MerCruiser & Corvette pair for performance

Maybe the best way to prove technical innovation and manufacturing prowess is to be selected to power an American icon. Such was the case in 1988 when Mercury Marine was chosen to manufacture the LT-5 engine for the 1990 ZR-1 Corvette.

Designed by Lotus Engineering for General Motors, the LT-5 was an all-aluminum 5.7 liter small-block V8 featuring radical 32-valve dual overhead cam heads; it generated 375hp and was hand-built by Mercury’s MerCruiser division in Stillwater, Okla. For the 1993 model year, horsepower was bumped to 405 with cam timing and engine porting changes. Further proof of MerCruiser’s production proficiency occurred when the LT-5 was awarded the automaker’s most demanding quality certification — GP3 Level 1 — the first GM engine ever to earn it.

The LT-5 became the most celebrated Corvette engine of all time, accumulating records along the way. In 1991, a slightly modified ZR-1, with a “bone stock” LT-5, broke three world endurance records at the Firestone test track in Fort Stockton, Texas. A team of drivers headed by Tommy Morrison broke the 24-hour endurance mark set in 1940 by almost 15 miles per hour, traveling 4,221.26 miles at an average speed of 175.885 mph. Two years later, a MerCruiser-branded ZR-1 took the checkered flag in the 24-hour World Challenge race in Mosport, Canada, with another ZR-1 finishing second.

As production of the LT-5 wound down in 1994, ZR-1 owners converged on the Sooner State to pay tribute to those who built the legendary power plant. Seventy owners towed, shipped and drove their ‘Vettes to Oklahoma to participate in a two-day event know as “Thunder in Stillwater.” Festivities began with the visitors escorting the homecoming court and cheerleaders to the local football stadium for the big game. Plant tours followed, during which the owners shook hands with the men and women of the LT-5 production line. The cars were then driven to Oklahoma State University and arranged on the football field to spell out LT-5.

It was a bittersweet moment for all, but one they will never forget.

The Wette Vette

Among Mercury Marine’s best known forays into automotive engine building occurred when it was selected to produce the all-aluminum, LT-5 V8 engine for the 1990 Corvette ZR-1; perhaps the first in a long line of automotive- themed boat/car pairings.

Auto enthusiast Fred Kiekhaefer — at that time Mercury’s vice president of marketing — thought the project with General Motors could provide some favorable publicity. A marinized version of the engine was rigged into a 24-foot Baja powerboat painted to match the car, towed on a trailer with Corvette wheels and nicknamed the “Wette Vette.”

The pair — boat and care — appeared at boat and auto shows around the country and was photographed running neck-and-neck, providing publicity shots that were published in automotive and marine enthusiast magazines around the world. The promotion was so successful, GM kept it on the road for an entire year, wowing boaters and car buffs alike.