Cleaner Air And Fuel For Engine Longevity, Efficiency And Lowered Maintenance Costs

It’s hard to believe that it’s been more than 10 years since the GM LB7 Duramax was produced. As the first generation of the popular Duramax family, the LB7 continues to be one of the best light duty diesel engines out there. While it did have some issues with the injectors, it’s a solid platform for just about any application from the daily driver tow rig to an all-out competition truck.

1 The new line of Evolution air induction systems from Injen Technology offer a plastic injection-molded sealed box and high flow for incredible fit and function. When paired with the Deviant Race Parts High-Flow Turbo Intake Horn (lower right) it will offer better filtration with improved flow. The Deviant Cat Fuel Filter Adaptor will also be installed to replace the factory-style fuel filter to reduce future maintenance costs while improving filtration before the CP3 and injectors.

If the vehicle itself has been taken care of and regular maintenance has been carried out like it should, they can be great trucks to own even at relatively high mileage. With new truck prices cresting well above $50,000, it’s becoming more and more common for owners to hang on to their high-mileage trucks and start investing a little cash here and there to improve durability and performance alike.

“Injen chassis dyno testing showed a 21 horsepower and 46 lb-ft torque improvement…”

Case in point, this 2001 Duramax shows 276,000 miles on the odometer but is in great mechanical condition and does everything the owner, a cattle rancher and rodeo man, really needs. All summer long it’ll be found hauling horses around the Rocky Mountains to rodeos on the weekends and bringing 10 tons of hay out of the field on a gooseneck during the week. So it definitely gets used and abused in just about every road and load condition imaginable. Still virtually stock under the hood, it gets the job done.

There are, however, a few aftermarket parts that can be installed to help performance and aid in air and fuel filtration to extend the life of that tired LB7. The simplest modifications are usually the first to go on, but can be the most effective. The Evolution air induction system from Injen Technology along with a high-flow Turbo Intake Horn from Deviant Race Parts (DRP) reduce intake restriction to improve throttle response and performance while getting cleaner air to the turbo. And on the fuel side of things, converting over to a Cat Fuel Filter Adaptor kit, also from DRP, can help reduce maintenance costs while improving fuel filtration.


Injen Technology has been a driving force in the gas and tuner markets for years, but has recently jumped head first into the diesel market with their Evolution air induction systems designed specifically for Duramax, Power Stroke and Cummins applications. The sealed injection-molded plastic boxes fit the engine compartment perfectly while keeping hot under-hood temperatures from reaching the filter, making it a true “cold air intake.” The high-flow SuperNano-Web filters are dry filters that flow more air than stock while being easy to clean with compressed air. No more washing, waiting overnight for it to dry, and re-oiling as required when it’s time to service the filter.

2 With more than 275k on the odometer, this 2001 LB7 could definitely use a little TLC under the hood to bring performance up to snuff with today’s newest trucks. The truck is mechanically sound and does everything the owner needs, but the Injen Evolution can help that Duramax breathe easier while filtering significantly more of the dirt and dust from the back roads.
3 Comparing the factory intake to the new Evolution system, you can see how much better the large smooth radius ducting will improve airflow to the turbocharger. The big conical filter also offers more surface area for air to be filtered and ingested into the engine for improved throttle response, torque and performance throughout the rpm range.
4 Since the Evolution uses a sealed box to help keep hot under-hood temperatures from reaching the air filter, Injen includes a small suction tube that will run from the air filter to a filter minder mounted on the outside of the box. The filter minder will help owners know when it’s time for a filter service and cleaning.
5 With the air intake system off the truck, you’ll get a good look at the factory cast aluminum turbo inlet horn. While the horn shows a large near 4-inch diameter at the inlet side, it hides its pitfalls well as it necks down to just 2 ¾ inches on the exit where it mates up to the turbocharger inlet. This is the perfect time to swap it out for the high-flow intake horn from Deviant Race Parts.
6 & 7 With the factory horn removed you can see the true difference between the factory cast unit and the new DRP fabricated high-flow unit. The large-bore diameter stays consistent from end to end on the DRP piece, while the stock unit bottlenecks down. You can also see that DRP takes the extra step to aid in installation by slotting the lower mounting bolt holes. This allows you to start those hard to reach bolts into the turbo before slipping the horn into place.

Along with better flow and cool dense air, the cleanable filter can cut long-term maintenance costs as you’ll never have to buy another filter again; just remove the conical filter and blow it out with low-pressure compressed air and you’re back up and running again. On the LB7 application, Injen chassis dyno testing showed a 21-horsepower and 46 lb-ft torque improvement (43 hp/83 lb-ft on 2008-2010 LMM Duramax) so not only will you get better airflow and filtration to that hungry turbocharger, you can expect and modest increase in performance as well.


With a better air box under the hood, the last bottleneck in the intake system is the factory turbo intake horn that connects the air box to the turbocharger. The factory cast aluminum piece has a large 72mm inlet diameter but necks down to just 61mm at the turbo compressor flange. To reduce restriction before the turbo, Deviant Race Parts (DRP) offers an inexpensive high-flow mandrel-bent turbo intake horn that maintains that large 72mm diameter throughout.

The new DRP horn will help improve turbo spool-up, throttle response and overall turbo efficiency. DRP tells us you can expect a moderate 5-10 hp increase depending on your truck’s current modifications. Installation can be a bit of a challenge due to the location of the three mounting bolts and the tight working space, but with the right combination of extensions and universal joints on a ¼-inch ratchet it’s possible.

8 The completed Evolution induction system has near perfect fit and finish. The closed sealed box will help keep under hood temperatures from reaching the filter and the easy to read filter minder lets owners know when a filter cleaning is needed. Injen’s chassis dyno testing showed 21 hp and 46 lb-ft torque gained on an otherwise stock LB7.­
9 While the factory fuel filtration system works okay at filtering the fuel, the high cost of replacement filters keeps most owners from changing the filter every 10,000-12,000 miles as suggested. To help combat this, DRP offers a thread on Adaptor that will allow the use of a much less expensive Caterpillar 1R-0750 filter.
10 The Cat filter offers great flow with minimal restrictions and 2-micron filtration compared to the 8-10 microns of a stock filter.


The factory fuel filter on the GM Duramax located on the passenger side of the engine works pretty well at keeping clean fuel flowing to the CP3 pump and injectors, but expensive replacement filters can be tough pills to swallow when it comes time to change it. As the miles add up and the filter starts getting dirty, flow through the filter is reduced and engine performance and fuel mileage can be affected, sometimes bad enough to throw a check engine light that creates a reduced speed or “limp” mode.

11 The custom-machined Adaptor has the same internal threads as a stock fuel filter, so it simply threads right onto the factory base. While the bottom side of the filter has a machined external thread to accept the new Cat spin-on filter. Once the Adaptor is installed, it can remain in place for all future services; you’ll just need to swap the filter itself.
12 To help make the filter service even easier, the Cat Filter Adaptor kit from DRP includes this handy little spacer to move the filter base away from the engine. This added clearance gives you just that much more room to get your filter wrench or hand around the filter. Simply remove the stock bolts and discard, start the new bolts into the filter head, slide the spacer into place and finish tightening the bolts.
13 Here’s the completed Cat Adaptor installation. Replacement filters can be purchased for just $20, so it only takes two or three services to get your money back on the initial purchase, plus you can rest at ease knowing the CP3 and injectors are getting quality clean fuel.

The factory fuel filter on the GM Duramax located on the passenger side of the engine works pretty well at keeping clean fuel flowing to the CP3 pump and injectors, but expensive replacement filters can be tough pills to swallow when it comes time to change it.

The DRP Cat Filter Adaptor kit for 2001-2010 Duramax is a great way to reduce maintenance costs and improve flow to the engine, while getting better filtration at the same time. With just a $20 fuel filter to be changed, there will no longer be reason to avoid regular filter changes (8,000-12,000 miles). The 1R-0750 Caterpillar filter will filter down to 2 microns, which is much better than the stock 8-10 microns. Better filtration will reduce particle size getting to your pump and injectors, hopefully extending their life even further. Best of all, the filter Adaptor threads right onto the stock filter base and includes a spacer that moves the filter away from the engine to make changing them even easier. DW

Injen Technology


Deviant Race Parts

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