Hemi Engine History
It is crucial for us to know which Hemi engine is in your vehicle because there is more than one. (Sam of Century Performance Center, Inc provides this article.)
First, Some History:
Although Chrysler trademarked the term “Hemi” somewhere in the 1950s, it wasn’t until the second generation Hemi, the 426 that showed up in 1964, that Chrysler started using the Hemi term to officially define the name. The name originates from the hemispherical cylinder head and, more specifically, the combustion chamber design. The 426 Hemi, often referred to as the “elephant,” became well-known quickly for its use in NASCAR and a few special production vehicle applications. The trademarked name was not officially recognized from a commerce standpoint until February of 1966, 2 years after virtually everyone knew something about it.
However, while most people immediately recognize the term “426 Hemi”, it was not the first Hemi engine. The Chrysler FirePower (not yet coined as a Hemi) 331 V8 was the first to find itself between the fenders of a few 1951 model year vehicles. And there were others … which gets us here.
Each Hemi engine group uses a different exhaust port and bolt spacing. Therefore, Sanderson Headers for the Hemi engines vary slightly to include specific port and bolt layout flanges and varying primary tube bend radiuses to accommodate different exhaust port exit angles. Here are the four Hemi engine groups for which Sanderson builds headers. You will see in the list below that the Dodge and Desoto Hemi engines include a dimension. This is the easiest way to determine the difference between those two engine groups. Please refer to the graphics below the list to explain this dimension.
NOTE: Sanderson does not offer header sets for late model 5.7L, 6.1L, 6.2L, and 6.4L engines.
- Chrysler 426 Hemi
- Chrysler/Imperial FirePower 331-392 (331, 354, 392)
- Dodge 241-325Â (14-3/8″)Â (241, 270, 315, 325)
- DeSoto 276-345 (14-3/4″) (276, 291, 330, 345)
This first graphic shows the 14-3/8″ spacing for Dodge Hemi engines.

This second graphic shows the 14-3/4″ dimension of the DeSoto Hemi engines.

If you have any questions regarding the proper engine group or flange selection, please contact us by phone or through our Helpdesk.
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