Chrysler FirePower engine

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The FirePower was Chrysler's first V8 engine. Introduced in the Fall of 1950 for the 1951 model year, the FirePower had hemispherical combustion chambers, leading some to refer to this engine as the early Hemi or Generation 1 hemi. It was replaced by the Chrysler RB engine in 1959, though a different version of the hemi heads would live again in the RB-based 426" Chrysler Hemi engine in 1964.

Chrysler, Dodge (Red Ram), and DeSoto (FireDome) all built their own versions of this engine (but not Plymouth which stayed with poly-head engines). The Chrysler, Dodge, and DeSoto versions were all independent with almost no parts in common. There was no Plymouth hemi engine until the 1964 426.

Chrysler and Imperial

The Chrysler Fire Power engines were the first Chrysler Corporation Hemis. They have the largest bore center distance (also called bore pitch distance) of any Chrysler engine at 4.5625 in (115.9 mm) (except the B/RB).


There was a 301 cid engine with the polyspherical heads only made in 1955 that went into the Chrysler Windsor to finally replace the old 265 cid flathead inline 6. It was replaced in 56 by the polyspherical headed 331.


All Chrysler FirePower engines were oversquare in that the bore was larger than the stroke — the 331 bore was 3.8125 in (97 mm) and the stroke was 3.625 in (92 mm), for a total of 331 cu in (5.4 liters). Most used a two-barrel carburetor version and produced gross power of 180 hp (134 kW), with the famous exception of the 1955 Chrysler 300 which was equipped with dual Carter WCFB four-barrels carburetors. It was used from 1951 through 1955. This engine competed on equal grounds with the newly introduced Oldsmobile 303 and Cadillac 331 OHV V8 engines of the same era.

The 331 engine was installed in the following vehicles:


The Chrysler 354 was a 354 cu in (5.8 L) version produced in 1956. Bore was 3.9375 in (100 mm) with a 3.625 in (92 mm) stroke. It was used in the 1956 New Yorker, Imperial, and Chrysler 300B. Dodge used a modified version of this engine in the 1957 D-501. The engine was rated at 340hp. An optional 355hp version was available, making it the first American V-8 to be rated at one horsepower per cubic inch.


The 392 cu in (6.4 L) raised-deck version for 1957 and 1958 had a 4.00 in (102 mm) bore and 3.906 in (99 mm) stroke. The actual deck height was 1/2" taller (10.87") than the previous blocks. Because its deck was taller, the heads were cast wider so that earlier manifolds could be used with the new heads on the new, taller, block. It was used in the 1957-1958 New Yorker, 1957 Chrysler 300C, 1958 Chrysler 300D, and 1957-1958 Imperial. The late fifties and early sixties Drag Racers found the 392 to be an auspicious engine for their 'Dragsters', eg. Don Garlits et al.


DeSoto's Hemi engines were called Fire Dome. They have bore center distances smaller than the Chrysler but larger than the Dodge at 4.3125 in (109.5 mm).


In 1952, DeSoto introduced its version of the FirePower. It displaced 276 cu in (4.5 liters) and 160 hp (119 kW). It was a hot seller, with 50,000 vehicles using the engine until it was replaced in 1955. Bore was 3.625 in (92 mm) and stroke 3.344 in (85 mm).


A bump in displacement to 291 cu in (4.8 L) was made for 1955 by increasing the bore to 3.72 in (94 mm).


The DeSoto engine was enlarged for 1956 to 330 cu in (5.4 L). Bore was the same as the 291, but stroke was up to 3.80 in (97 mm) this time with a taller raised-deck block. The DeSoto Adventurer was the premiere name-plate high-performance version (the DeSoto equivalent of the Chrysler 300) using dual Carter WCFB four-barrel carburetors.


Displacement was up again for 1956 and 1957 to 341 cu in (5.6 L). Bore was now 3.78 in (96 mm) with stroke remaining at 3.80 in (97 mm). The DeSoto Adventurer produced 343 hp (256 kW) using dual Carter WCFB four-barrel carburetors, which was greater than one hp per cu in (46 kW/L), just like the Chevrolet Corvette's fuel-injected 283.


The largest DeSoto engine for 1957 was the 345 cu in (5.7 L). Bore and stroke were square at 3.80 in (97 mm). The DeSoto Adventurer used dual Carter WCFB four-barrel carburetors. It was rated at 345hp, again producing one hp per cu in (46 kW/L).


Dodge's Hemi was called the Red Ram, introduced in 1953. They have the smallest bore center distance of any hemi engine at 4.1875 in (106.4 mm).

(NOTE: The DODGE Hemi engines mfd. during 1950's had no harmonic balancer to speak of- they had a front hub of sorts on the crankshaft that slid on, attached to pulleys, and held on by one large bolt/washer- this hub/pulley setup is very light, and has almost zero harmonics absorbing/dampening capability. These engines have been known to break crankshafts for no other apparent reason- it is highly recommended that during any rebuild of the Dodge hemi/poly engines of the 1950s, the crankshaft be carefully MAGNUFLUXED for cracks first, and an aftermarket HARMONIC BALANCER purchased from an aftermarket source-they are available from HOT HEADS. With the addition of a modern balancer, the DODGE engine is as good as any-and actually quite good considering it's smaller/lighter than the Firepower/DeSoto engines, while still being able to reach 325+ CID in stock form. Removing the harmonic balancer from any modern engine, would cause the crankshaft to break in short order. The CHRYSLER and IMPERIAL FIREPOWER and DESOTO FIRE DOME engines do have an OEM balancer.)


The Dodge introduced the 241 cu in (3.9 L) version in 1953. Bore was 3.4375 in (92 mm) and stroke was 3.25 in (83 mm). It produced just 140 hp (104 kW). Plymouth's 241 version for 1955 had polyspherical heads.


The 270 displaced 268 cu in (4.4 L) and was used in the 1955 and 1956 Dodge high-line (premium) vehicles. Bore was 3.625 in (92 mm) and stroke was 3.25 in (83 mm). See also the Plymouth 270 poly-head.


For 1956, Dodge upped the displacement to 315 cu in (5.2 L) with a longer 3.80 in (97 mm) stroke and a taller raised-deck block.


Dodge used a 325 cu in (5.3 L) engine for 1957 until 1958. The engine used a 3.6875 in (94 mm) bore and 3.80 in (97 mm) stroke.