engine used in the Cold War model Chrysler Air Raid Siren is virtually
the same 331 Hemi FirePower engine used in 1951, 1952 and 1953 Chrysler
cars like the Saratoga, New Yorker and Imperial.
Introduced in 1951 it was Chrysler's first V-8 engine. It
represented an impressive improvement in engine design that produced 180
horsepower and a then high compression ratio of 7.5. A paper
presented at the 1951 SAE National Passenger Car, Body, and Materials
Meeting in Detroit touted that, "The performance, efficiency, durability and general
operating characteristics of this new engine are outstanding, and
further improvements are assured by continued development and use of
fuels of higher quality."
This early Chrysler Hemi is easily identified by the engine block
extension at the rear that housed the fluid coupling. This is true
of both the early vehicle and industrial models.
Hemis can be also
be easily identified by the numbers stamped on top of the block in front
of the valley cover. Early vehicle 331 engines started with C51-8,
C52-8, and C53-8. The two digits represent the year of
manufacture. Industrial engines used on Chrysler Sirens start with
IND-20. The engine number on the BigRed™
Siren is "IND-20-4068" [
themselves are different on pre-1955 Hemi engines. Starting in
1955 the heads feature a water outlet on the front end. The early
1951-53 heads also had round exhaust ports that would be larger and oval
in later years.
Hemis also have a threaded extension on the front end of the camshaft
where a nut is used to retain the cam gear.
Sirens were being retired they became a popular source of hot rod
According to Hot Heads, a leading supplier of
parts for early Hemis, the 331 can easily attain one horsepower per
cubic inch and considerably higher torque than the factory 312
foot-pounds at 2000 RPM. Boring and blowing this engine can
produce respectable performance statistics for the hot rod enthusiast.
In the 1960's drag
racers, like fellow Chrysler Siren owner "Big Daddy" Don Garlits,
using the large V8 Hemi engines that evolved from the 331.
331 Engine Photographs ]
More Chrysler Siren Engine Information ]
Chrysler Industrial Engine IND-56 Operating Manual ]
Service Reference Books ]
Siren Specifications ]