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RistoCompetition is a good thing. Every time we think it's safe to proclaim a new inboard horsepower champion, rumors start flying about some new “hot” engine in the works across the lake.
The most recent trend is toward high-performance specialty engines. Offered in limited numbers, these custom-built V-8s aren't intended for everyday ski-boat duty. Rather, they're highly tuned, balanced and blueprinted engines built for special-order applications like limited-edition boats. We're talking 350-plus horsepower here, out of small-block V-8s. Tuner engines are for the “money is no object, gotta have the quickest, fastest, baddest-sounding boat on the water” buyer. And yes, there does seem to be a solid market for these high-end engines.
Here in the real world, the good news is that there is a trickle-down effect to advances in marine power. What was considered a hot inboard just a few years ago is now a mainstream powerplant. Horsepower and torque numbers continue to rise as competition moves the bar upward. Remember when 215 hp seemed like a lot? For 1997, engines delivering 300-plus hp are common.
Electronic fuel injection, and the computerized controls EFI brings to the party, are the reason why. Once the inboard industry made the commitment to EFI, power improved along with fuel economy and overall drivability. Precise fuel delivery coupled with computerized engine management systems allow engine builders to calibrate performance parameters that weren't available in the days of breaker ignitions and carburetors.
The efficiency of EFI has also opened the door to traditional hot-rodding tricks without sacrifices in drivability. The modern performance inboards are often tweaked with a higher compression ratio, hotter camshaft grind, roller lifters and freer-flowing heads, thanks to generous porting.
With all the competition and development work that is buzzing around the marine-engine industry, it's only natural that the engine companies are working more closely with boatbuilders. The synergy is producing proprietary engine models for individual boat lines – a trend we see growing in the years to come.
Is competition a good thing? Just hammer the throttle open on any one of the tournament inboards in our 1997 roundup and we're sure you'll agree: Marine horsepower wars make for some real excitement – at both ends of the rope. In the following overview, you'll find out what the top inboard marinizers are offering for the high-horsepower arena, along with a host of other models that benefit from the trickle-down effect.
INDMAR
After introducing the mighty Monsoon 320 in 1996, there was a great deal of speculation about what else Indmar might have on the dyno. As you can tell from our October '96 issue, the speculation was well-founded. Indmar, in conjunction with Malibu and Callaway, recently pulled the wraps off one monster small-block inboard, the SuperNatural 383-cid V-8, which powers the limited-edition Malibu Corvette. This 6.3-liter small-block is based on the Gen1+ GM V-8 and sports port fuel injection. It produces a whopping 400 hp and a rope-snapping 415 foot-pounds of torque. It features a 10.5: 1 compression ratio, special-grind marine cam, high-lift roller lifters, Callaway forged aluminum racing pistons in a 0.030 over-bore, and 3.750 stoker rods hung on a 4340-steel crankshaft. The stout 'Vette motor even looks the part, thanks to generous use of steel braided lines and specially milled and anodized aluminum accessories. Sure, you have to buy a $45,000 Malibu Corvette Limited Edition Ski Boat to get the engine, but if you want your engine hand-assembled by Callaway, one of the best engine tuners in the world, it's the only game in town.
The Indmar Monsoon 320 has become the largest-selling premium engine in the Malibu line, so expect to see more of them on the water in '97. The Gen1+ Vortec 350 is tuned with a 9.4:1 compression ratio, multi-port EFI and special calibrations for the three-dimensional ECM optimized to work with Malibu's SV23 hull design. The computer controls air, fuel and spark to the engine by monitoring rpm, throttle position, manifold pressure and coolant temperatures.
Indmar introduced its Tour Edition 5.7L LT-1 EFI small-block back in 1993, and it has become a performance standard in the inboard industry. Based on the GM LT-1 Gen II Corvette block, the Tour Edition LT-1 EFI features LT-1 high-compression (10.25:1) aluminum heads, tuned aluminum intake, roller cam, multi-port EFI and GM's NorthStar distributorless ignition system.
Indmar's Tour Edition 5.7 EFI is also fitted with their three-dimensional computerized total engine management system that controls fuel, air and spark. Privately labeled for MasterCraft, the Tour Edition features throttle-body EFI, a 9.1:1 compression ratio and a sealed ceramic circuit board to go with the waterproof Engine Control Module.
MARINE POWER
A driving force in the inboard commercial boat and fishing industry since the 1950s, Louisiana-based Marine Power appeared in our 1997 boat tests with an EFI GM 350-cid V-8 in our American Skier test boat. So look out, the big three inboard manufacturers have some competition. Sources at Marine Power also confirm that the company will be fielding a specialty ski engine in select 1997 Tigi models. The Marine Power SkiPac is a carbureted GM Vortec 350-cid small-block V-8. With a 9.4:1 compression ratio, the SkiPac produces an impressive 307 hp without the added complexity – or expense – of EFI.
MERCRUISER
As a follow-up to its hot Black Scorpion introduced in '96, MerCruiser has entered the limited-edition high-performance inboard fray with the Scorpion 377. In this case, 377 stands for both 377 crank-shaft hp from a 377-cubic-inch stroker small-block. Better yet, the balanced and blueprinted, port-injected V-8 makes 400 foot- pounds of torque. The Scorpion 377, built by Mercury Marine's high-performance division in Fond du Lac, Wisconsin, also sports what Merc is calling a “wicked new look.”
MerCruiser's Black Scorpion is back in '97 too. The Magnum Gen+ 350 utilizes a 9.4:1 compression ratio, roller-cam valve train, corrosion-resistant multi-port fuel injectors and a big-bore 75-millimeter single-blade throttle body to meter air intake. Black Scorpion S-shaped exhaust pipes help scavenge the engine and are designed for exhaust routing below the tranny mounts. All this results in 315 prop-shaft hp and 365 foot- pounds of torque.
While the Black Scorpion and Scorpion 377 will draw most of the attention this year, the rest of MerCruiser's '97 lineup is what will be pulling most of the skiers. Big-block barefootin' fans will be glad to hear the 395-hp 454 Magnum MPI is still in the line for 1997. On the small-block side, MerCruiser is fielding three 5.7L V-8s below the Black Scorpion; the 290-horse 350 Magnum EFI Gen+, 265-hp 350 Magnum Tourney Ski and the 215-hp 5.7L Competition Ski. Both 350 Magnums get the free-flowing S-pipe exhaust system introduced on the Black Scorpion for 1997.
PLEASURECRAFT MARINE
Late-breaking news out of Little Mountain, South Carolina, is that Pleasurecraft Marine has released its own high-output version of the GM Gen1+ 5.7L V-8. Called the 5.7 MPI APEX, PCM's hot new offering cranks out 320 hp and 375 foot-pounds of torque, due in part to the high-rise GM intake plenum. The 5.7 MPI APEX features multi-port fuel injection and, according to PCM, is equipped with more features and benefits than any other Gen1+ inboard on the market. A fully integrated engine management system ensures optimum performance and durability by controlling all major engine functions. With multi-port EFI, the APEX delivers instant starts, hot or cold, quick throttle response and superior overall drivability and fuel efficiency.
PCM
's patented Fuel Control Cell (FCC) serves both the function of filtering fuel and preventing vapor locks. The design is easily serviced yet combines a submersible high-pressure fuel pump, fuel contamination filter and water separator all rolled into one compact unit. Other 5.7 MPI features include Adjust-a-Flex rubber/stainless engine mounts and a brass-bodied belt-driven water pump. Of course, you get PCM's highly regarded Power Plus transmission, which, according to PCM, delivers 10 percent more torque and better fuel efficiency at half the weight of other inboard transmissions.
The rest of the PCM line remains intact for 1997 as well. PCM's venerable Pro Boss GT-40 delivers an honest 310 hp and 375 foot-pounds of torque, thanks to the use of Ford's free-flowing GT-40 cylinder heads. These are the same heads used on many winning Ford V-8-powered race cars over the years. When teamed with multi-port EFI, they really work to increase the power of Ford's bulletproof 351.
Both the 5.8 and big-block 7.4 HO remain in the engine line for 1997. On the GM side, PCM's Pro Ski 5.7 HO EFI makes 275 hp and a solid 355 foot-pounds of torque, thanks to throttle-body EFI and a healthy marine-grind roller cam. PCM's mix of both GM and Ford engines give the company the most diverse inboard engine line in the industry.
