Dodge Engines: What Makes a Hemi a Hemi

 by Ronnie Tanner

426 Hemi Engine

426 Hemi Engine

The hemi engine is an internal combustion engine built by Chrysler. The Hemi engine derives its name from the unique shape of its combustion chamber; it is bowl shaped or hemispherical, thus the name Hemi.

This half sphere design permits the valves to be angled rather than side by side. It also utilizes two valves per cylinder. The extra space created also allows for larger valves to be utilized and straightens the flow of air through the cylinder head, significantly improving the engines breathing capacity which can result in a higher power output from its given piston displacement.

The shape of the combustion chamber also cuts down on surface area maximizing the engines thermal efficiency. Fuel nearest the head walls tends to cool rapidly and is left unburned. Surface area is substantially decreased inside the Hemi combustion chamber therefore the fuel inside the chamber remains a higher temperature allowing a more efficient burn off of all available fuel.

The first Hemi engines were produced by Chrysler from 1951-1958. The Hemi was revived by Chrysler in 1964. When the Hemi took the top three spots at the 1964 NASCAR Daytona race, Chrysler decided it was time to go public once again. An old racing cliche states "Win on Sunday, sell on Monday" meaning that whenever a particular engine or vehicle wins a race on Sunday, sales of that vehicle tend to go up the following week. Looking to capitalize on this, the 426 Hemi was placed into consumer model vehicles and were produced from 1965 through 1971.

The fuel crunch of the 70's hit the sales of the hemi hard and was discontinued for sale to the general public. However in 2003, Dodge breathed new life into the engine design. The 5.7 L engine was available in the Dodge Ram 2500 and 3500 as a replacement for the 5.9 L Magnum engine. Chrysler has made several revisions to the Hemi for 2009 and it will be available in the Dodge Challenger R/T as well.

The Hemi powered muscle cars of the 1960's and early seventies have collector status now. These restored mint condition rides command high dollar figures and it is not unusual to see them go for as much as $100,000 at collectors auctions. Those Hemi engines were considered the bad boy toys of that time period and there is much speculation that today's limited edition Hemi vehicles such as the Super Bee SRT8 chargers, the Rumble Bee, the GTX and the Night Runner will one day be collector's items as well.

About the Author: Ronnie Tanner is a contributing writer at He writes about used Dodge engines and choosing this as an alternative to costly car purchases.

Article Source: March 29, 2009

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