Hyperactive Mopar

Hyperactive Mopar

Hyperactive Mopar


The new Mopar® Challenger Drag Pak isn't the first "Pak" car by Chrysler. The first one emerged 50 years ago. It was the "Hyper-Pak" package for the Dodge and Plymouth brand's new 6-cylinder compact cars. Hyper-Pak was developed to compete in a new NASCAR racing series.

Plymouth and Dodge Slant Sixes

The production Hyper-Pak intake manifold. Even the stock Plymouth and Dodge Slant Sixes had long-runner manifolds, but not as long as this one— and with much smaller carburetors.

NASCAR president Bill France had what he thought was a great idea back in 1959 for the upcoming 1960 stock-car season; a race series for compact cars. It would include the new Detroit small cars—the Dodge Lancer and Plymouth Valiant, the Chevrolet Corvair and Ford Falcon. Against the increasingly-popular imports, such as Volvo, these Detroit cars were introduced to fight off the European invasion led by the increasingly popular Volkswagen Beetle. The new Detroit small cars were expected to put up big sales numbers and push the pesky foreign cars off America's shores.

Tom Hoover was the engineer in charge of the Hyper-Pak development program. It was his first high-performance program at Chrysler.

The compact series was scheduled to kick off on January 31, 1960, at the new Daytona Speedway, with a race on the road course and another race on the high-banked Tri-Oval on the same day.

Chrysler product planning manager Jack Charipar liked the idea, and his race group, led by Bob Cahill, Manager of Vehicle Performance Planning, came up with a package of changes to the new Valiant and Lancer chassis and engine for the race track. Cahill had a lot of experience in motorsports. He ran Chrysler's programs for the Pure Oil Performance Trials and the Mobil Economy Run. Later he would concentrate on drag racing, dreaming up the famous Max Wedge and HEMI® Package Cars Chrysler built from 1962 through 1968.

Cahill's Hyper-Pak product plan included a high-performance version of the standard 170-cu-in Slant Six engine1 and a beefed-up 3-speed manual transmission with a special clutch and pressure plate. The program also included a stiffened body structure. "We doubled up on the welding spots," said Cahill. He also specified racing brake linings, a harder compound that took the heat better (but warmed up slowly). There were other changes to the chassis for better handling.

Tom Hoover was given the job of developing the Slant Six for the new class. He was an engineer in the engine development lab at Chrysler. He was also a hot rodder—a member of the Ramchargers, the Chrysler engineering car club that was already on its way to fame with the wild High and Mighty NHRA record holder.

Hyper-Pak was his first racing development project at Chrysler.

"Jack Charipar had great vision," said Hoover. "He stirred up interest in Bill France's compact class." Charipar pushed the plan through the approval process. Plymouth VP Bob Anderson favored high-performance as a marketing tool, and he supported Hyper-Pak.

Ronney Householder, Chrysler Corporation’s stock car racing manager, was also on the team. "Bob Anderson brought Householder aboard Chrysler," said Hoover. Householder was a legendary racer of Midget and Indy cars before and after World War II.

The engine development was straightforward. Hoover increased power the usual ways: Get more air and fuel into the engine, compress it harder, fire it sooner and let it out easier—all the while spinning the whole assembly faster to get the horsepower numbers up. That meant a hot cam and a bigger carburetor feeding the increased air-fuel mixture volume through bigger valves and ports. Opening the valves more and holding them open longer lets more air in. More air equals more horsepower. The most visible feature of the engine was the long-branch intake manifold, topped by a Carter AFB 4-barrel carburetor. The manifold reflected Chrysler Corporation's (and Hoover's) thinking at the time, as embodied by the Chrysler 300's long ram manifolds that overhung the valve covers on the 413 V-8; not to mention the long pipes up to the carburetors on the High and Mighty.

"Bob Cahill took a car or two and did a representative endurance test," said Hoover. "It was quite a thrilling job," Cahill said in his usual understatement. "I drove the cars home and back. It was winter and we had no heat to the carburetor, so the engine would hardly run until it warmed up. And we had metallic brake linings, so the brakes didn't work the first few times until they got hot." Thrilling, indeed. Householder contributed to the endurance testing by driving one of the cars to Daytona for the races—with his family!

Hoover said, "The only real issue out of our testing was the gear that drove the oil pump. To fix that, we specified a 'super finish' on the gear—not a heat treat or hardening, but just finishing the gear better than stock."

Bob Cahill

Bob Cahill, Manager of Vehicle Performance Planning, wrote the specifications for the Hyper-Pak and saw the program through. 1998 photo courtesy of Bob Cahill

Jack Charipar

Jack Charipar headed Chrysler product planning. A high-performance enthusiast, he pushed the Hyper-Pak program through to approval for the Daytona compact-car race.

Hyper-Pak Slant Six engine

The 170-cu-inch Plymouth Valiant Hyper-Pak Slant Six engine. There was a Dodge Lancer version, too. A production version was made available to dealers in early December 1959. It had a 10.5:1 compression ratio, 148 hp and 153 lb-ft of torque (The stock 170 cid engine was rated at 101 hp). Hyper-Pak was released to qualify the engine for the NASCAR compact-car race at Daytona scheduled for January 31, 1960.

Chrysler built seven cars for Daytona. Drivers would include NASCAR regulars Lee and Richard Petty, Larry Frank, Jack Smith and Marvin Panch along with road racers Jeff Stevens and SCCA National Champion Paul O'Shea. Lee Petty would drive the road course and his son Richard would handle the speedway.

Opposing the Valiants were strong driving teams from Chevrolet, Ford and Volvo. International road racing star Ricardo Rodriguez was in a Chevy Corvair along with NASCAR standout Fireball Roberts. Road racer Ed Hugus was in another Corvair. NASCAR's Curtis Turner and Joe Weatherly drove Ford Falcons. At least eight Volvos were in the race, driven by such road racing luminaries as Pedro Rodriguez (Ricardo's brother), Denise McCluggage and SCCA champion Chuck Dietrich. Future Chrysler partners Nash and Simca were also represented—with NASCAR star Speedy Thompson in the French Simca.

The Valiants proceeded to dominate every phase of the road race, which was televised live by CBS. Panch won, followed by the other six Valiants. The competition was nowhere to be seen, with Joe Weatherly (Falcon), Ricardo Rodriguez (Corvair) and Jim Reed (Corvair) rounding out the top 10.

Panch, according to reports, had a trick up his sleeve for the next race, which was on the high-banked speedway. He had his crew change the rear gears to a ratio more suited for top speed. The work made him late for the start (Cahill kiddingly said he was "on the podium kissing the race queen"). By the time he got into his Valiant and headed out of the pits, the field was a half lap ahead. Nevertheless he won the race, aided by a big crash on the fourth lap that let him catch up. Most of his competition had no experience with speedway racing and had never run in a draft. At the re-start he went right to the front. The rest of the Hyper-Paks followed, easily outdistancing the Falcons and Corvairs. The Valiants took the top three spots, followed by Joe Weatherly and Curtis Turner in Falcons. The other four Valiants, including Richard Petty, were eliminated in the lap-four crash.

"I'll never forget the sound of that engine," said Cahill, who was at the race. "It sounded like a Maserati." Cahill was a road-racing enthusiast and would have heard the beautiful exhaust notes of the inline Italian 6-cylinder engine. The tones were famously described at the time as the sound of "ripping canvas."

Ronney Householder

Ronney Householder was in charge of Chrysler’s stock-car racing programs. He drove his family down to Florida in one of the Hyper-Pak racing cars.

Exhaust Manifolds

Exhaust Manifolds: On bottom is the manifold for the front three cylinders. The other manifold evacuated the rear three cylinders.

Pat Bradley

A fabricated steel prototype Hyper-Pak intake manifold with a Carter AFB four-barrel carburetor. The manifold was a product of all Chrysler had learned up to that point about ram tuning. Master craftsman Pat Bradley made it. Hoover said, “He had a great sense of three dimensions and could take a drawing for a casting and fabricate it beautifully in sheet metal.”

The ultimate result of the Hyper-Pak's total destruction of the competition at Daytona was a boring race. CBS, Ford and Chevrolet weren't going to support the series, and so Bill France's great idea collapsed.

Cahill ended up buying one of the Valiant Hyper-Pak cars. "It was the blue one, driven by Paul O'Shea. I pulled out the Hyper-Pak engine and put in a 225-cu-in version of the Slant Six." He used the car as family transportation. He doesn't remember what happened to the car after that. It must have been a great ride.

The Slant Six was designed by Willem E. "Bill" Weertman, the engine designer who would later create the 426 HEMI.

Courtesy of Mopar Magazine

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