By Chuck Petersen
Pre-WWII outboard speed records were largely held by wealthy Europeans running low production, hand built race engines that resembled small automotive plants. Many family boaters during the 1930s were not running a 987cc supercharged dual overhead cam Soriano opposed six cylinder rig!!!
This all changed in 1957 with the introduction of the Mercury MK75 60hp tower of power. Chief engineer, Charlie Strang had conducted a secret development program in 1956 ignoring boss, Carl Kiekhaefers orders to focus 100% on the NASCAR auto racing hobby/obsession of Carls at that time.
Jeff Rodengens book Iron Fist, the Lives of Carl Kiekhaefer outlines many such interesting details of this influential mans life. The rapid development of the in-line 6 cylinder was one of many Mercury milestones fostered by a uniquely talented core of executives willing to risk the wrath of Carl to prove their ideas would work and in turn benefit the company.
In January, 1957, Charlie Strang was contacted by Jack Leek and Hugh Entrop of Seattle, WA who felt they could set a new world outboard speed record in excess of 100 mph if allowed access to a Merc. MK75H engine. Like the smaller MK55H, the 6 cylinder brute was essentially a stock powerhead mounted on a Hydro Quick short tower and bullet gear case. Charlie Strang agreed and he modified the stock engine to burn pure alcohol via special carburetors. Two other key players in this effort were boat builder Ted Jones and prop wizard Don Henrich. Think about this fact: A stock MK75 was rated at 60hp at 5500 rpm. Charlie managed to coax 83hp at 7500rpm from the MK75H. Even with these impressive numbers the Americans were running about half the horse power then being produced by the exotic French/Italian Soriano mill.
The key advantages needed to set the record would involve better hp/weight ratio and superior boat and prop design. I raced Hydroplanes in the 1980s and saw marked increase in performance/records during the period with essentially the same power plants run in the 1960s. The difference came from prop and hull design improvements.
On June 7, 1958, Entrop literally flew the Joness designed cab-over hydro through the time traps at an average speed of 107.821 mph. Close inspection of photos taken show a telltale pattern of chop marks in the spray behind Entrops boat. This prop-riding had, until then, only been achieved on inboard hydroplanes like the Slo-Mo-Shun unlimited. This marked the first time the outboard record rested in America in 21 years.
While Carl Kiekhaefer initially tried to shift the focus away from the principles involved and toward the Mercury Corporation, eventually he acknowledged the truly amazing team effort and driving skills of Hugh Entrop. This event would signal the start of continuing wars between Mercury and OMC for horsepower and speed records. It must have been an exciting time to be involved in the industry.