Pontiac Straight-6 engine
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Like most American automobile manufacturers, Pontiac relied on the straight-6 design for their circa-World War II automobiles.
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[edit] "Split Head" Six
[edit] 186
In the 1920s Oakland Motor Car engineers designed an all new engine for their "companion" make, the Pontiac, which was introduced in 1926. It was a side-valve design with a one piece cast iron block with three main bearings. An unusual feature was that it had two separate cylinder heads that each covered three cylinders. The Ignition distributor was mounted on top of the block in the gap between the heads. This engine displaced 186.5 Cu.In.(3.1 L) and was rated at 40 BHP (29.4 Kw) @ 2400 RPM when it was introduced. The compression ratio was 4.8-1.[1]
[edit] 200
In 1929 the " split head" Pontiac six was increased in displacement to 200.0 Cu.In. (3.3 L)., The horsepower rating increased to 60 BHP (44.2 Kw) @ 3000 RPM. Compression was increased slightly to 4.9-1.[1] The "split-head" six was discontinued by Pontiac at the end of the 1932 model year. Pontiac offered only eight cylinder engines during 1933 and 1934.
[edit] Flathead Six
[edit] 208
In 1935, Pontiac re-introduced their six cylinder engine, as a 208 in³ (3.4 L) straight-6. The 208 was produced in 1935 and 1936. It was a side-valve design with a timing chain, as was popular at the time. This engine featured a conventional one piece cylinder head, and the distributor was moved to the side of the block. The number of main bearings was increased to four. Like the Pontiac Straight-8 engine it also featured full-pressure oiling, and, insert type precision main and rod bearings. These two latter features greatly increased longevity and durability especially under high speed conditions.
[edit] 223 Pontiac/GMC
Just as was done with their later V8s, Pontiac shared their mainstream straight-6 engine with GMC for truck use. It was also a side-valve engine, and used a timing chain. The 223 in³ (3.7 L) straight-6 was used in Pontiac automobiles (1937-40) and GMC trucks (1938 only).
[edit] 239
The 239 in³ (3.9 L) straight-6 was similar in design to previous sixes. It was used from 1941 through 1954 only in Pontiac automobiles.
[edit] Specifications
| Year | Model name (number) | Disp. | Output BHP (kW) @ RPM | Torque lb.ft. (Nm) @ RPM | Compression | Carburetor series (bbl) | |
| 1935 | Master&DeLuxe 6 (6-35) | 208.0 | 80 (58.88) @3600 | 150(203.40) @ 1600 | 6.2-1 | Carter W-1 (1) | [2] |
| 1936 | Master&DeLuxe 6 (6-36) | 208.0 | 80 (58.88 @ 3600 | 150 (203.40) @ 1600 | 6.2-1 | Carter W-1 (1) | [2] |
| 1937 | Six (6-37) | 222.7 | 85 (62.56) @ 3520 | 161 (218.32) @ 1600 | 6.2-1 | Carter W-1 (1) | [2] |
| 1938 | Six (6-38) | 222.7 | 85 (62.56) @ 3520 | 161 (218.32) @ 1600 | 6.2-1 | Carter W-1 (1) | [2] |
| 1939 | Quality&DeLuxe 6 (39-25) & (39-26) | 222.7 | 85 (62.56) @ 3520 | 161 (218.32) @ 1600 | 6.2-1 | Carter WA-1 (1) | [2] |
| 1940 | Special&DeLuxe 6 (40-25) & (40-26) | 222.7 | 87 (64.03) @ 3520 | 164 (222.38) @ 1400 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1941 | Custom,DeLuxe & Streamliner Torpedo 6 (41-24),(41-25),& (41-26) | 239.2 | 90 (73.59) @ 3200 | 175(237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1942 | Torpedo & Streamliner Torpedo 6 (42-25) & (42-26) | 239.2 | 90 (73.59) @ 3200 | 175 (237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1946 | Torpedo & Streamliner 6 (46-25) & (46-26) | 239.2 | 93 (68.45) @ 3400 | 175 (237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1947 | Torpedo & Streamliner 6 (47-25) & (47-26) | 239.2 | 93 (68.45) @ 3400 | 175 (237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1948 | Torpedo & Streamliner 6 (48-25) & (48-26) | 239.2 | 93 (68.45) @ 3400 | 178 (241.37) @ 1400 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1949 | Silver Streak 6 (49-25) | 239.2 | 93 (68.45) @ 3400 | 178 (241.37) @ 1400 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1950 | Silver Streak 6 (50-25) | 239.2 | 90 (66.24) @ 3400 | 178 (241.37) @ 1200 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1951 | Silver Streak 6 (51-25) | 239.2 | 96 (70.65) @ 3400 | 191 (259.00) @ 1200 | 6.5-1 | Carter WA-1 (1) | [2] |
| 1952 | Silver Streak 6 (52-25) with manual trans. | 239.2 | 100(73.59)@3400 | 189(256.28)@1400 | 6.8-1 | Carter WA-1 (1) | [2] |
| 1952 | Silver Streak 6 (52-25) with automatic trans. | 239.2 | 102(75.07)@3400 | 189 (256.28)@1400 | 7.7-1 | Carter WA-1 (1) | [2] |
| 1953 | Chieftan 6 (53-25) with manual trans. | 239.2 | 115(84.63)@3800 | 193(261.71)@2000 | 7.0-1 | Carter WCD (2) | [2] |
| 1953 | Chieftan 6 (53-25) with automatic trans. | 239.2 | 118 (86.84@3800 | 193(261.71)@2000 | 7.7-1 | Carter WCD (2) | [2] |
| 1954 | Chieftan 6 (54-25) with manual trans. | 239.2 | 115(84.63@3800 | 193(261.71)@2000 | 7.0-1 | Carter WCD(2) | [3] |
| 1954 | Chieftan 6 (54-25) with automatic trans. | 239.2 | 118(86.84)@3800 | 193(261.71)@2000 | 7.7-1 | Carter WCD(2) | [3] |
[edit] Overhead Valve
In the mid-1960s, Pontiac revived their straight-6 for a short time. Although it was of a different displacement, this Pontiac engine was based on Chevrolet's Generation 3 straight-6.
[edit] Pushrod 215
The 215 in³ (3.5 L) straight-6 was produced in 1964 and 1965. It is sometimes confused with the 215 aluminum V8 used in the two years prior. It was an OHV/pushrod engine design, quite different from the previous Pontiac straight-6 engines.
[edit] Overhead Cam
The OHC straight-6 design was adopted by Pontiac in the 1966 model year. This was a redesigned Chevrolet Straight-6 available in the Pontiac Firebird and the Pontiac Tempest. This engine was produced from 1966 through 1969. It was the first American high performance six cylinder engine since the demise of the Hudson Hornet and the only American high performance six of the 1960s.
The OHC six engine was available initially in 1966 and 1967 as a base motor for the Tempest and Le Mans cars. It had 165 bhp (123 kW) and a displacement of 230 in³ (3.8 L). With the Sprint Option it produced 207 bhp with 10.5:1 Compression and a Quadrajet carburetor.
In 1968 and 1969 the engine displacement was enlarged to 250 in³ (4.1 L) producing 175 bhp in standard form and 215 bhp (160 kW) in the power version.
The Pontiac 3.8 was a SOHC engine based on the standard 230 (3.8L) Chevrolet I6 block, putting it in the avant garde of Detroit engineering. The camshaft was driven by a quiet belt instead of the usual chain, making it state of the art for the time. This engine was used on the 1967 through 1970 Pontiac Firebird while saving quite a bit of weight in the front of the car, compared to the V8 models.
However, new car buyers preferred V8 engines in that period. So the OHC engine was stopped in 1970. Instead, Pontiac offered standard OHV sixes produced by Chevrolet.
Like other Pontiac engines of the era, it was not available in Canada; Canadian Pontiacs came with the Chevrolet OHV six instead.
