The Cummins may be the true diesel among diesel fanatics, but there's nothing like the feel and sound of a compression-ignition V8.
Our latest in-house Duramax project has had us working a few different areas for horsepower. This big, black beast is a 2005 Chevrolet Silverado 2500 HD with the LLY version of the 6.6-liter Duramax diesel engine. Its transmission had already been upgraded with a Sun Coast Stage 4 kit. And the fuel system had been tweaked to provide more fuel to the rails via a modified single CP3 and PPE fuel pressure relief valve race plug. It also has slightly larger-than-stock injector nozzles that originated from Dynomite Diesel Performance.
But this setup was built for a turbo that was larger than the stock VVT charger, but not by a whole lot. What we were after was, as usual, more power. That would take a bigger turbo and some modifications to the fuel system. We started out the project in the August issue of Diesel Tech with the install of a Silverline 4-inch turbo-back exhaust. That exhaust system has proven to be a durable, well-built system that flows ample amounts of hot exhaust gasses and provides a toned-down, unique rumble for the Duramax.
CLEANER DIESEL, BETTER FUEL
Our next installation was an AirDog II fuel/air separator. What makes the AirDog II unique from other AirDog lift pumps is the adjustable fuel regulator. There is a small external screw near the pump that controls how much pressure the AirDog II pushes to the CP3. For our application, we needed it to push 150 gallons per hour at about 9 to 10 psi to the CP3, so that when we experienced heavy fueling at wide-open-throttle, upstream pressure to the CP3 would not drop to 0 psi. Should that happen, the lift pump essentially becomes a blockage in the fuel line, starving the CP3 and common rails for fuel.
Another aspect of the AirDog II that appealed to us is the way it utilizes the stock fuel pickup inside the fuel tank. With that feature, we didn't need to poke a hole in the fuel tank and drop in a suction tube. Suction tubes are great, but they can't pick up fuel at near-empty tank levels like the stock basket can and drilling holes in the fuel tank is always something we'd like to avoid on a daily driver. PureFlow Technologies, makers of the AirDog, recommends drilling two holes in the sides of the fuel basket so that fuel can enter the basket before the higher flow rates suck the basket dry. So you will still need to drop the fuel tank. The AirDog II also utilizes all of the stock fuel lines and connections for an easy installation.
Mounted to the truck, on the frame rail below the cab, the AirDog II is exceptionally quiet. We used a rubber pad between the pump housing bracket and the mounting bracket to further dampen noise and vibrations, but the pump itself hums at a very quite buzz. You cannot hear it running over the sound of the engine at idle. We've been in several trucks where that is not the case.
Why do you even need a lift pump like the AirDog in the first place? The benefits of the water and air separation are reason enough to install one on any truck. Diesel fuel, when agitated, has greater tendency to trap air (notice how it foams when you fill a fuel tank?) than other fuels. That air stays in the fuel all the way to the injector nozzles, where it affects the spray pattern and density of the fuel being injected. The AirDog removes the air (and any water) from the fuel and sends pure, clean diesel fuel to the injection system. That makes power and improves overall power train efficiency, resulting in better economy as well.
On the power side of things, a 500-horsepower truck can pull a lot of fuel. The CP3-style fuel pump is a suction pump. It is mounted in the valley of a Duramax engine and pulls fuel to itself from the fuel tank. It has to overcome the restriction of the fuel filter and the fuel tank's basket and fuel pickup assembly, not to mention about 10 feet of fuel line. That's a lot of work for the CP3, but it can handle it just fine on a stock engine. The hotter the tuning in the ECM, the harder the CP3 has to work to get fuel past those restrictions and turn around and push it into the fuel rail at 26,000 psi. Using the AirDog as a lift pump pushes fuel to the CP3 at about 9 psi (that pressure is adjustable on the AirDog II), so there's not chance of the CP3 running out of supply fuel and starving the fuel rail-a key power-loss factor in hot common rail diesels. The AirDog II is a no-brainer addition for all these reasons.
LIGHTS OF THE AURORA
We couldn't wait too long before we messed with the turbocharger. We turned to ATS Diesel for an Aurora 5000 charger for this Duramax project with installation help from Custom Auto. Many of you may be getting ahead of us and might be thinking that the Aurora 5000 is more of a racing turbo than a daily driver or towing charger. And that it might have boost capabilities that would exceed the strengths of the Duramax engine's stock head bolts and connecting rods. Certainly it could, with aggressive tuning. But you don't always have to build a race truck just because you have a big turbo. You can take a charger like this, match it with a semi-hot tuning map and have a reliable, powerful, usable truck with a very broad range of power. That was our goal. Did we reach it? Check out the dyno sheets and see for yourself.
We have been around several Duramax trucks running over 40 lbs. of boost and putting more than 600 hp to the rear wheels on stock engine hard parts. It's not widely recommended to take that chance on stock internals, but we feel safe with the Aurora 5000 on this truck with these fueling capabilities. And our confidence lies partially with the turbo and the T3 pedestal and partly with the EFI Live tuning (which we'll get to later). Basically, we're running this charger at about 80 percent of its capacity with tuning that maximizes its power output below 40 lbs. of boost pressure.
The Aurora 5000 is surprisingly quick-spooling for a compressor wheel and housing this large. The tight T3 pedestal creates turbine pressures that equate into fast spool-up. The end result is a quick truck that is fun to drive around town and at the track. And it handles towing without much worry. We recently hauled a 10,000-lb. trailer load from Spokane, WA, to Salt Lake City, UT, and back to Idaho Falls, ID, with this charger and a meaty towing tune. On flat stretches of interstate, the truck could maintain 80 mph at 1,000 degrees F on the EGT and about 12 psi of boost in fifth gear. We did have to keep an eye on the EGT gauge on inclines and manually drop a gear when the needle hit 1,250 degrees F and leave it there until the incline ended. Dropping out of overdrive would kick the boost up to 18-20 psi and bring egts back down to below 1,100 degrees F for the duration of the climb. When we were on stretches of highway where speeds were limited to 65 mph, the truck spent more time in fourth and egts hovered around 850 degrees F with the higher boost pressures. We never ran out of power in fifth gear, even with the heavy load. As you can see in the dyno chart from the towing tune, the engine builds power as it goes. There's just no point in stressing transmission shafts and running too hot EGTs when there's not a race to win.
We'll admit we were hesitant at first about throwing the Aurora 5000 under the hood of a truck we were relying on as a daily driver and towing vehicle. Some similar applications we've tested and ridden in seem to labor too much to light the turbo in around-town driving, especially if there's a trailer in tow. But the Aurora 5000 has been a pleasant surprise, performing far better in those conditions than we ever hoped it would. It's made the big, heavy truck a blast to drive and a mean one to pull up next to at a rural stoplight.
COOL AS SNOW
Heat is always an issue to consider, whether building a towing vehicle or a race truck. Heat robs power, wears components like seals, rings and gaskets, causes premature wear and can lead to catastrophic failure. The best way to combat heat is to decrease fuel delivered during combustion or increase airflow. But that is at the sacrifice of power. What we'd really like is a product that can battle charge air and exhaust gas heat while adding horsepower instead of robbing it. That product exists and it's found in a Snow Performance Water/Methanol injection system.
Powerlabs Diesel installed our Snow Performance Stage 2 Boost Cooler kit, with a seven-gallon reservoir for increased range on a vehicle that spends extended time periods on the road.
During some closely-watched testing periods with no load in or behind the truck, here's what we found. On uphill climbs at freeway speeds, the truck without water/methanol would pull the climb at 18 lbs. of boost and hold egt temps of 1,070 degrees F. With the Boost Cooler control set to start spraying at 12 psi and max out at 50 psi (which turned out to be about 6 psi above this truck's max boost), and the system on and running with a 50/50 blend of methanol and water, egts dropped to 990 degrees F and turbo boost increased to 22 psi (in the same gear as the test run without water/methanol). It makes power and provides a net decrease in exhaust gas temps, not to mention a drop in charge temp as well. Is the Snow Performance Boost Cooler system worth the money? You bet. Where else can you get more power and lower egts in a simple, easy-to-use package?
POWER FROM THE PC
We also took advantage of switching from a hand-held programmer to EFI Live custom tuning while the truck was at Powerlabs Diesel. We built five custom programs and installed a 5-position DSP switch for on-the-fly changing ability between the tuning maps. For the five tunes, there is one "stock" map, which uses the original LLY map with a little fuel pulled out to compensate for the DDP nozzles. The second tune is a towing tune, the third is a street driving tune (low smoke, but still quick), the fourth and fifth are both race tunes, with the fifth map having the most top-end fuel.
Custom tuning allows you to take the local altitude and specific driving habits and demands into consideration. We run between 4,500- and 6,500-foot elevations and do everything from midnight runs to Wal-Mart to 2.8-class sled pulls.
The dyno charts tell the story of what this package is capable of and the value of good EFI Live tuning. In the towing tune, the engine builds power in a long, steady, climbing line right up until the engine runs out of RPM. The truck runs as good on the road with a trailer as it looks on paper on a dyno. The same goes for the hotter race tune. Even though it runs out of fuel (purposefully), it maintains a broad power delivery range. Not a spike and a slow decline in power, but broad power that translates into useable power at the tires.
Since this is a truck and not a show car with an oversized trunk, it actually gets worked. Early on in the process, we spent some time in the Custom Auto shop installing a set of Firestone Ride-Rite air bag helper springs with the Firestone Standard Duty Air-Rite air system. The Air-Rite is an on-board mini-compressor with an in-cab switch and pressure gauge. You can monitor and adjust air bag pressure at any time from within the cab. We usually had Ride-Rite air bags on most of our trucks in the past, but this is the first time we've gone the extra step and installed the Air-Rite compressor. It is worth every penny, especially on vehicles that tow trailers or see payloads on a weekly or daily basis. We haven't had to touch an air hose and we love it.
CAN YOU BREAK A 20?
Normally, we care as much about wheels as we do stereo systems-in that if it doesn't make it faster, why do you want to read about it? However, a blacked-out Chevy like this one deserves a little flair. Mamba's Type M3 20-inch wheels gave the truck a finished look that we weren't getting with the all-black wheels we had on it previously.
We were originally going to run a set of Toyo Open Country A/T tires, but found some research indicating that diesel pickups get more miles out of a set of M/Ts. The jury's still out, but either way, a set of 33x12.50R20 tires are definitely not cheap. From a cost standpoint, going with the A/Ts would have saved us about $20 total, so we're glad we went with the M/Ts so far.
We certainly don't mind accessories that serve a valuable purpose. The Better Built crossover truck box has left us with a good impression. Unlike other boxes we've used that have wound up having latch problems or easily warped lids, this black diamond plate Better Built single-lid crossover box is tough as nails. We've loaded it with everything from fishing gear to tool sets and crammed it so tight with luggage bags on rainy trips that we had to sit on the lid to get it shut. We've cinched dirt bikes up against it and hit it with ATVs. In short, we've treated it the same as the rest of the truck-by beating the hell out of it. It continues to function as new, and the finish has held up great as well.
The Iron Bull front and rear bumpers really gave the Chevy a look of its own. The stout bumpers are available in several configurations, for winch setups or otherwise. A set of smoked Lightforce lights add the finishing touch.
We'll also get to a full DT Tested product review on this in a later issue, but we've also installed a Viper Electronics remote start/security system on the truck, although we went with the Viper 5901 system more for the remote start aspect, all of its features have proven valuable. The Viper 5901, installed by Ideal Audio in Idaho Falls, ID, is loaded with features that set it apart from other remote start systems. First, it has a 2-way responder so that you can read data on the LC3 key fob display. You can see if the engine is running and the time left before it shuts itself down; whether the vehicle is locked and armed or not; text displaying "door open" or "shock sensor" if an alert is sent from the vehicle and other display features. You can customize the 5901 system with timer starts, custom run times, runtime extensions, etc. Living a the cold region that we do, having a remote start system is almost a necessity. The Viper 5901 system is a luxury.
CSilverline Diesel Exhaust
Broadway Ford Body Shop
Dynomite Diesel Performance
Iron Bull Bumpers
Sun Coast Converters
Royal Purple Oil