Over the past couple of years the marine industry has made the commitment to the refined technology first developed in the 80′s by the automobile industry, electronic fuel injection. These engines provide the power of a big block engine with better fuel efficiency and less weight.
Fuel-injected engines also offer something carburated engines never could: self-adjustment and less maintenance. A computer-controlled engine will adjust fuel mixture to compensate for different atmospheric pressures.
Fuel injection also reduces maintenance time. “On an EFI system, you don’t have to drain the fuel system when you put it up,” says Carl Seyerle, engineering director for Indmar Engines, adding that there is no evaporation in a pressurized EFI system. “You will get some separation over time, but you’ve got a combustible mixture the first time you key up.”
Among the company’s new offerings for 1998: a carbureted and a fuel-injected 5.7-liter GM V-8. These engines replace earlier 275-horse versions of 5.7-based inboards. Both Gen1 Plus-based engines are equipped with high-flow cylinder heads and pump out more than 300 hp each. Fuel-injected models are equipped with the patented Fuel Control Cell, a two-pump filtration system PCM says eliminates vapor lock.
Another upgrade is the Adjust-a-Flex II Engine Mounting System, a new feature that allows for a much smaller engine box. It uses heavy-duty mounts and noncorrosive stainless steel trunnions and rubber isolators.
Whether GM- or Ford-based, PCM engines use Power Plus transmissions, which come in direct- or gear-reduction drive.
Idmar modified its fuel-injected 5.0-liter V-8 and now boasts a new Indmar-designed, dual-plane intake manifold. When combined with Gen1 Plus high-flow cylinder heads and throttle-body injection the engine delivers a broader power band with more torque available at low to midrange RPM – where ski boats need it most. The engine features a 9.1:1 compression ratio, yet still runs on 89-octane gasoline, reducing overall fuel costs. MasterCraft’s new economy model, the SportStar 19, comes standard with this engine, which is backed by Indmar’s new three-year limited warranty that goes beyond the block and internals to cover fuel and electrical systems.
Step up to 5.7 liters and Indmar offers its newest Tour Edition, privately labeled for 1998 MasterCraft Boats. Indmar bumped up compression to 9.4:1, yet the engine also runs on middle-grade 89-octane. The Tour Edition also uses the high-flow cylinder heads and Indmar-design dual-plane intake manifold.
Using General Motors’ multi-port injection in its 5.7 Gen1 Plus HO engine that debuted on the Chevrolet Corvette, Indmar ups the ante a bit further. Multi-port fuel injection uses one injector per cylinder, compared with throttle-body’s two-injector setup, and allows a more precise, timed blast of fuel to enter the cylinder. Port injection uses the same three-dimensional engine management system custom-calibrated by Indmar. The system uses GM’s waterproof engine control module featuring a sealed ceramic circuit board developed specifically for marine use.
Indmar’s flagship engine, the Tour Edition 5.7-liter LT-1, also has been massaged for 1998. In addition to a new Indmar-designed high-torque camshaft, the LT-1 uses 1.6:1 ratio rocker arms. The increased ratio opens valves a bit farther, allowing more fuel to enter the cylinder. The LT-1 is fitted with aluminum cylinder heads and a 10.25:1 compression ratio, yet runs on pump gas. Normally, when engine compression ratios approach 10 points or greater, they require higher-octane fuels because of higher combustion temperatures. This is not the case with the LT-1. Its reverse-flow cooling system cools the cylinder head-first – where combustion occurs – and allows for higher compression ratios without the need for more expensive, high-octane fuel.
Editor’s note: Because of the disparity in industry practices of measuring horsepower and torque (plus or minus 10 percent), Indmar has a policy of not publishing such information.
MerCruiser offers four engines designed for inboard ski applications. From a carbureted 260-horse model to its fuel-injected, 360-horse Scorpion, MerCruiser has an engine to fit nearly every niche.
Its 260-horse, 5.7-liter power plant features a time-tested Rochester two-barrel carburetor, MerCruiser’s Thunderbolt ignition and the company’s new S-pipe exhaust system that lowers the engine profile for increased cockpit space and provides unobstructed exhaust flow.
MerCruiser also offers a 300-hp Mag MPI and a 315-horse Black Scorpion. Each is multi-port fuel-injected and features MerCruiser’s knock control and water/fuel separator. They’re also equipped with a water-cooled fuel system, which reduces vapor lock, a condition that vaporizes liquid fuel before it enters the combustion chamber, causing immense power loss.
MerCruiser’s most powerful engine, the Scorpion 377, builds 360 hp, in part by using an old hot rodder’s trick. To achieve a cubic-inch displacement of 377 inches, engine builders would take the crankshaft from a 400 and put it in a 350 – or 5.7-liter – block. That increased the stroke length to 3.75 inches and bumped up the displacement by 27 cubic inches. The hand-built Scorpion engine is blueprinted and topped with cosmetic touches such as steel-braided lines and a polished blue intake plenum to make it look as good as it runs.
Call them the little engine company that can. Marine Power has been building inboard power plants for about 40 years. This year the company offers two engines of varying horsepower and fuel-delivery systems and backs each with a four-year warranty.
Its lowest-horsepower offering for 1998 is a carbureted GM Vortec 5.7-liter V-8. This carbureted 310-horse engine is used as standard power in Tig* Boats, built in Abilene, Texas.
The company’s 325 hp throttle-body injected model also is based on GM’s Vortec. This engine comes standard in the American Skier line of boats.