2022 115hp Tohatsu MFS115A outboard engine review

Tohatsu has always enjoyed a loyal, if not large following in Australia. Back in the two-stroke outboard days, Tohatsu outboards were renowned for being relatively simple in design, but strong, reliable, and powerful; Tohatsu engines were always popular with commercial operators and experienced recreational boaters.

As a teenager, I spent a lot of time fishing and zipping about Sydney's Pittwater in a Stessl tinnie with a Tohatsu 15hp two-stroke outboard engine on the back. This terrific portable motor always started first go, and never missed a beat.

Later, while testing a group of 15hp portable two-stroke outboard engines, it came as no surprise to me to discover an evolution of my original 15hp Tohatsu motor smashed its more popular rivals for performance.

Tohatsu outboard engines have always been strong, robust, and powerful. Today's four-stroke models retain these traditional attributes, but the latest-tech engines are also sophisticated, refined, smooth and economical.

Tohatsu has launched a number of new outboard engines in recent years, all featuring the latest technology, features and functions.

A year or so back we tested the impressive, and lightest-in-class 60hp Tohatsu four-stroke. For this review, we have sampled the larger 115hp four-stroke outboard engine, the MFS115A, paired with a Makocraft 591 Island Cab.

As noted in the introduction, the MFS115A is one of five new mid-size Tohatsu four-stroke outboard engines. The others include the MFS75A, 90A, 100A, and the just-launched MFS140A.

Each has an in-line four-cylinder configuration displacing 1995cc with an unusual 16-valve single overhead cam design.

Rival outboard engines in this class have either a an eight-valve single overhead cam configuration or a twin-cam design with four valves a cylinder for a total of 16 valves.

Tohatsu opted for a single overhead camshaft design for simplicity, ease of maintenance and reduced weight, but with four valves per cylinder for maximum performance, and reduced fuel use at high revs.

Engine torque is key to the performance of the new Tohatsu engines. To gain power and torque across the rev range, rival brands use big engine displacements, which adds weight. Instead, Tohatsu has introduced an industry-first four-into-one exhaust system.

This "Performance Tuned" 4-2-1 exhaust can be likened to fitting extractors/headers on a car to gain performance.

In the new Tohatsu outboards, exhaust gases are directed from cylinders one and four into one pipe, and cylinders two and three into a second pipe, before merging into one outlet. This exhaust configuration provides improved exhaust flow and efficiency compared with a regular 4-to-1 set-up.

With the Performance Tuned exhaust system, maximum torque is developed at lower revs when compared with most rival outboard engines, making for better hole shots and allowing boats to more easily hold a low-speed plane in rough weather.

As well, each of the four cylinders in these engines has an equal-length exhaust passage to provide strong, consistent performance throughout the rev range.

Other features to boost performance include an even-length alloy intake manifold, and "fine-tuned" ECU programming to optimise the air/fuel mixture for maximum acceleration when you gun the throttle.

Spark plugs placed in the centre of each combustion chamber are also said to provide the most efficient combustion with optimal heat conduction for improved performance and fuel efficiency.

With regard to engine weight, the Tohatsu MFS115A is on par with rival 115hp outboard engines at 178kg for the lightest model.

By comparison, the lightest of the 115hp outboard engines is the Mercury at 163kg. The Yamaha 115hp is next best at 171kg, with the Suzuki weighing 182kg and the Honda hitting the scales are at a more portly 218kg.

The smaller 75/90hp versions of the new Tohatsu engine are heavier than some rivals as they weigh the same as the MFS115A but produce less power.

The Tohatsu MFS115A is available in two standard sizes, longshaft 508mm (20-inch) and extra-longshaft 635mm (25-inch).

There's also a tiller-steer version that uses Tohatsu's latest Multi-Function Tiller handle with Grip-End power trim/tilt switch.

Similar to the standard models, the tiller-steer Tohatsu 115hp has a five-step variable idle speed control that should prove ideal for low speed trolling.

The MFS115A is available in two colours — regular Tohatsu Aquamarine Blue or the optional Beluga White.

Tohatsu dealer, Tim Stessl Marine, has advised that pricing for the MFS115A starts from $19,990 for a standard blue longshaft model with a standard rigging kit, alloy propeller and installation.

Buyers can option this engine with regular analogue engine gauges, or with Tohatsu's latest TOCS 4.3-inch LCD digital display. This Tohatsu Outboard Communication System provides access to the full range of engine data, from revs, speed and fuel flow to engine temperature, battery voltage, oil pressure, and more.

The TOCS system also integrates with Garmin multifunction displays to show engine data on a larger screen.

A broad range of other convenience and durability features come with the latest Tohatsu 115hp outboard. They include a high-output 41-amp alternator for running electronics; a low 2:08:1 gear ratio; adjustable steering friction/trim tab; easily removable top cowl; screw-off canister oil filter with drip/catch tray; easily accessed dipstick and water separating filter; built-in freshwater flushing system; a camshaft-driven trochoid oil pump for long term durability; stainless steel water pump housing; new, improved gearcase with a wider splash and anti-ventilation plate; auto-tensioning timing belt adjuster; and more than 16 corrosion-fighting sacrificial anodes placed throughout the engine and major components.

Service intervals for the Tohatsu MFS115A are similar to other four-stroke outboard engines. After an initial 20-hour/three-month service for checks and minor adjustments, the service schedule runs annually or every 100 operating hours.

Specific servicing costs were not disclosed, but we would expect the charges to be comparable with other four-stroke outboards in this size range.

The Tohatsu MFS115A outboard engine is ideal for powering all manner of trailer boats in the 5.0-metre to 5.8-metre size range. We tested it on the back of a 6.0-metre Makocraft 591 Island Cab, a plate alloy craft that is arguably a bit big for a 115hp outboard engine of any brand.

Nevertheless, the diminutive but powerful Tohatsu performed admirably during our sea trial on the Gold Coast Broadwater.

The Makocraft/Tohatsu engine combination lacked only top speed, topping out at a modest 29.1 knots at 5500rpm.

Elsewhere, from low revs through to the mid-range, the Tohatsu proved to be more than adequate for the big Makocraft plate boat.

This is a credit to the excellent performance of the Tohatsu 115hp test engine given that a 6.0-metre boat would normally run with 130hp as a bare minimum.

With two adults onboard, and running a 16-inch pitch stainless steel prop, the Tohatsu accelerated the Makocraft enthusiastically from idle, jumping the boat quickly onto the plane and into the mid-rev range.

Between 3000rpm and 4500rpm the Tohatsu felt responsive, with ample power and torque to accelerate the boat between waves during bar crossings, and to power out of wave troughs in a following sea.

Like all good four-strokes, the MFS115A runs smoothly, quietly, and with no vibration or oil smoke.

The 115hp Tohatsu is also miserly on fuel, achieving maximum economy on the Makocraft whilst cruising at 4000rpm for a boat speed of 20.3 knots, a fuel burn of 20.1L/h, and a range on 95 percent of the boat's 250-litre fuel supply of 240nm.

Performance

Range on 95% of the 250L fuel supply: 240nm at 4000rpm

The Tohatsu MFS115A is an excellent new outboard engine from Japan's oldest outboard engine manufacturer. Despite its modest displacement, this motor has ample power and torque for powering a broad range of trailer boats.

This modern, sophisticated outboard engine is ideal for repowers and installations; the slim, lightweight and compact dimensions of this engine make it ideal for hulls that are weight-sensitive in the stern.

The MFS115A is smooth, quiet, vibration-free and good looking. It looks a treat in traditional Tohatsu blue and in the optional Beluga white. Tohatsu is onto a winner with this terrific new model — and this series of outboard engines.

Supplied by: www.timstesslmarine.com.au