For a hot rodder or racer, a rat engine is a big-block Chevrolet V-8. Powerful and beautifully designed, how did this respected engine get the nickname “rat”?
From James Cagney’s famous phrase “… that treacherous dirty rat” to the much-maligned rats of the 1950s, calling someone or something a rat is the ultimate insult. When something is old, used and falling apart, it is “threadbare.”
So it is somewhat surprising that the great Chevy has earned the nickname of rat.
In the early 1960s, long before the introduction of the first rat engine, a showdown between David and Goliath was taking place on the nation’s airfields. The Chrysler Hemi had become the dominant force in the Top Fuel and Top Gas categories, gradually replacing the Cadillac, Lincoln and Oldsmobile engines that previously controlled these categories.
While the Chrysler Hemi produced a great deal of power, it was also physically larger and heavier than other V-8s. The massive engine quickly earned the nickname Elephant engine due to its size. An elephant engine with a GMC supercharger looked huge when installed on a typical tube frame dragster chassis.
Although large elephants became the de facto standard in Top Fuel, there was another engine that could hold up against the Hemi. Many teams took a different approach, choosing the legendary small-block Chevy to power their dragsters. Most of the time, they didn’t bother with a supercharger, preferring a simple set of injectors.
On paper it was uneven competition. The busted hemi was far more powerful than the tiny Chevy, and the Chevy didn’t seem to be praying against the Chrysler in a quarter-mile race.
However, the tire technology of the time was in favor of Chevy rails.
While the big elephant engines developed a great deal of horsepower, the tires of the time weren’t up to the task of delivering that power to the track. Much of that power went up in smoke, as Chrysler’s big rails burned the tires nearly the entire length of the drag tip.
Small Chevies could burn their tires too, but their lower horsepower allowed the tires to snag and gain traction while the large hemisphere kept turning its wheels. The combination of less wheel spin, lighter overall weight, and higher RPM allowed small Chevy-powered cars to give elephant-powered cars a chance.
While hemi teams weren’t really scared of little Chevy dragsters, the little blocks tended to make them more than a little nervous. There was no shame to lose with a busted hemomachine, but it was really embarrassing to lose with an injected Chevy.
Someone recalled the fable that the only creatures elephants fear are mice, and began to refer to little Chevy as the mouse engine. Thus, elephant and mouse engines competed for the honors of runway racing across the country.
The role of the mouse engine as an elephant killer did not last long. Tire and clutch technology continued to improve, and the big elephants were finally able to deliver more power to the track. By the early 1960s, the mouse engine could no longer affect the big Chryslers in the Top Eliminator ranks. The small-block Chevy was still very popular in the modified, gasoline coupe, and modified classes. Although it rarely raced against large elephant engines anymore, the engine was still known as the mouse engine.
During that period, Chevrolet and General Motors followed a strict no-racing policy. It is well known that some GMs overlooked the official position by supplying parts and technical assistance to brokers without the knowledge of management.
Legend has it that in the early 1960s, certain Chevy drivers showed up at various race tracks with a strange new engine under the hood. It wasn’t a mouse engine, and it wasn’t the great 409 V-8 that the Beach Boys immortalized in song. It was a brand new, mysterious Chevy V-8.
The mystery was short-lived, as Chevrolet announced a new big-block V8 in 1965. First available as a 396-cubic-inch version, the engine eventually evolved to displacements of 402, 427, 454 CI. GM even offered a monstrous 572 CI version of the engine.
After the engine was introduced, many people continued to refer to it as the mystery engine. When the valve caps were removed, the hot rodders started calling it a V8 porcupine, because unlike the mouse engine that had the valve stems lined up in a neat row, the new engine’s valves were tilted at various angles.
Other racers noted that while the engine was not a true hemispherical design, it was not exactly a wedge head either. Thus, the engine gained another name: the semi-hemi.
Look at photos of Chevrolet race cars of the time and you will find many examples of cars with the terms Mystery Engine or Semi Hemi painted on the hood.
For most rodders and racers, however, there was only one legitimate nickname for the new engine. If the little Chevy V-8 were a mouse engine, its bigger, more powerful, and fiercer brother could only be a RAT engine.
The name has stuck. Today, only old school fans and nostalgia buffs still use the terms mouse and elephant motor. The name rat engine, however, is still widely used to describe the big-block Chevy V8. Far from being a derogatory term, the term rat engine is popular with Chevy fans and is used as a title of respect by those who build and compete with other brands.
And that’s how the Chevy V-8 became known as a rat engine.
