Mercury F90 Fourstroke Outboard Motor
Fourstroke super star by Mercury
The 90hp Mercury FourStroke outboard motor is my pick of the new Mercury FourStroke engine range. Maximum torque is developed at only 3000rpm with plenty of torque at 2000rpm, which means there’s a ton of grunt down low. This outboard motor is available in standard and CT gearcases.
The FourStroke 90 hp Mercury develops 89.8bhp at 5500rpm and is almost as quick as the Mercury F115, but way more fuel-efficient relative to output, even at or near WOT.
Mounted on a Stacer 509 Searunner cuddy cab (one of my favourite hulls), the demo standard gearcase F90 90hp Mercury had instant throttle response to maintain the right position relative to waves coming back in through the Gold Coast Seaway where we tested the engine. Like the Mercury 115 outboard, the power trim was quick and the Stacer 509 could be trimmed rapidly to suit sea surface conditions.
Across its entire rpm range the Mercury F90 outboard was quiet and vibration free, even though its large displacement powerhead doesn’t have counter-rotating balance shafts. Power astern was good too, with no need to open the throttle in reverse coming alongside a jetty.
Videos: Mercury FourStroke outboard motors
We spent a couple of days reviewing new engines in the new Mercury FourStroke outboard motor range. As you can see, our video crew was kept very busy, as was engine expert Andrew "Engine Man" Norton and senior boat tester, John "Bear" Willis. Here's what they had to say.
Mercury F80 FourStroke outboard
Don’t stress over this outboard wearing out. The Mercury F80 develops maximum power at just 5000rpm, way lower than competing engines.
Mercury F115 FourStroke outboard
The F115 is quieter than its predecessors due to decreased load on the engine. It also planed faster when fitted with a new Command Thrust gearcase.
Mercury Command Thrust gearcases
The new FourStroke range isn’t just about engines. Mercury also redesigned its engine gearboxes to reduce drag and increase overall performance.
What else is new?
Mercury Australia’s Anthony Brown explains what else is new, from significant engine weight savings to the SmartStart system that won’t wreck the starter motor.