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 16.8-

to-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 piezo-

actuated 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

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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.

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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 sensor-

driven 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 on-

road 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

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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-LMLThe 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.

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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