The need for more horsepower and torque is felt by many diesel enthusiasts. This drive is the reason we have a $1 billion aftermarket industry that's continually growing. While many enthusiasts feel that an intake, an exhaust, and a chip or programmer modification fill their need, there are those who still have the desire for more power. Once the basic modifications have been done, some enthusiasts start swapping or modifying the hard parts. Hard parts are things like injectors, injections pumps, pistons, camshafts, heads, connecting rods, and turbochargers (one of the most popular additions).
We recently had the opportunity to follow George Ward from Central Motive Power in Denver through the installation of a Garrett PowerMax dual ball-bearing turbo system on a Duramax LB7 engine. The Garrett dual ball-bearing design is said to spool up faster, respond quicker, and use less lubricating oil, which helps reduce seal stress and lessens the chance of turbocharger failure.
In the case of the '02 Chevy Silverado test vehicle we were working with, the stock engine produced around 279 hp when it was first dyno'd at 150,000 miles. After the stock numbers were recorded, we added a Banks Six-Gun tuner and a 4-inch exhaust. The new dyno numbers increased to 360 hp. The Garrett GT3788R turbo we were going to bolt on is capable of supporting 500 hp, which should be more than enough airflow to burn all of the fuel we were now putting into the engine.
Driving ImpressionsThis installation is not for the faint of heart. Our installer was quite annoyed by the lack of space available between the firewall and the engine. This installation took a total of two long days. In our opinion, this is a turbo kit that should be installed by a professional. While it is a direct bolt-on replacement, the back exhaust bolts are extremely difficult to get off, and making sure everything is back together and tight is difficult.
The truck has 150,000 miles and has always run pretty well once it got going. The boost used to be quite sluggish thanks to the altitudes where the truck spends most of its time (Denver area). The truck has a Banks Six-Gun that was installed more than a year ago, and depending on the setting, this truck used to run out of air before it would run out of fuel at the higher power levels.
After installing the new PowerMax turbo, the difference was instantly noticeable. The seat-of-the-pants feel told us this truck has a lot more horsepower-and that was before we started adjusting the wastegate. The response of the GT3788R is quite impressive and much better than the factory turbo, not to mention the boost comes in much sooner and remains strong throughout the entire powerband.
After a couple days of tuning the wastegate and cranking the boost pressure up to 26 psi, we ventured back to the dyno to see what the end results actually were. The truck now has more than 447 hp at the rear wheels. All this and the new turbo managed to clean up the black smoke the programmer was putting out on its highest setting while keeping our EGT below 1,300 degrees F.