Pontiac straight-8 engine

The straight-8 was dubbed the Silver-Streak[2] at Pontiac Division. Powered by the "eight", optional in lower-end models, a Pontiac was promoted as a likable automobile, with enough power under the hood to get the job done in affordable luxury.

However, by the early 1950s, powerful overhead valve V8s from sister GM Divisions Cadillac, Buick and Oldsmobile, as well as new overhead valve V8s from Ford Motor Company and Chrysler Corporation, made the flathead "Silver Streak" all but obsolete. It was a quiet, smooth running, cheap to produce engine that served the needs of the 1930s and '40s Pontiac buyers adequately for power. By 1953 the 287-cubic-inch (4.7 L) Strato Streak V8 was ready to go, with Pontiac chassis and steering already adapted for it, but it was held back by the protesting Buick and Olds divisions. It was a truly modern, durable but affordable design perfectly matched to Pontiac's target market. A few years later (fall of 1956), under the guidance of Bunkie Knudsen Pontiac was determined to change its image into a performance car to boost sales, this led Knudsen to look for further talent, including Pete Estes as chief engineer (taken from Olds division) and John DeLorean as director of advanced engineering, a former Packard and Chrysler engineer. Pontiac became known as a performance division based upon the durable, well performing V8s that came later, all of them based upon the original 287 of 1955.

Compression on the "eight" started at 5.7:1 initially,[3] and was increased to 6.2:1 in 1934.[1] In 1940 it was increased again to 6.5:1. From 1952 to 1954 two compression ratios were specified, 6.8:1 with synchromesh (manual) transmission, and 7.7:1 with Hydramatic automatic transmission.[4] The engine had a remarkably low idle speed of 450 rpm with standard transmission and 375 rpm (while in drive) for the automatic;[5] a modern engine is usually tuned to a minimum 600-700 rpm. The electrical system was a 6-volt primary with a negative ground, and a conventional mechanical ignition, with the firing order 1-6-2-5-8-3-7-4. The Pontiac engines employed a full pressure oiling system and full bearing inserts, unlike its Chevrolet cousin.

Below are specifications as per the model year and displacement, with output shown as horsepower (kilowatts).

At the General Motors Motorama for 1954, Pontiac debuted its all new Bonneville Special, a concept car envisioned by head designer Harley J. Earl. The concept was equipped with the "Special"-8, a high output 268-cubic-inch (4.4 L) engine that was painted bright red and detailed in chrome. This was a unique configuration for the "eight", installed in the only two Specials ever made. Similar in appearance only, this was a high compression variant, modified with a high-lift cam and fitted with four Carter YH side-draft one-barrel carburetors, the same used in the 1953 Corvette, under open-mesh breathers. Total output was the highest ever for the "eight", rated at 230 bhp (172 kW), though some estimated it at over 300 bhp (224 kW).[14] Like the Special, only two were ever made.

Note: Pontiac’s new V8 was being considered for use in the Special but was instead held back by GM marketing. They directed that the straight-eight be used to keep the V8 a secret from consumers for one more year until its debut the following year.[15]

• Pontiac Trophy 4 engine
• Pontiac straight-6 engine
• Pontiac V8 engine
• List of GM engines