325 Chevy Small Block Engine - Bolt On A Cam And Heads And Add 120+HP

First off, how many engines can pick up almost 100 hp just from a cam swap? This reveals how good those stock 5.3L heads are, especially the exhaust ports. Combine a small displacement engine with decent exhaust and a relatively stout cam and the result is lots of engine speed. This package does sacrifice torque below 3,000 rpm compared with the base engine, which means this engine would be better matched with a manual transmission or at least an automatic with a high-stall converter. Another important consideration is that a stock 5.3L bottom end won't live forever at 6,800 rpm, so save yourself the trouble of writing to us with that bit of wisdom. Clearly, to keep this combination together, the cam should probably be 5 to 10 degrees smaller on the intake side with a single-pattern design, which would help the bottom end torque and only cost perhaps 10 to 15 hp. Or you could add some forged pistons and rods and have a nice day. Either way, a 100-plus-horsepower gain is reason enough to celebrate. But as impressive as this is, there's a lot more left in this garden-variety truck engine. Next month, we'll push it even harder.

Go With The Flow
Flow Test 1
Stock 5.3L aluminum head
1.89/1.55-inch valves
60cc chamber
205cc intake port volume

Flow Test 2
West Coast ported Stage 1 5.3L head
1.94/1.57-inch valves
60cc chamber
209cc intake port volume

Flow Test 3
West Coast 5.3L CNC-ported Edelbrock
2.00/1.57-inch valves
58cc chamber
200cc intake port volume

By Jeff Smith

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