Today's newest emission-friendly trucks are most arguably better for the environment-depending on who you talk to, of course.
Thanks to Diesel Particulate Filters and regeneration modes, the new `08 model diesels run cleaner and are supposedly better for the environment than any previous diesel-powered vehicles. One thing that is overlooked in this "Think Green" mentality is that fuel mileage has taken a turn for the worse. Average fuel mileage from all three diesel truck manufacturers has gone straight to the gutter.
Restricting what a diesel engine can breath in and exhale out can have damaging effects on performance and efficiency, something that has become very evident in these new DPF equipped trucks. Case in point is the new 6.7L Cummins powerplant. While the 2007 5.9L Cummins could produce horsepower in the 325 range and still average 16-17 mpg in bone stock form, the new 6.7L has struggled to maintain 14 mpg and break that 300 hp barrier. More displacement but lower horsepower and lower efficiency? Thank you, EPA.
Enter Dynomite Diesel Performance (DDP), one of the biggest names in the aftermarket injector business. Knowing that keeping the factory DPF equipment and OEM electronics is a crucial part to keeping the 6.7L Cummins happy, DDP set out to find a way to accomplish two things: make more horsepower while improving fuel mileage, all while keeping the OEM computer and DPF happy, which in turn will keep the dealer and your local Subaru-driving-flip-flop-wearing enviro-friendly EPA man happy.
DDP has been in the injector business for years and knew some minor changes to the factory 6.7L injector nozzles could aid in performance and most likely improve efficiency as well. After speaking with Lenny Reed at DDP about the current situation with these emissions-friendly motors, he offered to let us test a set of his new 40 hp nozzles and swore we'd be happy with the results. DDP uses a very precise process known as Extrude Hone to enlarge the 6.7 nozzles, thus increasing the efficiency of the injector without creating more smoke.
We installed the nozzle tips on our stock injectors to see just how accurate DDP's claims really were and couldn't be happier with the results. Our test mule was a 2008 6.7L powered Mega Cab-100 percent bone stock. Before installing the injectors we made a few test passes on Custom Auto's portable Superflow dyno in order to get a baseline. With a peak of 298 hp, the 6.7L Cummins is still a very impressive powerplant for a stock truck.
Using the removal tool supplied by DDP we were able to make the nozzle swap on all six injectors in just a few hours, following its well thought-out instructions and taking care not to lose any small pieces in the process. One thing we should point out is, if you do this swap yourself, be sure each injector goes back into the cylinder it came from. The 6.7L is programmed to learn each injector and placing the wrong injector in the wrong hole could cause some serious headaches.
After making the swap and getting the truck back up and running we were once again off to Custom Auto to make some followup runs. On the first run we were surprised to see that DDP's claims of 40 hp were almost spot-on. With a peak horsepower of 343 hp, the nozzle swap picked up a solid 45 hp. It definitely offers an improvement in the seat-of-the-pants department. It's 45 hp you can feel while driving. The truck just seems to do everything easier. Acceleration is improved, throttle response is better and all around drivability is much nicer. The test truck tows a large gooseneck travel trailer, and the injectors made that task easier with better pulling power. The truck was able to hold a gear longer, taking strain off of the transmission.. Plus, our DPF is still running and working properly. The truck still runs as clean as it did with the stock injectors installed.
The most noteworthy improvement with these new DDP nozzles is the fuel mileage increase. While DDP claims the average owner should see 1-2 mpg improvements with its 40 hp nozzles, we can attest these claims are true. Our test mule has seen a consistent 2-2.5 mile per gallon improvement. Under the same driving conditions as before, mileage has definitely increased. With fuel prices as high as $4.70 a gallon, we'll take every mile we can get.
The Dynomite 40 hp 6.7L nozzle upgrade is a performance- and mileage-enhancing product that we'd strongly recommend to anyone in the market. We should also add that after our initial testing was complete we installed an AEM Brute Force intake system on our 6.7L Cummins and picked up another 18 hp on the dyno and some fuel mileage as well, bringing power output up to 361 hp and improving fuel mileage a consistent 3 mpg (another half to 1 mpg from the AEM intake) over our stock baseline.