces need to be
joined together to make the prototype, but even if that is the case, the prototype is available
soon after. The 3D printer is accurate to within 0.01 of an inch.
Once a prototype is made, it goes to the SuperFlow ISF-1020 air flow bench for testing.
The assembly is mounted on the bench, atmospheric conditions are recorded, and air flow
estimates are confirmed. At this stage, the output of the MAF sensor can be monitored using
an oscilloscope. It’s essential to see that the sensor outputs the same frequency as stock, at
any given flow level. The MAF element is sensitive to factors such as the thickness of the tube
and the angle it is mounted in sensor boss.
In the past, a small variance in MAF sensor output might not have been critical, but with
the LML and other clean diesel engines, it’s important to hit the number right on. Being a little
off in the MAF sensor potentially touches off a chain reaction, affecting EGR controls and other
critical emissions elements downstream of the intake. The Banks policy is to aim for 0%
variance, so that the installed part will never trigger a “check engine” light and log a code that
will have to be cleared later.
(4)
Real-World Testing
Once the engineer is satisfied that the new part will improve air flow without affecting
any of the other components, the part can be tested on an actual LML pickup. The test vehicle
goes to Banks’ chassis dyno, where the truck will be run through a cycle that confirms the
predicted performance outcomes. The truck is instrumented and data is recorded, looking at
factors such as vehicle load, mass air flow, EGR valve position, and many others. If necessary,
emissions testing can be done at this time as well.
In years past, before the advent of DPF-equipped diesels, that might have been enough
to send the part to production. But with a vehicle like the 2011 Silverado, which has sensordriven DPF cycles, it is still necessary to continue testing to observe how the new part affects
regeneration cycles. If a new part adds soot to the exhaust, for example, the diesel particulate
filter will need to regenerate more often, wearing out the particulate filter more rapidly and
causing fuel economy to go down. Ideally, a new part will actually reduce the need to
regenerate the particulate filter, extending its life and improving fuel economy, but in any
event, it must never cause extra regenerations. This can only be proven through extended onroad testing.
This “beta test” cycle involves installing the prototype parts on actual truck(s) for an
extended period of time—perhaps two months, over several thousand miles. During some this
time the truck will be driven normally, commuting, towing and hauling. In the case of an air
intake, the testing will also include worst-case, heat-soak testing in which the vehicle is loaded
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to its maximum, to study the difference between outside air temperature and the temperature
of the air at the turbocharger inlet. On-road testing continues until a series of regeneration
cycles have occurred. The LML Silverado, with urea injection, needs to regenerate somewhat
less often than prior Silverado pickups, so it takes more time and more miles to confirm the
suitability of a new part than ever. Currently, Banks has LML intake and exhaust prototypes
undergoing this type of final testing. It takes time, but in the end, the knowledge that the part
will perform and be compatible with EPA emissions, not to mention California regulations, is
well worth the cost.
Once final testing is complete, the part can be tooled and manufacturing can begin. It
goes without saying that the manufacturing process must conform to the tight tolerances
established in engineering. If, for example, the thickness of the material varies during
manufacture, or permits the part to deform under high vacuum conditions, those kinds of flaws
will negate the engineering work and create a part that could ultimately trigger alarms in a
LML-powered vehicle. It’s all part of the process that all aftermarket manufacturers will have to
adopt if they choose to work with the newest clean diesel engines. There will be some
aftermarket manufacturers who will choose not to invest the time or the equipment needed to
do it right, but at Gale Banks Engineering, it’s been part of the process for many years, so the
company has accumulated a large inventory of parts that improve performance without
affecting emissions levels or OEM emissions equipment. So there is reason to be optimistic
(6)
that, given time, there will be bona fide performance parts for clean diesel vehicles, offering
enthusiasts upgraded capabilities.
Even though development of an electronic tuning device for the LML is expected to take
some time, there are other types of performance enhancers that are likely to appear much
more quickly. Along with the Banks Ram-Air intake and Monster Exhaust, it’s likely that a
better-performing intercooler can be developed fairly quickly, further lowering EGTs and
reducing pumping losses, which relate to both power and fuel economy. Another opportunity
would be for an electronic brake controller that works with the LML’s variable air flow turbo
and electronic transmission, like the Banks SpeedBrake, to enhance towing control.
PHOTO CAPTIONS
1-LML
The newest Duramax, the LML, is more powerful and cleaner than any prior diesel. It’s also
more complicated, with an advanced emissions system that must remain EPA compliant. Some
aftermarket manufacturers will see that as a barrier. Others will see it as an opportunity.
2-LML
Creating a performance-improving part for the newest clean diesels will require careful design,
skillful engineering and precise manufacturing. At Banks, the process begins with CAD design,
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which allows an engineer to simulate and explore performance outcomes in a digital
environment. This particular design is for the 2011 Silverado HD Ram Air intake.
3-LML
Once a design is set, a prototype can be made. A rapid prototype machine, something like a 3D
printer, is used to build a three-dimensional model of the design.
4-LML
The prototype is fitted with a LML mass air flow (MAF) sensor and installed on a SuperFlow air
bench for testing.
5-LML
During testing, the output of the MAF sensor is monitored with an oscilloscope. It’s essential
that the sensor’s output match stock output at any given flow level, so that no “check engine”
light is generated. This type of bench testing will be followed by dyno testing and real-world
driving that allows the test truck to initiate several emissions system regeneration cycles. After
the part passes the tests at every stage, it can go to manufacturing for tooling.
6-LML
Not every part will require it, but more and more, emissions test equipment like this will be
needed to confirm that performance parts really will pass stringent emissions requirements set
by the EPA and state of California, without jeopardizing OEM exhaust treatment equipment.
(8)
7-LML
In the end, the new part becomes a performance product that clean diesel owners can use in
their vehicle with confidence. Other likely upgrades for clean diesel trucks like the LML
Silverado include upgraded intercoolers, cat-back exhausts, and electronic braking systems like
the Banks SpeedBrake.
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SOURCE:
Gale Banks Engineering
546 Duggan Avenue
Azusa, CA 91702
626-969-9600
www.bankspower.com