2004 GMC Sierra Engine Upgrades - Comp Cams Valve Springs

Using the same valve spring tool, we installed the new COMP Cams valve springs onto the valves, along with new COMP valve seats keepers, locks, and valve stem seals. We followed the truck repair manual and measured the valve stem seals for proper positioning, but this proved our biggest mistake. We should have listened to our common sense and used a deep-well 9mm socket to gently tap them down for a complete seal.
Using the same valve spring tool, we installed the new COMP Cams valve springs onto the va
Factory LS-style rocker arms, as found on 4.8-, 5.3-, and 6.0L truck engines, don't handle high rpm very well and to prevent any failure, we upgraded our stock rockers by using COMP Cam's trunnion bearing kit. The old bearings needed to be pressed out, or in a pinch, they can be knocked out.
Factory LS-style rocker arms, as found on 4.8-, 5.3-, and 6.0L truck engines, don't handle
We purchased a press to make things easier, but you may be able to use a large bench vise to press the new needle bearings and rocker shafts in place. The bearings are secured with snap rings on each end.
We purchased a press to make things easier, but you may be able to use a large bench vise

It was now time to install the new COMP rocker arm studs. We torqued each stud to the recommended 22 lb-ft. The valve covers, with new gaskets in place, were then installed and the coil packs reinstalled.
It was now time to install the new COMP rocker arm studs. We torqued each stud to the reco
Almost finished with the install, we bolted the water pump back on, with new gaskets in place, and torqued the bolts to spec. The alternator was then bolted back on, along with the radiator, hoses, and new coolant added.
Almost finished with the install, we bolted the water pump back on, with new gaskets in pl
Sean, from SoCal Tuning plugged in his laptop and began the ECM tuning process, but we ran into our one and only problem. The valve stem seals didn't seat properly and our 4.8L was smoking. Keeping the tune very conservative, the rear wheels spun to 297 hp and 294 lb-ft of torque. Up 15 hp and 7 lb-ft of torque, our numbers don't represent the usual end results of a cam and tune install on an LS engine, but with the engine smoking, it was the safest route. We could have blown it up, but we chose not to.
Sean, from SoCal Tuning plugged in his laptop and began the ECM tuning process, but we ran

Wanting that ever-elusive 300 RWHP number, we gave the guys over at ASP Racing a call for one of their 23 percent underdrive kits. These kits include a new, smaller crank pulley/balancer, new alternator pulley for proper charging, and a GM crank bolt. This setup is usually good for 10-15 RWHP, so this should safely get us over the 300 hp mark.
Wanting that ever-elusive 300 RWHP number, we gave the guys over at ASP Racing a call for
We pulled the factory crank pulley/balancer the same way we did in photo 49 and side by side, the new ASP Racing pulley is about 23 percent smaller in diameter, allowing the crank to spin with less parasitic loss and freeing up some horsepower.
We pulled the factory crank pulley/balancer the same way we did in photo 49 and side by si
Using an air impact and a 15/16-inch socket, the old alternator pulley was busted loose and the new ASP pulley installed.
Using an air impact and a 15/16-inch socket, the old alternator pulley was busted loose an

The new ASP crank pulley/balancer simply went on with help from the new 24mm bolt and an air impact. We then torqued it down to the recommended 240 lb-ft. It took some serious pulling!
The new ASP crank pulley/balancer simply went on with help from the new 24mm bolt and an a
We were now ready to install the shorter serpentine belts. Thankfully, ASP did their homework and includes the belt sizes in the instructions, so we just went to the parts store and picked up the new belts.
We were now ready to install the shorter serpentine belts. Thankfully, ASP did their homew
Back on the dyno, our tired 4.8L made 306 RWHP and 301 lb-ft of torque. Despite the smoking, we made one more pull with the nitrous activated and saw the dyno spin up to 358 hp and 361 lb-ft of torque. That's some serious power for just bolt-ons and some go-juice. Be sure to check out next month, when we'll take Project Novakane to the next level.
Back on the dyno, our tired 4.8L made 306 RWHP and 301 lb-ft of torque. Despite the smokin

FROM THE DRIVER SEAT
There is a great deal going on in this story, and we wanted to show you the highlights. This is by no means a step-by-step or how-to story as it is more an overview of what and how we made our truck go faster. With that said, these parts shouldn't be overlooked as just go-fast, gearhead eye-candy. Each part installed steadily increased horsepower and the culmination of each part really turned our little 4.8L into a respectable street prowler. There aren't too many naturally aspirated 294ci V-8s producing more than 300 rwhp and we're proud to say this one does. Admittedly, 150,000 miles is a little late in the game to start squeezing horsepower out of a work truck, but it handled everything we threw at it without a hiccup. Our only areas of concern were the necessary fuel line fittings, hoses, and adapters that were required to make the new fuel rails work with the factory high-pressure fuel line. Also, the front steam line had to be replaced with a dealer part because of intake clearance. Lastly, we needed a shop press to install the trunnion bearing upgrade for our factory rocker arms and didn't realize it until everything was torn down. Thankfully, each challenge wasn't too difficult to overcome, thanks to Sweet Performance Products fuel hoses, a 6.0L steam line from a GTO, and the purchase of a press. Now that you know what we know, there shouldn't be any surprises if you follow our lead. We're happy to report our only shortcoming was following the truck repair manual's new valve stem seal instructions. We did what it recommended and slid them down the valve stem within a .712 inch tolerance rather than using a 9mm deep-well socket and tapping them all the way down the valve stem (which is what our common sense told us to do, but we didn't listen). Not every valve stem seal seated properly and after sitting for a couple of days, cylinders 5 and 6 were filled with half a quart of oil-bummer. Our engine was hydrolocked and rather than take it back apart, we're going to swap in a GM Performance Parts crate engine. Check out next month where we'll unveil the future for Project Novakane.