TURBOS
Now we're ready to install compound turbos. We selected BD's product line initially because we wanted to test some of its well-known twins. We'll be using the BD R700 twin kit. BD created this kit for high horsepower towing applications and track use. BD uses a Borg Warner S400 with a 71.1 mm inducer for the larger primary turbo and a Super B S300 with a 57.1 mm inducer for the smaller secondary. These turbos will flow up to 1370 cubic feet per minute (CFM). BD's turbo engineers chose the components used in these turbos to provide the best performance possible from turbos this size. This compound kit was designed to provide efficient air flow for applications between 550 and 700 hp. We intend to tow large loads with a 450 rwhp setting and scale up to as much as 600 rwhp for daily driving and good wholesome fun.
However, our underlying goal here is to keep the LBMC reliable above all. If this truck is driven as a daily driver and used to haul 14,000-lb. loads across the country, we need to be able to trust it. This means low and manageable egts and a turbo kit that is trouble-free. These large turbos should be a good match for the fuel we'll be running. Also, Cummins introduced post injection cycles in this motor in 2005 to quiet valve clatter and improve emissions. Additional fuel is injected after the compression stroke, increasing egts significantly more than earlier 24 valve and common rail Cummins motors, which is another reason for us to use the larger R700 kit.
We'll begin our twin turbo install by removing the factory air box. Our new turbo kit will replace it.
Disconnect the batteries and remove the factory charge air tubes (before the intercooler).
Cut the coolant tube away from the mounting bracket at the rear of the engine block with a die grinder. The bracket won't be used.
Remove the stock exhaust manifold, turbo and downpipe elbow as one complete assembly.
Remove the plastic passenger fender well to allow access from the side to the lower half of the engine compartment.
Remove the hard tubing section of the heater core antifreeze supply. This tubing must be carefully bent to make room for the extra turbo. The tubing will be reinstalled and mounted to the secondary turbo bracket supplied in the kit.
BD provides a bracket to support the primary turbo. The mount attaches to the rear of the engine block. It's made of thin gauge stainless steel to allow some flex between the block and the turbos during high heat conditions.
Install the pyrometer sending probe fitting into the new BD heavy duty three piece manifold (included).
Mount the manifold to the engine block with provided gaskets.
Note: BD does not recommend that customers disassemble the turbos provided with the kit. If you allow a compressor housing to contact a compressor wheel, you may damage the compressor. However, in order to achieve a more precise installation, we carefully removed the compressor housing and cartridge from turbos and then mounted the exhaust housings. After the exhaust housings were mounted and torqued down, we reinstalled the cartridges and compressor housings, clocked them and fitted the boost tubing. This process allowed us to "fine tune" the install of the turbos, giving us some extra space to work with. Because we've got a lot more hardware getting stuffed into the engine compartment, it's important to take your time to insure that each piece lines up and fits perfectly. We've found this to be key in setting up a reliable, trouble free set of twins.
Leave all of the bolts on the turbo housings loose until the charge air tubing and hoses are installed and lined up properly.
After the turbos are installed, install the new oil drains. The freeze plug on the side of the block, near the oil filter, must be removed so an additional oil drain can be installed here. Tap through it with a screw, then remove it with pliers.