Mercury’s mid-range 4-Strokes impress
  |  First Published: August 2014

If you’re a user of outboard motors in the 70-130HP range – and plenty of Aussies are – you’d be forgiven for thinking that all of the cool developments in technology and improvement in efficiency happen at the top of the horsepower ranges (in motors from 200HP and more).

And you’d be right in that assumption.

High horsepower motors are developed and targeted for the American market where a combination of bass boats and saltwater boats consume a remarkable number of units.

There’s constant pressure on the big outboard companies to release lighter, faster and more efficient outboards for a lower price point.

Here in Australia, the price of petrol is relatively more expensive than Stateside. With horsepower consumed, the mode is more likely two digits than three in most markets. If you were to guess that a 70HP-class motor is a top seller for any of the major brands, you wouldn’t be too far off the mark.

Therefore, it’s pretty big news here when some of the big motor technology drops down to lower horsepower engines, and the recent launch of Mercury’s big capacity four stroke outboards in the 75 to 115HP class demonstrated that clearly.

Mercury launched a large range of outboards in this range – we assume to provide the range of configurations needed to fit the maximum HP rating on the broad range of hulls built over here. 75, 80, 90, 100 and 115HP models make up the range, with the 90 and 115HP iterations available with the re-designed and re-badges Command Thrust (re-birthed Big Foot) gearcase.

So, before the annual Mercury Dealer Conference at Sanctuary Cove, we (the media) were given a first peek (and drive) of these impressive motors.

You’ll get two levels of reporting here: the layman’s version and a more technical overview of what makes these things tick.


Who remembers the old Merc carburetted two strokes in this horsepower class a decade ago? They were light and had awesome power, but were thirsty, dirty and loud.

These four-strokes are lighter (from 163kg), have better torque and are quieter and more efficient.

Heck, they’re even lighter, punchier and better on the juice than the current range of Mercury OptiMax in that class.

And released at the same price point of the current range of four-stroke offerings, Mercury has really given their consumers little reason to stick with a two-stroke offering.


In a trend that was started by Yamaha’s SHO outboards, big capacity four-stroke technology is moving rapidly through the industry. Departing are the days where a compelling reason not to buy a four-stroke is a lack of punch in the mid range.

These mid-range releases feature a 2.1 litre displacement compared with the 1.5 litres of their Opti Max and 1.7 litres of their existing four-strokes in the class.

“High displacement and light weight; that means great performance. It means that the engine doesn’t need to work hard to achieve its power, so it’s very reliable and durable,” said Mercury’s Steve Miller while taking these motors for a spin on the Coomera River.

“And, these motors are very easy to take care of, to service and maintain, with a valve train that is maintenance free for life,” he continued.

The four-cylinder block has an 8-valve, low friction valve train with a single overhead cam design.

Matching the excitement of Steve about these motors (scan the QR code hereby for the video interview), was the response of the fishing and boating media on the test day and of Mercury dealers.

“As dealers, we’re very excited about this new mid-range product that Mercury’s released. It’s something we’ve been wanting and needing a long time and the proof’s in the pudding out on the water – they’re spectacular,” said Brisbane Marine Mercury dealer, Troy Wood.

“They’re quiet, they’re powerful, they’re smooth, they’re doing everything we’ve all asked for and we couldn’t be more proud to represent them and have the ability to sell them,” Troy continued.

Mercury’s own figures suggest that these units are 14% better on fuel than their current 1.7 litre four-strokes and output 23% more torque.


There’s always been a “Big Foot” option for four-stroke motors in the 40 to 60HP class, renamed “Command Thrust” in these mid-range motors, the upsized lower unit is designed for boats that run with more wetted hull surface than standard and allows propellers from the V6 models to be used. The Commant Thrust gearboxes are available in the 90 and 115 HP

The standard gearcase, though, has also been redesigned to decrease drag by 15% and significantly improve performance. The standard gearcase is the best option for hulls that get up and plane at higher speeds.


It seems simple, but designing a tighter fitting cowling that less water in and less noise out is just one of the ways that Mercury’s engineers have kept this motor quiet.

An idle relief muffler system lessens high-frequency exhaust noise.

A top-mounted throttle body fine-tunes intake noise, while a totally new engine mounting system greatly reduces vibration.

Even the trim pump is designed to run significantly quieter, and a new clutch system reduces shock while shifting into gear.

All of these features deliver a smoother, quieter, more pleasant boating experience.

These engines are shipping now. You can get more information on Mercury’s website: www.mercurymarine.com.au or by visiting your local Mercury dealer. Bottom line is you need to take a ride in these things – you’ll love ‘em.

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