With our freshly prepared LB7 short block back from the skilled craftsmen at L&R Engines, we quickly set to work getting the engine back within the frame rails of our ’02 Silverado. While a lot of people claim it, ours truly is a backyard build. We grabbed our trusty engine hoist and with the help of a few family members easily swayed by a free lunch had the beautiful Duramax resting in its home in short order. From there the arduous task of dressing the engine began. Come along with us as we get the turbocharger, heads, and valvetrain set for the next chapter in this engine’s already storied life.
| Fresh from being assembled by the experts at L&R Engines in Santa Fe Springs, California, we had our LB7 short block on the hook before even removing the wrapper.
| Would you believe us if we said this engine has nearly a quarter of a million miles on it? It’s amazing what fresh paint and quality machine work will do for heavy old chunk of iron and aluminum.
| Since we were working with consumer tools and doing the work in a yard we opted to not fully dress the Duramax engine prior to slinging it into the truck. This saved us about half of the engine’s weight and made the process simpler overall.
| The easiest way to get a Duramax into and out of its host truck is to remove the cooling stack. GM designed the trucks in such a way that the entire core support is removable with the AC condenser, radiator, and intercooler still attached.
| Once resting comfortably between the frame rails on its Sinister Diesel engine mounts we quickly taped shut any open port to prevent debris from entering and rust from forming.
| We began reassembly by installing our new Fleece Performance Cheetah turbocharger. The first step before mounting the charger was to plug the old oil feed port in the block. This is done because the new turbo will receive lubrication and cooling from oil fed from a larger galley plug.
| To feed the aforementioned oil we removed a galley plug from the left side of the engine and replaced it with the provided fitting. There are several options along the rail to choose from, and after this photo was taken we moved ours forward several more spots, due to tight clearances at the rear of the engine.
| Lb7 Duramax Engine Turbo Oil Feed
| On the turbo side an AN fitting replaces the factory oil fill tube on the Cheetah’s S300 center cartridge. We coated the threads with ARP thread sealant to ensure a leak free future.
| Also before dropping the charger into place we swapped out the factory wastegate controller for a Banks Big Head. With a larger diaphragm and spring the Big Head keeps the valve seated longer allowing for peak boost to come on sooner and provides a better midrange torque curve.
| Another nice touch with the Fleece turbo kit is their oil drain tube. Unlike factory, this piece uses a rubber gasket to ensure a positive seal every time. Nobody likes an oil leak at the back of the block.
| The final step before bolting down the turbo is to reinstall the heatshield and torque down the oil drain tube. It’s worth noting that at the same time we installed the new CP3 pump from Industrial Injection at the front of the valley. Dropping the CP3 in took a little wiggling, four bolts, and about ten minutes.
| If you mess with AN fittings often and don’t have a set of nice wrenches for them go out and pick up a set of NOMAR AN wrenches from Heatshiled Products. They’re carbon fiber and they are not cheap, but damn they are nice to have.
| Aside from the oil feed line on top it would be difficult for the untrained eye to tell there’s anything going on here beside a stock IHI turbo. And that’s just the way we like it.
| With the turbocharger in place it was time to continue working up and out, with heads being next on the to-do list.
| Since our truck came with a munched head (and a really poor deck job to try and salvage it) we thought it wise to just replace both sides. Aiming for 650 hp meant that we didn’t need anything crazy, so a set of factory rebuilt heads from Freedom Racing Engines was just the ticket.
| Before the heads could be lowered into place the intake manifolds needed to be installed. After cleaning the manifolds and painting them with high-temperature ceramic engine paint we applied a liberal amount of RTV sealant to create the necessary gasket.
| Each head has a pair of studs to help align the manifolds while installing them. Care must be taken to lower the manifolds straight down and into place, as shifting them will compromise the seal.
| While the manifolds gaskets seated we turned our attention to the ARP head studs. While not explicitly necessary at the power levels we’re aiming for with Duramax engines, installing head studs on performance diesel engines is never a bad idea. Each stud was liberally coated in ARP assembly lube before making its way to the engine.
| We threaded each of the ARP studs into the block by hand to ensure no thread damage occurred. Each was snugged into its bore with an Allan wrench before calling the job complete.
| With the studs in place we carefully lowered our head gaskets into place. We opted for Mahle gaskets that we picked up from Summit Racing. It is incredibly important that these be installed on the correct side of the engine, as doing it backwards will impede an important oil passage.
| Next up, the heads were carefully placed on the block taking care not to damage either the heads of the studs in the process.
| With another liberal coating of ARP assembly lube we next added the washers and nuts to the respective studs along with the smaller upper bolts. The lubricant is necessary to obtain the proper torque on the studs.
| We finally got smart and taped a copy of the stud torque sequence to the core support. This took the guesswork out of which stud needed to be torqued next.
| The ARP studs are torqued to 125 ft-lbs and this is achieved by stepping up the torque in three steps. The smaller M8 bolts are torqued to 25 ft-lbs. Note the shop towels being used to prevent debris from entering the engine.
| Rocker bridges went on next. Each valve lifter actuates two valves by pushing on the bridge, which resides on the top of each valve stem. Orientation matters, and its important that each bridge is properly seated.
| Since we didn’t know our engine’s history (and found some inconsistencies between the pushrods) we opted install Merchant Automotive’s heavy-duty pushrods. Precision ground from chrome moly tubing, these push rods mimic the factory shape and size but with the added strength to endure higher boost and horsepower levels.
| With all sixteen pushrods in place we were able to drop the factory rocker arm assembly into place. These locate with dowel pins in the head, which ensures perfect alignment with the valves and pushrods.
| Keeping with the theme of replacing every bolt we can with the equivalent ARP part, we turned again to Merchant Automotive for their ARP rocker shaft bolt kit.
| The rocker shaft bolts were torqued slowly, alternating between bolts, to safeguard against potentially bending or binding the shaft.
| With most of the hard parts now in place, next time we’ll tackle the difficult process of wiring and plumbing. Stay tuned…