The LS series family of engines from GM has proven to be one of the most reliable and powerful lines in the company’s history. Ranging from 4.8 liters to the almighty 7.0L found in the ZO6 Corvette, these engines have dominated the racing world for years. There are tons of aftermarket parts available to increase performance and power.

The LSX Dr. has built a custom engine for our company Silverado. The current engine is a 2007 5.3L, LY5. Stock horsepower (flywheel) is rated at 320HP and 340 lb-ft of torque. Typical loss figures through an automatic transmission are 18/20%. The goal of this project was to build a reliable N/A engine with increased horsepower and torque through the entire power band. This would be accomplished through a custom ground camshaft and hand ported cylinder heads. For our camshaft selection, The LSX Dr. called upon Patrick Guerra. http://guerragroup.com/camshaft_help.htm Patrick took the critical data we provided for our project and designed a new custom camshaft profile. This data was then sent to Geoff at Engine Power Systems http://www.engpwrsys.com/ where he coordinated with Comp Cams to get the camshaft ground. Specifications on the cam are as followed:

218/226 .595” / .598” 113LSA + 2 Advance

111 installed intake centerline Comp EPS/EPS lobes

The biggest part of this project was getting the cylinder heads ported, machined and assembled. (Casting #799) Increasing the flow and efficiency of the heads is necessary to take full advantage of the aftermarket camshaft. Extensive work was done to the intake, exhaust and bowls on both heads. They were then machined .030 which raised the static compression to 10.68:1. To finish them up, a 5-angle valve job was performed topped with Ferrea Stainless Steel Valves and PAC 1218 Valve Springs.

Before the heads were bolted on, the custom camshaft was installed along with new GM roller lifters. The stock 5.3 LY5 is equipped with Active Fuel Management. This disables 4 cylinders while driving under light load to increase fuel economy. All the components used for this system were removed and the ECU was reprogrammed to disable this feature. The LSX Dr. chose a camshaft with a 3-bolt core vs. the stock 1 bolt design. The stock spring loaded timing chain tensioner was discarded and upgraded with the stationary “wedge type”. GM#12588670

When using a 3-bolt core camshaft you will need a new camshaft sprocket. GM#12586481

The LSX Dr also recommends upgrading to an IWIS timing chain, available from Scoggin Dickey #SD3SR602. The last component needed to eliminate the AFM is replacing the center valley cover. GM#12570471

The cylinder heads were bolted up using factory GM head gaskets and ARP bolts. This combination has proven to be very reliable. Once the heads were torqued to spec, JBA shorty headers were installed.

Another cool and custom option The LSX Dr. added to this project was a 4 corner custom cylinder head venting system. The stock set-up only allows for venting on the front of the heads. The rear ports are blocked off. By venting all 4 corners this ensures there are no air pockets in the top of the cylinder heads. Air pockets can cause inconsistent cylinder head temperatures which can lead to detonation. Custom adapters are available from Kurt Urban. www.kurturbanperformance.com

To finish up the Valvetrain, The LSX Dr. installed a complete set of JESEL Sportsman Series Rocker Arms. These are the absolute Best LS Rockers in the industry. Full shaft mounted with roller tips, these rockers can handle all the lift and RPM you throw at them. The precision machining and attention to detail is amazing.

After all the technical work and research that went into this project The LSX Dr. had to give her some pretty colors. Traditional Chevy Orange and Aluminum were used. Topping off the cylinder heads are some hand made aluminum valve-covers with custom-made decals.

With the intake manifold bolted up, a new GM throttle body from a C6 Corvette was installed. The C6 T/B is a 90mm vs. 87mm from the Silverado. GM#12570790

An SLP 160° thermostat and 25% under-drive pulley were also installed in order to get every last horsepower out of this 5.3 Chevy.

Before dropping the engine back in, some transmission upgrades were in order. The first was a 3000-RPM stall converter from Rev Maxx. It was fitted with their upgraded Carbon Fiber Lock Up Clutch to handle the extra torque. The next was a larger transmission cooler. The stock unit cannot handle the extra heat generated by the torque converter. The LSX Dr. chose a 40K GVW cooler from Tru-Cool. This cooler can fit behind the stock grille using the factory bracket and will provide the necessary extra cooling to ensure the transmission has a long life.

One of the best feelings is a firm and positive shifting transmission. The best way to accomplish this is through mechanical upgrades and custom ECU tuning. Since our Project Silverado had the 4L60E there were many upgrades available. The LSX Dr. chose to install a Sonnax servo, spring and side cover upgrade. This provides additional clamping force to the drum and clutches to prevent slippage from the additional horsepower.

Everyone has his or her own opinion on how a transmission should shift. The LSX Dr. prefers a very firm, quick shift. I spent several hours on the dyno and driving with Justin from Black Bear Performance tuning the transmission. The key is using the right components and having a tuner who has the knowledge to make them all work together. www.blackbearperformance.com

A 4-cycle engine is basically an air pump. The more efficiently you can get air in and out the more power it will make. The LSX Dr. chose to use the intake system from Volant. This system is in my opinion the best on the market for GM Trucks and SUV’s. It is made from a plastic composite material; this helps to repel heat and is super durable. The air box is totally sealed from under hood heat and has a large intake port from the grille. This is great for cold air to get in going down the highway. The included air filter is a cleanable type that provides superior flow compared to the stock paper type.

The last component of this project is a Methanol Injection system from Snow Performance. The LSX Dr. installed a Stage 2 system with dual nozzle injectors. This system has a digital controller that uses the signal from the MAF sensor to control the injection flow rate. The injector on time can be set as well as the ramp rate at which injection flows. As air flow and RPM increase so does the amount of injected Methanol. There are several benefits to Methanol Injection.

• Naturally aspirated/stock compression:
With naturally aspirated engines using less than 10:1 compression, water/methanol is used often in warm climates to get the intake temps lower. Benefits include: 10-15 HP increases from air density increases and full timing as well as more effective air/fuel ratios, increased gas mileage, and carbon free combustion chambers.

• The extra 20-25 points of octane provided allows for more spark timing advance and a leaner air/fuel ratio with the use of a programmer. Both of these factors not only improve power; their efficiency gains improve mileage as well. Additionally, many modern cars will detect the combustion of the methanol and reduce the injection of gasoline accordingly through the adjustment of long-term fuel trim values in the vehicles computer. This can directly and positively impact gasoline fuel economy. Gains of 5-15% are possible depending on how the vehicle is tuned and driven.

The final result is one awesome Silverado! This truck runs and feels great. The key is using the right components and making them all work together. Final Dyno numbers were impressive for a little 5.3. Through an automatic transmission and a 20” tire/ wheel combination she pumped out 331 RWHP and 305lb-ft of torque.