Drivability & Efficiency Enhancements

Part One: Drivability & Efficiency Enhancements

A one-ton truck was really designed to have only one purpose in life…heavy hauling and hard work. Big crew cab duallies aren’t really what would be considered convenient daily drivers for dropping kids off at school or swinging into the grocery store for a jug of milk, it just isn’t their forte. Whether it be a welding rig along some Dakota pipeline, hauling hay around the Kansas farm, these trucks need to be able to handle a load and do it efficiently.

The first pile of parts to be installed this 2003 dually Duramax will really improve the overall drivability and efficiency of the fuel filter and air intake tract. Custom engine and transmission tuning from Duramaxtuner.com, Allison Tapshifter kit and Throttle Sensitivity Booster from BD Power and the 0 Cat Fuel Filtration kit and High Flow Turbo Inlet from Deviant Race Parts.
The SPADE tuner from Duramaxtuner.com came pre-loaded with their JACK tuning software with five on-the-fly adjustable power levels and a custom transmission calibration to help keep the LB7 within its peak power and torque curves while daily driving and towing. With the stock Allison transmission still in the truck, power gains are limited to around 100hp to ensure there will be no slippage or potential harm to the clutches and torque converter.
To be able to access all five power levels while driving, the supplied EFI Live DSP5 switch will need to be hardwired into the trucks engine control module. The large ECM connector will need to be disassembled and the two wires will need to be inserted into the connector. Step by step instructions are included, but a short install video on the Duramaxtuner.com YouTube channel can also help guide a novice through the installation.

This particular LB7 Duramax 3500HD Silverado project build is going to help showcase some of the best aftermarket equipment out there to help you get whatever job you need done. Over the course of the next 5-6 issues, you can follow along as this nearly stock 68,000 mile Duramax is converted into the ultimate towing and work rig. Recently purchased from a government auction, this once high school Agriculture Department truck had been used to haul FFA and 4H kid’s livestock animals to county fairs all around the state of Utah. In relatively good shape, the new owner soon added a 4” Flo-Pro downpipe back exhaust, S&B  cold air intake and Edge CTS Insight monitor. These basic parts make great first additions, allowing the Duramax to breathe better and allowing you to keep an eye on fluid and Exhaust Gas temperatures while towing.

ECM/TCM Tuning

Custom engine and transmission tuning from Duramaxtuner.com was the next thing to find its way onto the truck, as the additional horsepower and fine tuning of the transmission will really help get a heavy load moving and keep the truck in the proper power band over long grades. Using the EFI Live software and their Jack Spade tuner, the custom programming offers five tunes (up to 100hp over stock), which are adjustable on the fly  via the DSP5 switch installed on the dash. The custom transmission calibrations will hold a gear longer into the RPM range and allow earlier down shifts, which will aid in heavy towing situations. Under normal driving conditions, an owner can expect to see moderate fuel mileage gains as well.

Turbo Inlet Horn

Since this truck will be limited to around 400 rear wheel horsepower, due to the stock Allison transmissions limitation, the factory IHI turbocharger should be sufficient for this build, but improving the intake and exhaust systems will definitely help its overall efficiency. To go along with the S&B cold air intake, a high flow turbo inlet horn will replace the factory cast piece, which necks down, disrupting the ease of airflow into the turbochargers compressor wheel. Deviant Race Parts offers a nice fabricated and powder coated elbow that maximizes flow, which will produce quicker spool-up and improved turbo efficiency.

Luckily, the ECM has each specific pin location in the connector numbered, which will help in identifying the correct pin location for the DSP5 leads. On this LB7 model, pin 69 and 49 are used. LB7 owners also have the choice of selecting power levels through an Edge Products Inisght monitor instead of the hardwired switch, this would need to be mentioned upon ordering your custom tuning.
The factory LB7 turbocharger has been known to produce north of 500hp, so for our hopefully 400hp truck, it should be more than sufficient for the owner’s needs. But removing the restrictive stock intake horn will definitely help it get all the air it can take, which should improve throttle response and spool-up time.
The intake horn is held in place with just 3 small bolts, which can be a bit tricky to get to without the proper wobbly sockets and wrenches. However, the swap should take less than an hour. Once the stock cast piece is off the truck, you can see how much larger the Deviant Race Parts piece is inside, better airflow and less restriction means a happier more efficient engine.

Throttle Sensitivity Booster

To help improve turbo response and pedal feel, the BD Power Throttle Sensitivity Booster will increase the throttle percentage signal being sent to the ECM for a better pedal feel, improving off idle response and turbo spool-up. The module allows the driver to set its desired input and is a simple plug n’ play install.

Fuel Filtration

The factory fuel filters on the Duramax engine can be extremely expensive to replace and only offer 8-10 micron filters. Since the LB7 is known for injector problems, better filtration can really help increase the longevity and reliability of the high pressure fuel system. To aid in filtration, Deviant Race Parts developed a billet adapter that will thread right onto your factory filter base and allow the use of a better quality and cheaper 2-micron Caterpillar brand filter. Better filtration without restricting flow to the CP3 and injectors is a win-win situation, right?

Manual Transmission Control

The 5-speed Allison never came equipped with the manual shift option like the later model 6-speeds have, but the Tapshifter kit from BD Power can offer complete transmission control to aid in heavy towing situations for the LB7 and LLY applications. The Tapshifter kit, uses a small underhood module to piggyback the factory TCM and an OEM 6-speed shift lever with the manual select toggle switch to allow the driver total control of upshift and downshift patterns, allowing you to maintain one gear, much like a manual transmission truck would. This will help with trailer control on downhill grades holding for better holdback power and better uphill performance as the transmission won’t be hunting for that perfect gear all the time.


This small list of parts are great first steps in turning your current truck into a more capable towing and work truck, offering better performance, mileage and reliability all of which can help make for a better driving experience. Getting any job done easier and more efficiently is the main objective here, in next month’s part of the build, we’ll be improving usability around the farm with a Bradford Built work bed and Titan in-bed Hammerhead Transfer tank and Toolbox combo. DW

To help with the off idle response, the BD Diesel Throttle Sensitivity Booster kit can really help get a heavy truck off the line. By just altering the throttle pedal’s voltage signal being fed to the engine control module, the truck should have much better response for better drivability, whether towing or not.
– The Sensitivity kit will need to be calibrated to the trucks throttle pedal, so the module will need the outer shell removed to access the program and setting switches. The kit has three levels with Stock, Low and High being available per each driver’s personal preference.
The Sensitivity Module installs in just a matter of minutes by piggy-backing into the throttle pedal connector under the dash. Once the harness is all connected, a few simple steps to calibrate it to the pedal, and you can reinstall the cover and zip tie the unit up under the dash.
The factory fuel filter located on the passenger side of the engine keeps debris out of the CP3 and injectors, but the filters are expensive and some fine particles can still sneak through it. For better filtration, better flow and less expensive servicing, Deviant Race Parts offers an adapter kit so a Caterpillar 2-micron filter can be used.
The custom machined and anodized filter adapter threads right onto the factory filter head in place of your stock filter, then the CAT filter can be threaded onto the adapter. This system also includes a spacer and billet bleeder screw for easier filter servicing.
– The 2-micron CAT filter is much cheaper than the factory AC Delco fuel filters and will remove much smaller particulate in the fuel stream without limiting flow to the CP3 and injectors.
To further improve the 2001-2004 LB7 towing ability, BD Power developed a Tapshifter kit like used in the 2006+ GM trucks so the driver can have total control of the transmission shift strategy, just like if it were a manual transmission. The kit will plug direct into the factory TCM located on the driver side inner fender well.
The TCM connector will need to have the red cover removed and replaced with the supplied blue cover. The stock harness will then plug into the BD module which will work in series with the TCM to send/receive signal from the soon to be installed TapShifter lever in the cab.
The stock connector from the trucks wiring harness is on the left and the new BD harness is on the left, once these two connections are made at the BD module, the lever can be installed and there will be complete control over the transmission at the push of the paddle switch on the shift lever.
The stock shift lever (above) and the new OEM 2006+ GM Tapshifter lever (bottom). The new lever will still allow you to use Tow/Haul as always, but the paddle switch will lock the transmission in the gear of your choosing and hold. No more gear hunting while towing heavy loads over grades.
Once the new shift lever is installed in the steering column, the wiring harness just needs to be connected. The OEM style connectors make this a complete plug n’ play installation.



BD Diesel 

Deviant Race Parts

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