In the early years of NASCAR, Hudson dominated the field with a lowly flathead six. Here’s our take on why such an unlikely engine worked so well.

Even the most casual NASCAR fan knows the story of the fabulous Hudson Hornets that dominated the early years of the sport. While there’s no question that the Hornet was a total package, it couldn’t have been a consistent winner without a competitive engine. And for fans of the modern era, that poses a question: How could a seemingly backward L-head six stand its own against the new and powerful overhead-valve V8s coming from Detroit, especially Oldsmobile?

First: While the L-head Hornet wasn’t quite state of the art, it was still a high-quality engine. Though Hudson, one of the smaller automakers, lacked the technical resources of, say, General Motors or Chrysler, the company had a proud engineering tradition with a culture of “when in doubt, build it stout,” with high-chromium iron alloy castings and other robust features. In the rugged environment of NASCAR’s pioneer days, overengineering was a plus.

Next, the Hornet was unusually big for an American L-head six. At 308 cubic inches, it was even a tiny bit larger in displacement than the 303 CID Olds Rocket V8—its chief NASCAR rival. The Hornet was part of an engine series informally known as the Wide Block family, also produced in more conventional 232 and 262 cubic-inch versions. With a 3.8125-in bore and a mighty 4.500-in stroke, the 308 Hornet (aka 7A) was the biggest of the lot. And in racing, they say there’s no replacement for displacement. In normal tune with a single two-barrel carburetor for its 1951 introduction, the Hornet produced an easy 145 hp at 4,000 rpm and 257 lb-ft of torque at just 1,600 rpm. The 1951 Olds Rocket was rated at 135 hp, so even in base form the Hornet was in the game.

Where Hudson really stepped up was with the Twin-H package, a dual-carburetor system originally offered as a dealer kit in 1951, then as a regular production option in 1952. Here, the standard Carter WGD two-barrel carb was replaced with a pair of WA-1 single-barrels (and two giant air cleaners). This not only increased air and fuel flow, it significantly improved fuel/air distribution, a traditional shortcoming of inline sixes. Rated output was boosted to 160 hp at 4,000 rpm, though stated torque was unchanged.

By that time, Hudsons were tearing up the dirt tracks down South, and when the company learned of the Hornet’s unanticipated success—prompted by a vist to Detroit by leading Hudson racer Marshall Teague—executives saw an easy and inexpensive PR win. Working through its racing representative Vince Piggins (who later took a similar role at Chevrolet), Hudson threw in its support with heavy-duty axles, chassis and driveline parts, advertising dollars, and most importantly for our story, the Hornet 7X engine and components, sold straight over the counter by Hudson dealers.

The 7X is the stuff of NASCAR myth and legend, some of it sketchy. But it is documented that there were multiple camshafts developed, the raciest being the “040” grind with .390-in valve lift and 268 degrees of duration. It didn’t idle like a stocker, but it bore a factory part number. Valve diameters were increased to 2.00-in intake and 1.687-in exhaust, a split exhaust manifold was engineered, and the cylinder block was carefully massaged and blueprinted, substituting larger 1/2-inch head bolts.

Cylinder heads from the 232 and 262 engines supported compression ratios of up to 9.2:1—remarkable for an L-head combustion chamber. Compression ratio is a major factor in engine efficiency and output, and here the Hudson engineers managed to compete with their overhead-valve rivals. And that, for us, is one more key to the Hornet’s success. Although no official output figure was reported (wisely), estimates ranged from 220 to 270 hp.

While there was some pushback from series officials at times, all these pieces were factory-supplied and thus NASCAR legal for the most part. “Strictly stock,” as the series was billed at the time. But in reality, the Hornet 7X was in effect a race-prepped engine, with builders including Smokey Yunick applying their special touches. Hudson won 80 races between 1951 and 1955, including 27 of 34 events in 1952 and three straight season championships. Lessons learned in NASCAR were applied to Hudson’s regular production engines in 1954, marketed as “Instant Action,” and more of the upgrades were used in Hudson’s final Hornet sixes in ’55 and ’56.

Hudson won its last major NASCAR race on February 6, 1955 in a 100-miler at West Palm Beach, Florida. By then, the Hudson brand was fading fast at American Motors, and newer and better V8s were arriving in NASCAR, including Chevrolet. However, Hornet sixes remained competitive in open-wheel modifieds for several more years, and all through the ’60s, Hudsons were ringers in NHRA stock and six-cylinder class drag racing. NASCAR is a very different sport today, but it will always have the unlikey legacy of a dominating L-head six, the Fabulous Hudson Hornet.