Chevrolet 5.3L LS Budget Engine Build - 644HP Junkyard 5.3L

One essential key to making reliable horsepower with any type of power-adder is a colder-heat-range, nonprojected-nose spark plug. We used these Autolite AR474 race plugs to avoid preignition problems. These plugs use a very short ground strap with a short heat path to the head to avoid the glow plug problems with projected nose plugs that can cause preignition problems. A nonprojected-nose spark plug is essential for super- or turbocharged engines.

One essential key to making reliable horsepower with any type of power-adder is a colder-h

Centrifugal superchargers generally don't add dramatic torque at lower engine speeds, as was evident with this engine as well. Because our engine is only 325 ci, it doesn't make a ton of torque at lower engine speeds. In our case, it took until 4,700 rpm to make more than 500 lb-ft of torque, but considering we're talking about a 325ci engine with stock heads, a torque output of 1.68 lb-ft per cubic inch isn't bad. Our cast-piston short-block limited the safe boost to 12 psi and total ignition timing to a mere 22 degrees to ensure the engine would not experience detonation. The combination of detonation/preignition with cast pistons is a recipe for disaster, so we were conservative even with 100-octane Rockett unleaded fuel. We ran out of time to try a pump gas combination, but 18 degrees of timing with around 8 to 9 psi of boost would probably be safe and still make 590 hp. We'd suggest adding water injection to this combination just to be safe (see sidebar).

Test 1|
This was the normally aspirated baseline using a nearly stock long-block. The only real changes were the Comp hydraulic roller camshaft and matching valve-springs. We also added a Victor Jr. single-plane intake manifold, a Holley 750 carburetor, and a set of 13/4 to 17/8 stepped headers.

We used an MSD LS6 box to control ignition timing. It uses the factory cam and crank sensors to control the stock GM ignition coils. We used the MSD plug-in Curve 1 for the normally aspirated tests but set up our own custom curve for the blower tests by pulling out 2 degrees of timing around peak torque where cylinder pressure is the greatest.

We used an MSD LS6 box to control ignition timing. It uses the factory cam and crank senso

Test 2
This was the test for all the horsepower marbles. Using 100-octane unleaded race gas, the only addition was to hook up the ProCharger P1SC supercharger and a Quick Fuel blow-through 650-cfm carburetor. As you can see from the numbers, this was a huge improvement in power.