How Much HP Does A Cam Upgrade Add To A 5.7 HEMI?

Chrysler's third-generation HEMI engine debuted in 2003, continuing a tradition that extended back to the early 1950s. HEMI engines are named for the hemispherical shape of their chambers, which allows for more efficient combustion and bigger valves. The earliest third-gen HEMI displaced 5.7 liters and was used in '03 Ram trucks. It had state-of-the-art spark advance and fuel injection systems that made it more efficient than its predecessor, and a 2009 upgrade added variable valve timing (VVT) and displacement along with a redesigned intake manifold and cylinder heads. In the 2024 Ram 1500, the optional 5.7-liter HEMI puts out 395 horsepower, while the 2024 Charger's HEMI is good for 370 horses. 

There are several routes you can take if you want to increase the output of your HEMI engine, but replacing the stock mild cam with a hotter upgraded version is a simple way to add some horses to your HEMI. But just how much horsepower can you get from a cam upgrade to this engine, and how much will it cost in terms of time and money?

[Featured image by Greg Gjerdingen via Wikimedia Commons | Cropped and scaled | CC By 2.0]

Cams control how far the valves move and for how long they remain open with each stroke, and this can be varied by changing the size and shape of the lobes that lift the valves. Valve spring upgrades are usually done along with a cam swap to make sure the valves maintain proper travel and close properly.

Comp Cams sells several hot cams for third-generation HEMI engines, as well as valve springs, rocker arms, lifters, and pushrods. Most hot cam options for the 5.7-liter HEMI cost between $550 and $600. For example, a cam for VVT-equipped engines that provides 0.596 inches of lift for intake valves and 0.582 inches of lift for the exhaust valves sells for $551.95 directly from Comp Cams. Intake lift of 0.05 inches is provided for 220 degrees of rotation for intake valves and 230 degrees for exhaust valves. 

MotorTrend's test team added a set of matching valve springs that sell for $340.95 at Summit Racing Equipment, and they saw an improvement of 67 horsepower from their stock measurement of 367 horses. Gains will vary based on the cam and springs used and the condition of the engine they are put in, but that's a reasonable estimate of what you can expect from a cam upgrade to a 5.7-liter HEMI V8. The $900-$1,000 estimate for parts is also a good yardstick, and you should expect the swap to take at least a few hours, even if you have experience with this particular job.