Mercury FourStroke outboards

We spent a couple of days reviewing several new engines in the new Mercury FourStroke outboard motor range

As I approach my twilight years, I crave a simple lifestyle. And outboard engines that are straightforward to maintain and service.

Although I’ve always preferred DFI two-strokes over four-strokes above 60hp, Mercury’s new F80 to F115 FourStroke outboards are the first four-strokes I’d seriously consider buying in this power range. All are based on a four-cylinder 2065cc engine that has roller cam followers (no valve clearance adjustments) and a single chain-driven overhead camshaft, making them no more complex to service than a DFI two-stroke. All are over square, (the cylinder bore is greater than the stroke for lower piston speeds), unlike the marinised car engines in this power range.

A combination of extremely low copper content alloys also gives a long life in saltwater and by reshaping the gear case torpedo to have a more pronounced profile hydrodynamic, drag is reduced by 15 per cent. All maintenance points such as the sump oil dipstick and canister oil filter are easily reached on the clean powerhead layout.

Because the camshaft lobe profiles have been designed to provide maximum torque well down in the rpm range, all the models use more fuel at Wide Open Throttle than their direct four-stroke competition. But in the 80 to 115hp outboard motor market, good holeshot and midrange fuel efficiency are more important than top-end efficiency. I’m sure most buyers can live with this compromise!

Unlike DFI outboards the new four-strokes are quiet and there’s no oil smell when backing upwind. And they are light too with even the Mercury F115 weighing in at 163kg, less than the direct four-stroke outboard competition which has much smaller displacement powerheads.

Videos: Mercury FourStroke outboard motors

We spent a couple of days reviewing several new engines in the new Mercury FourStroke outboard motor range. We tried several configurations on different models and also compared the new FourStroke outboards to the older Mercury models. Our video crew was kept very during the entire multi-day shoot, as was engine expert Andrew "Engine Man" Norton and our 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 F90 FourStroke outboard Loads of low-down grunt and efficient running made the F90 FourStroke Andrew “Engine Man” Norton’s pick of the lot.
	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.