What makes this little 5.7 V-8 so potent?
It's more than just the Hemi heads. Chrysler has combined old school muscle with modern technology to provide a powerful and economical V-8 engine for both trucks and passenger vehicles.
We have all heard the hype and seen the cool commercials with the beat-up Duster, the new Hemi-powered truck, and even a front engine dragster sporting a first-generation Hemi, but does the new Hemi engine live up to our expectations? While we really doubt the 5.7 Hemi-powered full-size Dodge truck would smoke a front engine digger (even with the chute deployed), the 345hp rating did pique our interest. We know modern fuel injection and electronics can make a relatively small displacement V-8 far more efficient than a carbureted version, but we felt the power and economy this engine produces had to be attributed to more than computers.
When it comes to engines, we know the best way to see what makes them tick is to go inside and take a look. I must say, we were impressed by what we found in the latest version of the most powerful production V-8 in the world.
The rockers are mounted on dual shafts, and-due to the design of the Hemi-have quite an offset. The rocker shape appears it may limit spring choices for use with higher-than-stock lift cams. We're sure the aftermarket is already working on rockers to unleash more power from this potent little motor. | 
As noted in this picture, the electrode position of several plugs was less than optimal, indicating power to be had simply by indexing the plugs. Seems to us the heads have plenty of room to be machined for bigger valves. This is what makes a Hemi a Hemi-the hemispherical design of the cylinder head's combustion chamber. Note the efficient dual-plug-per-cylinder design and the closed-chamber design on each side of the plug. The added quench of the combustion chamber adds to the already detonation-resistant design of the Hemi head, allowing for more compression and lower octane requirements. | 
The new Hemi utilizes multi-layer steel (MLS) style head gaskets. These gaskets use the same technology as the Cometic pieces we use in our high-compression race applications. Head gasket blow-by or seepage is virtually eliminated by this technology, which sandwiches a coated steel shim between two uncoated steel shims. We've found this style head gasket to be the equivalent of O-ringing and grooving the block and heads. |
Any die-hard Mopar fanatic knows the prowess of the Hemi engine. The Chrysler engineers really did their homework when they designed cylinder heads utilizing hemispherical combustion chambers. As it turns out, the design created the most powerful internal combustion engines ever. The next time you see an NHRA drag racing event, take a look at the top two classes of Top Fuel Dragster and Fuel Funny Car. Regardless of the sponsor of the car or the body on the car, the powerplant is a Hemi. That's right, John Force's Mustang Funny Car is powered by a Hemi with the same design as the 426 version introduced by Chrysler in 1964, albeit with a few enhancements. Why the Hemi? It's the only engine that makes enough power to be competitive in drag racing's top classes. Does Chrysler's newest version of this engine live up to its name? If judged by horsepower and torque ratings alone, the answer is yes
While the combustion chamber is hemispherical in design, it does offer a small amount of quench area on either side of the two spark plugs. Combine this design with a quench domed-piston, and you have a recipe for power. | 
As we investigated the bottom end of the motor, we were impressed at the beefiness of the block and main cap structure. Notice that all five main-caps are the four-bolt, cross-bolted design. The second-generation Hemi also had cross-bolted mains, but only the center three. | 
To feed the engine computer necessary information, Chrysler utilizes a crankshaft sensor located at the rear of the block, as well as a camshaft sensor (shown here) located in the right side of the timing cover. A knock sensor is also utilized and will decrease total ignition timing by eleven degrees if detonation is detected. |