Make 800 HP With a Boosted 5.3

We all know how well the LS engine family responds to bolt-ons.

- Richard Holdener

We also know how well they respond to boost, so the obvious question, then, is how well do they respond to both? While the answer may seem obvious, there is much more to it. Suppose you upgrade your LS engine with a performance camshaft, aftermarket cylinder heads, or an intake manifold—or better yet: all three like we did to our test engine. Will the power gains offered on the normally aspirated engine carry over once you add boost? What if the camshaft is tailored more toward forced induction, or not? The same could be asked of the intake or cylinder heads. We didn’t know the answers to these questions going into this project, but we sure knew how to find out.

While the questions were simple enough, finding the answers required no less than four different engine configurations. The test would start with a stock (actually near stock) 5.3L which we ran first in naturally aspirated trim, then again with a single turbo system. After running those two configurations, we then replaced the stock cylinder heads, camshaft, and intake manifold with aftermarket versions, then ran the tests again—both naturally aspirated and with the same turbo system used on the stock engine. In doing so, we could compare the power gains offered on both the naturally-aspirated combo and on the turbocharged version.

To start, we used a 5.3L engine built by David Freiburger for an episode of Engine Masters on MotorTrend. Equipped with forged rods and pistons from Wiseco, we reconfigured it with a stock LM7 cam, the original 862 heads, and an early 5.3L truck intake and stock throttle body, a set of 120-pound Holley injectors and 1 7/8-inch long tube Hooker headers. Dialing in the air/fuel ratio and timing curve was a Holley HP management system. Run in anger with the stock heads, cam, and intake, the 5.3L produced 333 hp at 5,200 rpm and 359 lb-ft of torque at 4,400 pm. Now it was time for some boost!