“Horsepower Highway” is where our 525 EFI, 565, 600 SCi , 662 SCi and 700 SCi sterndrive engine family is built. One technician hand builds each engine from a bare cylinder block to a “long block” (with all the rotating and reciprocating bits fitted inside). Sub-assembly work prior to an engine build includes the rotating assembly: balancing a crankshaft, matching it with a camshaft, pistons, rings, and connecting rods for later fitment into the block.
Horsepower Highway was conceived, engineered and built in-house. It features a unique rail system and assembly fixtures used to transport cylinder blocks along the line. At each station, all the required tools and components are located for assembly. Each technician controls the speed of his build, moving the block along at their own pace. If something doesn’t look right, it is his discretion to stop right then and there. The build begins with installation of a camshaft. Next is the installation of a crankshaft, timing chain and matched piston and connecting rod sets. The bottom end is sealed with the installation of the oil pan.
The engine is rotated on its assembly fixture to enable work on the top end: The cylinder heads are installed; then push rods and rocker arms. Temporary valve covers mask the valve train prior to paint. An intake is the last component installed before the long bock goes to our paint line. Upon return from paint, it goes back on The Highway for installation of a bell housing. Color matched valve covers replace the temporaries to complete valve train assembly. Transmissions for NXT1 or NXT6 drive models are installed at this point as well.
Long blocks for various engine models look similar. One noticeable difference is the intake (long blocks with naturally aspirated intakes are destined to become 525 EFIs or 565s; those with pressure charged intakes will become 600/662 or 700 SCi’s). Custom color long blocks stand out, too. The “dress line” is where an engine get its true personality.
Here, long blocks are fitted for life on the water. Every component needed to make an engine come to life and maintain good manners is added here. Components include closed cooling, electronic fuel injection, power steering, electrical harnesses, ignition systems and a Propulsion Control Module (PCM) – the brain behind the brawn. 525 EFI and 565 models get their respective naturally aspirated intake systems; pressure charged engines are fitted with a screw supercharger and an electronic boost bypass control valve. When the build is completed and the last zip-tie is snipped, an engine is ready for the dyno.
A 4-cycle dyno is where each and every one of our high performance sterndrive engines is tested. Engines roll into a dyno room where a technician preps them for a run. Every engine is evaluated for an hour or more – through its full RPM operating range – and compared to Racing’s standards for function and power output.
Upon successful completion of its test run, engine oil is changed and it is rolled out to Shipping. The engine is boxed for transfer to Mercury’s distribution warehouse. From there engines will ship, with their drive and transom mates, to either a boat builder for installation in a new hull or a Mercury dealer for replacement of tired engines in an existing boat. Either way, they are sure to delight their new owner.