All the 30hp outboard engines compared

Honda reckons its BF30 outboard engine was so quiet when it was developed that there was no need to put sound insulation in the cowling. That’s a pretty big flex straight out of the box.

This is the only outboard engine in this class to use carburettors – three of them – instead of the more modern electronic fuel injection system. It means the BF30 has less ability to control the amount of fuel flowing into the engine’s cylinders, so its ability to automatically tune the fuel flow to get either peak performance or the best fuel economy is not as refined.

The Honda engine is second only to Yamaha’s F30 in terms of displacement. It’s also the only engine in its class to run a longer stroke that, generally speaking, improves the engine’s low-down and mid-range torque but reduces the peak revs. 

Honda has designed this engine with separate short intakes for all three cylinders, hence the need to use the same number of carburettors. This makes the engine more responsive than if it had a single carby with long intake channels.

While the engine does not have electronic fuel control, it does have ignition timing, which means it can manage the spark plug to deliver the best performance.

The engine has an automatic choke and Honda’s engine Alert System that uses alarms you can see and hear, as well as a limp-home mode if the engine is overheating, has low oil pressure or has over-revved. There is also an emergency pull cord to start the engine manually.

The tiller steer version of the Honda BF30 has the tiller mounted in the centre, making it ambidextrous, and has the shift controller mounted on the handle. Forward control, with an optional tachometer, trim gauge and a low oil/overheating warning lights on the throttle and shift lever, is available.

Honda uses four layers of paint on its engines, with two of them forming protective barriers to minimise corrosion. Flushing the engine out requires you to cover the water intakes on either side of the drive leg and under the cavitation plate with duct tape and taking a screw out of the leg to fit a garden hose attachment. Otherwise, you have to place the engine in a bucket of water.

If you don't want the power tilt system, Honda can also fit the engine with an optional gas assist tilt system that makes it much easier to bump the engine up to run in shallow water. 

Specifications
Model: Honda BF30
Engine type: 4-stroke SOHC 6-valve
Cylinders: In-line 3-cyl
Fuel delivery: Carburettor
Weight: 70.5kg (lightest model)
Displacement: 552cc
Bore x stroke: 61.0mm x 63.0mm
Maximum output: 30hp@6000rpm
Operating range: 5000-6000rpm
Shaft length: 381mm (15-inch), 508mm (20-inch)
Alternator: 4A (manual start)/10A (electric start)
Trim method: Manual trim/tilt (std, power opt)
Gear ratio: 2.08:1
Tiller-steer model: Available
Servicing: Annually (or every 100 hours after first service)
Emissions rating: CARB three-star
Warranty: 7 years (5 + 2 recreational use)
More information: www.marine.honda.com.au

Since it was updated in 2022, Mercury claims to have the lightest 30hp outboard engine on the market. Suzuki would probably disagree with that.

Mercury has fitted its 30hp outboard engine with electronic fuel injection that can precisely control the amount of fuel entering the engine’s cylinders depending on whether it needs to increase power or eke out fuel savings. However, a big point of difference for anyone interested in the pull-start version is that the engine does not need a separate battery to power the EFI system.

Electric-start versions of the engine come standard with Mercury’s SmartCraft system that can push information to a smartphone on the health of the powerplant in real time. It will also allow users to push engine data to any compatible Garmin, Lawrence, Raymarine or Simrad multifunction chart plotters and fishfinders.

SmartCraft will also allow users to have precise control to set the engine’s revs, as small as 10rpm increments, important when trolling for fish.  

The three-cylinder, single-overhead-cam Mercury engine features oversquare cylinders that help it perform at higher revs. Stick-steer versions use a much more user-friendly tiller that uses backlit icons to deliver information to the skipper.

The tiller is also more user-friendly to left- and right-handers, and is able to swap from side to side to suit the user’s needs. That includes the tiller-mounted shift and throttle controller.

There are no analogue gauges for this engine, so you’re either going to push data to your smartphone (tiller steer), a Mercury VesselView interface, or a compatible chartplotter. You can also troubleshoot problems using this connection, or even send information to Mercury to find out what to do next.

The engine is well equipped with electronic smarts, so it's good to see that the Mercury is equipped with the best recharging capacity of this class, all 17 amps of it.

Mercury has also designed this engine so that you can change the oil in the gearcase with the engine tilted to any position. Engine oil can be topped up via a no-spill system, and filters are all in easy-to-access areas of the engine to help with periodic maintenance.

You can flush this engine with an earmuff-style attachment that slides over the water intakes.

Mercury offers this engine with a gas-assisted lifting mechanism for owners who don't want power tilt and trim, but want help with tilting it for shallow-water applications.

Specifications
Model: 30hp Mercury FourStroke
Engine type: 4-stroke SOHC 6-valve
Cylinders: In-line 3-cyl
Fuel delivery: EFI
Weight: 65.7kg (lightest model)
Displacement: 526cc
Bore x stroke: 61.0mm x 57.0mm
Maximum output: 30hp@6200rpm
Operating range: 5800-6200rpm
Shaft length: 381mm (15-inch)
Alternator: 17A
Trim method: Manual trim/tilt (std, power opt)
Gear ratio: 2.17:1
Tiller-steer model: Available
Servicing: Annually (or every 100 hours after first service)
Emissions rating: CARB three-star
Warranty: 6 years (3+3 recreational use)
More information: http://www.mercurymarine.com

Here is another lightest-in-class claim, and this time it stands up to boatsales scrutiny. The Suzuki DF30A is a bit different to other outboard engines in this class in that it uses an offset driveshaft that moves more weight inboard, offering a better balance and allowing the engine to swing bigger props, and an offset crankshaft that reduces lateral pressure on the cylinder.

One of the other innovations in this engine was the adoption of roller rocker arms to reduce friction losses – a first in this engine class.

This is also an engine fitted with electronic fuel injection that does not need a battery to power it, meaning the tiller steer, pull start version of this outboard weighs in at just 70.0kg. For those who prefer pull-start, Suzuki has fitted a recoil starter that needs much less effort to pull than a conventional set-up.

To help owners manage the health of the DF30A, Suzuki has fitted the face of the engine with three LED lights that light up to warn of extreme coolant temperature, low oil level or some other fault that forces it into limp-home mode. The engine will also flash its oil light when a service is due.

Suzuki has also been clever about the way owners clean the DF30A, fitting it with an easy-access engine flush port so they just need to connect a hose while it is shot down rather than fit earmuffs or fill a bucket and start the engine.

Suzuki’s version of its electronic fuel injection uses Lean Burn Control to improve fuel efficiency. It monitors engine performance and operating conditions to vary the amount of fuel injected into the cylinder.

The Suzuki DF30A comes as either a tiller steer with the gear shifter located on the front of the engine, or as a forward control with a console or coaming-mount shift and throttle lever.

The engine does come with a manual start rope, but accessing the flywheel takes a bit of surgery.  It can also lock up on an angle that makes it useable in shallow water.

If you want the engine to talk to your multifunction chartplotter, you’ll need to install an NMEA 2000 interface that sits between the engine and your console.

Suzuki’s 30hp outboard engine is pretty good at looking after onboard electronics, providing up to 14 amps of charging power at running speeds.

Specifications
Model: Suzuki DF30A
Engine type: 4-stroke SOHC 6-valve
Cylinders: In-line 3-cyl
Fuel delivery: EFI
Weight: 62.0kg (lightest model)
Displacement: 490cc
Bore x stroke: 60.4mm x 57.0mm
Maximum output: 30hp@6300rpm
Operating range: 5300-6300rpm
Shaft length: 381mm (15-inch), 508mm (20-inch)
Alternator: 14A
Trim method: Manual trim/tilt (std, power opt)
Gear ratio: 2.09:1
Tiller-steer model: Available
Servicing: Annually (or every 100 hours after first service)
Emissions rating: CARB three-star
Warranty: 6 years (3+3 recreational use)
More information: www.suzukimarine.com.au

Yamaha is a little different to the other outboard engine makers in this class in that instead of making the 30hp engine the most powerful for its displacement – one engine can come in several different states of tune – Yamaha's is the least powerful in its engine family.

What that means is that the F30 has the largest displacement in its class, beating the capacity of its nearest rival by a healthy 35 percent.

But it also means that the Yamaha is the heaviest in its class, tipping the scales at close to 100kg and limiting its use for smaller boats with smaller transom load limits.

That said, part of that weight is standard electric start and power tilt and trim, so you get a premium product by default. You also get 17 amps of recharging performance.

Yamaha's F30 uses electronic fuel injection to control the amount of fuel each cylinder is burning, meaning it can maximise fuel efficiency, and then stack on the performance when power is needed.

Yamaha's F30 also has a variable-speed trolling mode, with skippers able to adjust the revs in 50rpm increments from 650 to 900rpm. They can do this either via a toggle switch on the tiller or the Command Link/digital gauge for forward-control installs.

Yamaha claims it uses a special alloy to cast its engines that helps with protecting against corrosion. A long airflow path on the intake manifold helps to boost low-speed torque, while rubber mounts help isolate vibration and harshness coming from the engine to the boat via the transom bracket.

One of the most user-freindly features of this engine is a freshwater flushing port built into the cowling that makes it very easy to connect a hose and flush out any salt build-up without the need to run the engine.

This engine is also compatible with a range of Yamaha's digital displays and gauges.

Specifications
Model: Yamaha F30
Engine type: 4-stroke SOHC 6-valve
Cylinders: In-line 3-cyl
Fuel delivery: EFI
Weight: 98.0kg (lightest model)
Displacement: 747cc
Bore x stroke: 65.0mm x 75.0mm
Maximum output: 30hp@6000rpm
Operating range: 5000-6000rpm
Shaft length: 508mm (20-inch)
Alternator: 17A
Trim method: Power trim/tilt 
Gear ratio: 2.00:1
Tiller-steer model: Available (opt)
Servicing: Annually (or every 100 hours after first service)
Emissions rating: CARB three-star
Warranty: 4 years (2+2 recreational use)
More information:www.yamaha-motor.com.au