Engine Review - Beta 90

A long time ago in a way simpler age, my parents gave me my first boat. A 3m plywood rowing dinghy, it allowed my imagination to run wild exploring the quiet bays of Scotland Island in Sydney’s Pittwater where they owned a weekender.

That was in 1965, the same year Laurent Giles & Partners created the 12.2m Salar 40 which was released at the London Boat Show. One of the larger fibreglass yachts of the time the 40 was marketed as a motorsailer, with a full keel, moderate overhangs fore and aft, a masthead sloop rig, centre cockpit and semi-enclosed helm station. What set the 40 apart from the competition was the choice of marine engine, a Perkins 4-236, a massive engine for what was really a heavy displacement cruising yacht. The only drawback of the design was the drag under sail of the large three-bladed fixed prop which couldn’t freewheel due to the hydraulic gearbox fitted.

The 3860cc 4-236 developed 76bhp at 2250rpm and 250Nm at 1600rpm. It also formed the basis of the 3.9lt Izuzu diesel fitted to the 1984 Land Rover County 110 which I tested back then while working as a motoring writer. The engine had tons of bottom-end torque for low-range crawling, but when idling my somewhat less flab than now didn’t stand a chance of hanging on.

Back to the Salar 40, which was so well-built, examples are still on the market. Alas the 4-236 is long gone, so what to fit? This is where the Beta Marine 90 marine engine makes its entrance.

Beta Marine 90 diesel engine

The direct injection naturally aspirated Beta Marine 90 diesel engine may have a smaller piston displacement but due to its more efficient combustion chamber design develops more power and torque. The cast-iron Kubota base engine has a gear-driven camshaft with pushrods operating the overhead valves and heat exchanger cooling is standard.

Though designed primarily as a tractor and industrial engine the Beta Marine 90 diesel has a relatively high-mounted starter motor, while the standard 65amp voltage regulated alternator (120amp optional) is located almost at the top of the engine. As with its other diesels Beta doesn’t fit a shroud over the V-belt that drives the freshwater circulating pump and the alternator, relying instead on operators to use common sense around the engine.

A large cyclonic air cleaner is mounted aft above the gearbox which I presume has a standard 2:1 reduction ratio. The fuel sedimenter with air-bleed pump is ahead of the cleaner next to the inline low-pressure mechanical fuel injection pump. The canister oil filter is mounted on its side so replacing it won’t dribble oil down the cylinder block The sump oil evacuation pump draws oil from the aft end of the sump and with normal installation inclination all the old oil can be removed. Beta Marine is one logical company!

Maintenance

I recommend changing the oil and filter every 100 to 200 hours or annually, depending on how infrequently the engine is used. A diesel-specific mineral-based oil with an SAE 15W40 rating should do the job.

Beta Marine offers four instrument panels, but for a repowering investment of this size I’d opt for the C control panel. This includes an analogue tachometer (damn, to 4000rpm), oil pressure and water temp gauges and a voltmeter, plus alarms for low oil pressure, high coolant temp and alternator charging failure. There’s also a key-operated ignition switch. The panel is 298mm long by 166mm high and in my opinion is worth the bulk and expense for the information it gives.

The Beta Marine 90 diesel has an overall length of 1092mm, width of 639mm and height from engine bearers to a top of 496mm or 758mm including the sump bottom. Beta Marine offers a custom engine bearer manufacturing facility so the new engine can utilise existing engine bearers.

Of course the prop shaft on the Beta Marine 90 diesel may have to be upgraded slightly to handle the additional torque and power, but as maximum power is developed at higher rpm than the 4-236 the existing propeller should be okay. The recreational-usage warranty is five years “self-service”.

The Trade-a-Boat verdict

In addition to repowering the Salar 40 the Beta Marine 90 diesel would also make a good replacement engine for the direct injection four-cylinder Ford 80 fitted as standard to the Clipper 34 trawler yacht, providing it was used only for river and harbour cruising. Just make sure the engine bearers and flexible mountings are up to the task of absorbing the fairly high vibration levels below 1000rpm.

For more on the Beta 90, contact Graham at Beta Diesel Australia, phone (02) 9525 1878 or email sales@betadiesel.com.au.

Beta Marine 90 diesel engine performance

* Minimum and maximum continuous cruising rpm. Like all fixed-timing diesels the 90 must be ‘worked’ to prevent possible cylinder bore glazing from fuel over-supply below the maximum torque band. Sea-trial data supplied by the author.

Beta Marine 90 specs

TYPE Four-cylinder naturally aspirated marine diesel engine

RATED BHP/MHP 90 / 91.2 at 2600rpm

MAX TORQUE 284Nm at 1400rpm

DISPLACEMENT 3769cc

BORE X STROKE n/a

WEIGHT 425kg (dry, w/ gearbox)

See the full version of this review in Trade-A-Boat #470, on sale October 1, 2015. Why not subscribe today?