Mopar's Infamous Hemi
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Notable Hemi Vehicles

Prototype and Production Hemi Engines


After World War II, a team from Chrysler looked into using the Hemi head technology for passenger cars. Being most impressed with a Healey engine design, they built a Hemi head for a six cylinder engine in 1947 for testing. The real world testing was a success, and spawned the A182.


1948 Chrysler 330 Hemi prototype engine.


1948-1950 Chrysler 331 Hemi prototype engine. This V8 is shorter and lighter than the A182. It eventually became the Chrysler Firepower.


Chrysler was not doing so great in NASCAR, so in 1962 to 1963, Chrysler worked to create a 426 race Hemi. The basic concept was adding the Hemi heads to the RB 426 engine. It made its debut at the 1964 Daytona 500 (and was very successful).


Ford came out with their 427 SOHC for NASCAR. Chrysler did not want to be in the shadow, so they developed a 1964 426 race Hemi prototype with 4 valves per cylinder and DOHC. But the OHC design was regulated out of NASCAR before they were able to release the design, so the 426 DOHC Hemi never became production.


The lightweight drag-race 426 Hemi developed in 1964. It had a cast-magnesium cross-ram intake with two Holly carbs, aluminum alloy cylinder heads, aluminum water pump, aluminum oil pump, and 12.5:1 pistons. Rumors believe the motor to have over 500 horsepower. The engines were produced by Chrysler Marine division.


404 circle-track race Hemi developed in 1966. Based on the A864 but with a shorter stroke (3.558 in).


1965-1966 426 race Hemi prototype based on the shorter stroke of the A117 but with a larger bore (4.363 in) and larger valves. Both aluminum alloy and iron cylinder heads were tested with, along with a gear-driven cam and a flat crankshaft.


1965 426 street Hemi.


1967-1968 426 Stage II street Hemi.


1968-1970 440 Ball-Stud Hemi big-block prototype. Originally developed as a low-cost competitors for the Chevy big-blocks. Ball studs were used instead of forged rocker arms and Hemi heads were added.

Last Updated: 2003-02-10

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