Chrysler’s 5.7 HEMI V8 has come along way from its basic roots in the 1950’s. And even saying that isn’t really fair as aside its basic design layout, it shares not a single part or bolt with anything dating back more than a decade.
As configured in the Chrysler 300, it has 363 horsepower and 394 pound feet of torque. It red lines at 5,800 rpm which is relatively low but it’s plenty happy to rev up to that point. And in this car it comes only with an 8-speed automatic transmission.
Modern technologies on the engine start with port fuel-injection of course. Air passes into a front-mounted throttle body into a long runner intake manifold similar to the one first seen on the 6.4 liter HEMI engines.
Further separating this HEMI from the 1950’s is its variable cam timing, which uses an oil-pressure controlled sprocket on its cam shaft to retard or advance timing depending on engine load and speed to give either more performance or increased fuel economy.
Backing up that technology is a Multi-Displacement system that also uses oil-pressure control to deactivate eight of its hydraulic lifters to shut down four cylinders during coast, cruising or other times when extra power isn’t needed.
In this mode, the valves are closed. No fuel, no spark, no combustion in the cylinders. When you roll onto the throttle it can fire them back up in as little as 40 milliseconds. It’s barely noticeable and Chrysler says the system improves fuel economy between 10-20 percent.
When you are demanding power, the HEMI V8 delivers on its name with hemispherical aluminum heads that while still only have two valves per cylinder, have two very large valves canted in a hemispherical combustion chamber shape.
Because there are two spark plugs per cylinder, firing them is a very unique coil pack that has two boots. This makes for a clean look up on top of the engine which is manufactured in Chrysler’s Saltillo Mexico assembly plant.
Looking around the engine compartment, notable is the fact that even though this is a large car, it’s still packed pretty tight. Things like access to the brake fluid reservoir are backed up under the cowl trim and the battery is located in the trunk – which is a good thing for weight balance.
Standing back and looking forward, you can see the front clip and radiator support is made of molded composite plastic to save weight. On it you can see the collection of brake lines headed to its ABS controller mounted up front on the passenger side.
Overall, regardless of which engine you find here, this is a cleanly laid out engine bay with most service points located in easy eyesight and placed such that you can get to them without too much brain damage.