Volvo Penta D1-13 review
My life is full of singles: portable generators, lawn mowers, brush cutters and other power equipment. And they work fine because they’re not enclosed in a fibreglass boat hull.
But if your compact cruising yacht needs a marine engine repower, don’t inflict pain on yourself by fitting another single-cylinder diesel. Compact twin-cylinder industrial and tractor-based engines for bats are so smooth-running and torquey compared to the singles of old it’s sheer lunacy fitting another one.
Older yachts such as the Top Hat 25 and Compass 28 were fitted with singles because that’s all there were in the seventies. Single-cylinder four-strokes suffer from “cyclical slowing” where as the rpm increases, the engine slowing during the exhaust and intake cycles becomes more pronounced. This translates directly to increased vibration and we all know how efficient fibreglass is at transmitting this through the hull and deck structure. I well remember a mate’s Endeavour 26 visibly shaking during certain rpm ranges of its single-cylinder diesel. Sheer misery for extended motoring!
Twin-cylinder diesels have alternate firing and as the rpm increases vibration decreases, particularly above 2000rpm. And the Volvo Penta D1-13 is a fine example of what can be accomplished in a compact twin.
VOLVO PENTA D1-13
The D1-13 is Volvo Penta’s smallest diesel and develops 11.8hp at 2800 to 3200rpm from its 510cc engine. Based on a Japanese Shiibaura tractor engine, the slightly under-square design with 67mm bore and 72mm stroke gives good combustion chamber efficiency and, combined with the indirect injection, low exhaust emissions. The only drawback is the high 23.5:1 compression ratio but Volvo Penta acknowledges this by not fitting hand starting, so you won’t be red faced if you try to show your female passengers how strong you are and fail to start the engine!
Like all small tractor and industrial engines the OHV D1-13 has a gear-driven camshaft with pushrods to actuate the rockers. So simple and reliable.
Heat exchanger cooling on the Volvo Penta D1-13 is standard and the exhaust manifold is cooled by freshwater, so if there is a leakage only freshwater can reach the combustion chambers. The seawater pump is gear driven, with a single-belt drive for the freshwater pump and alternator. Pumping out a maximum of 115amp, this voltage regulated unit still produces 100amp in the 2000 to 2500rpm range.
The Volvo D1-13 is available with two multi-disc clutch gearbox options or a saildrive. With the standard eight-degree down-angle box the combined dimensions are 651mm long, 488mm wide and 514mm high, lower than the direct competition and the dry weight is 113kg. This is almost 20 per cent lighter than the old seawater cooled single-cylinder diesel of the same output and piston displacement popular with the Compass 28.
The straight-output box is 1kg lighter and both have the choice of 2.35:1 or 2.72:1 reduction ratios. The 130S saildrive option adds 13kg and has only a dog clutch but at least the gear oil can be changed from inside the hull, while split zinc anode on the gearcase torpedo can be replaced without removing the prop.
Servicing intervals on the Volvo Penta D1-13 are every 100 hours or annually and I recommend using SAE 10W30 oil in cooler climates or SAE 15W40 oil in the tropics. If your yacht is used infrequently then the oil and filter should be changed every six months, as lubricating oil degrades faster through disuse than constant use.
The exhaust manifold is to port of the engine, so you may need to run the exhaust pipe over to starboard after it leaves the water lock silencer if your boat is fitted with one of the old single-cylinder Japanese engines. Standard instrumentation includes a start button or key switch with alarm for high coolant temperature, low oil pressure and alternator charge failure. A tachometer and hour meter are optional but in my opinion essential, as you should always know the rpm instead of relying on black exhaust smoke to tell you the engine is overloading. The D1-13 should reach 3200rpm under normal cruising conditions.
TORQUE AND FUEL BURN
Remarkably for a mechanically injected diesel, maximum torque of 29Nm is available from 1800 to 2800rpm, with 26Nm at only 1200rpm and 27Nm at 3200rpm. This gives the D1-13 plenty of grunt for manoeuvring a yacht in a crowded marina.
Unfortunately I’ve yet to review the Volvo Penta D1-13 in a yacht and the following figures are based on standard displacement-speed prop power curves. Naturally aspirated diesels have a maximum efficiency of 36 per cent with prop losses reducing this to 21 per cent, but when idling the overall efficiency may be as low as two per cent. This is why the fuel flow at lower rpm seems so high in relation to the prop output.
THE TRADE-A-BOAT VERDICT
The D1-13 shows how far small diesels have come in the past 30 years and Volvo Penta has always understood what yachties want in an auxiliary engine. Fit one of these to your compact cruising yacht and it’s goodbye blurred vision! For more information on the D1-13 contact Volvo Penta Australia or call (07) 3726 1500.
PROP POWER-FUEL FLOW
11.8hp Volvo Penta D1-13
RPM PROP HP FUEL FLOW (LT/H)
1800 2 0.7 (min cruise)
2600 6.2 1.6 (ideal cruise)
2800 7.9 2 (max cruise)
3200 11.8 3.1 (Wide Open Throttle)
VOLVO PENTA D1-13 SPECIFICATIONS
TYPE Two-cylinder diesel marine engine
RATED HP 11.8
DISPLACEMENT 510cc
WEIGHT 126kg (dry w/ saildrive)
BORE x STROKE 67 x 72mm