Here's a nice description of the Hyper Pack's performance in the 1960 NASCAR comact car class courtesy of allpar.com.
In 1960, in building #135 of the
Chrysler complex in Highland Park, Michigan, the very first high-performance
slant six was born. The 170 cubic inch slant six was originally designed in 1958 to replace the flat-head six, which was big and bulky, and underpowered for the new Valiant compact
car line for model-year 1960.
With the release of the compact 1960 Plymouth Valiant, NASCAR sanctioned a special race for the new six-cylinder compact car class, which would involve all three major automakers.
Located in building 135 was a special group of Chrysler racing engineers that worked in Dyno Cell 13. With NASCAR putting out word of the special race, the engineers went to work on the 170 cid slant six. This special group would be responsible for taking an ordinary 170 cubic inch six and making it put out extraordinary horsepower, that would earn these Chrysler racing engineers the title of most powerful and feared in-line six cylinder ever built in America.
With these special group of engineers, the 170 slant six would be transformed from economy to high performance and the question of the slant six
durability and performance would be put to the test in front of millions of TV viewers.
The 1960 Plymouth Valiant was only available in a
4 door model; this was given a standard block with a set of special domed pistons for a higher compression ratio. The dome height was .250” above the block and the dome volume was 13.7 cc. The camshaft was a racer brown ST-21 which has a lift of .520, duration of 286°, and a centerline of .108; that was the race version that was used in the Daytona race. The public version of the camshaft was a Direct Connection camshaft with specs of 276° duration with a .430 lift (part 2205620). The next step was valve springs (1944554) and a special set of pushrods (2129619). [Originally we had listed STX-21 which has a lift of .560 and duration of 306°. Thanks, Jim at RB Cams.]
With the intake system, Chrysler racing engineers specifically designed the long
ram intake manifold to give more power around 4-4,500 rpm to help with coming out of the turns. The carb was hung out 21 inches from the cylinder head to force the fuel to give a ram effect for even more power; the carb was a special four-barrel Carter AFB model 3083, which carried part number 2129881.
A set of special cast iron manifolds called the Hyper-Pak header split the manifolds; the front three standard manifold carried P/N 2129899 and the rear manifold carried P/N 2129900. These dumped into a single 2-1/2” o.d. outlet pipe followed by a bigger muffler from an Imperial. The exhaust and muffler carried P/N 2298350. The special air cleaner assembly carried P/N 2129992 with a special air cleaner gasket (P/N 1821170).
A high performance manual 3-speed was used behind the race version Valiant with a special clutch driving disc that carried P/N 2201219, with a clutch cover and pressure plate with P/N 2201223.
The name Hyper-Pak was given while the engineers were doing the dyno runs with their new high performance 170 cu. inch six cylinder; once it fired up the motor would shake and lope badly and some of the engineers commented, “that thing is so hyper!” The rest is history.
With the slant six introduced in 1960 in two versions, a 101 hp, 170 cu.in and a 145hp, 225 cu. in. version, the slant six built its reputation for performance and reliability. The 148hp, 170 cu. in Hyper-Pak introduced in the 1960 Valiant was the next step and the one that was to prove the new engine worthy of any performance challenge.
Seven slant six valiants entered the new NASCAR race; when the race ended, not only had all seven Hyper-Paks finished, proving their reliability and durability, but they won the first seven places!
This type of performance speaks for itself.
In a first, CBS television had aired the compact sedan races as well as the qualifying for the Daytona
500 race in a live TV special for their “sports spectacular;” it was estimated that 17 million people were watching. The compact sedan race quickly turned into a dull affair as lap after lap Lee Petty managed to turn away all challenges. It was made even duller by the fact that besides his Valiant, the next 7 positions were also hyper-pak valiants.
The finishing order was Valiant 1,2,3,4,5,6,7 ! Did Chrysler use that for advertising fodder? Nope. Go figure! NASCAR agreed with CBS on the dull part of the race, and quickly cancelled any other plans for a compact
sedan race.
Not the first time a sanctioning body has changed the rules, because Chrysler showed up ready to race!
