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Talking Torque: High Five

Five cylinders make all the difference

Way back in 1989 while working as a motoring writer, I borrowed a manual Audi 90 for extended evaluation. It was a lovely vehicle to drive, but what really stood out was the 2.3L five-cylinder engine. It was way smoother than a four-cylinder unit (such as the 2.2L in the manual Peugeot 505 I borrowed two years earlier), but not as bulky as an in-line six, plus delivered fuel efficiency similar to a four.

Since then, five-cylinder engines have appeared in other European vehicles, including the Volvo X90 4WD station wagon. The all alloy 20 valve 2.4L diesel has been marinised to provide the base for the Volvo Penta D3-130 and D3-160, which I reviewed in Trade-a-Boat in 2003.

The D3-130 developed 129 brake horsepower at 4000rpm with 280 Newton Metres of torque available from 1750–3000rpm, while the 160 developed 161bhp at 4000rpm and 340NM from 2000–2750rpm. The significant under-square bore to stroke ratio helped develop maximum torque at lower rpm than if an over-square design been used.

IN THE DETAILS

The D3-130 and 160 were the next technological step from Volvo Penta's KAD series of diesels, which had supercharging for increased bottom end torque, with turbocharging to provide more top end power and better fuel efficiency. The system worked well, with hardly any sense of the switch-over, but Volvo Penta found that ‘Variable Geometry Turbo-charging’ was a better and lighter way to go.

VGT works by reducing the pitch of the turbocharger vanes, enabling the turbocharger to ‘spool up’ faster at low rpm until the full effect of the exhaust gas pressure is available. The vane pitch increases as the engine rpm increases, eliminating the need for a separate supercharger or a twin-turbo arrangement, which can be more complex.

Although the 130 and 160 had variable fuel injection timing to eliminate problems of cylinder bore glazing at low rpm, from fuel over-supply inherent in fixed-timing injection systems, opting for high pressure common rail injection in the D3-220 enabled significant gains in maximum torque and power. The 18:1 compression ratio of the 130 and 160 was reduced to 16.5:1 to allow for the injection pressure of 26,500psi or 1800 bar, just about the limit for CR. The 220 complies with Euro Recreational Craft Directive Stage 11 and US EPA Tier 3 exhaust emission regulations.

The result is a rapid torque increase from 1500rpm of 270NM to a peak of 464NM at just 2500rpm, giving excellent hole-shot in planing hulls. The torque from 2000–3000rpm ranges from 420 to 460NM, falling off above these revs. But 340NM are still available at 4000rpm.

The 220hp figure relates to crankshaft output and not prop shaft, unusual for Volvo Penta which normally rates its inboards at prop shaft output. The crankshaft out is 217.2bhp, while the prop shaft output (in the case of Duo prop stern drives) is 206.4bhp. Considering stern drive legs have two power-robbing right-angle drives, the loss of 10.8bhp indicates the stern drive leg is efficient.

A nice feature of the 220 is the rpm limiter until the engine has reached normal operating temperature. The limiter holds the engine down to 1200rpm, preventing engine damage from running it under load until the lubricating oil has fully circulated through the engine and turbocharger.

Sensibly the leg has a cone clutch at the top instead of a dog clutch in the gear case torpedo. The cone clutch makes for smoother shifting and its location means servicing is easier. The cooling water intakes are located just above the torpedo, so for trailerable hulls, fresh water flushing is simpler than through-hull water intakes.

Maintaining the 220 appears straightforward with a serpentine drive belt at the forward end and sump oil filler cap on top with the dipstick to port, just aft of the 180A voltage-regulated alternator. The fuel filter is mounted up high on the port side and all wiring appears to be neatly routed.

The engine-only dimensions are 758mm long, 836mm wide and 751mm high. The leg is 815mm long from the transom to the aft tip of the anti-ventilation plate. 

The dry weight complete with Duo prop leg is 363kg, well under comparable output petrol stern drives which have significantly lower peak torque outputs.

Volvo Penta doesn't stipulate the required sump oil viscosity, but I suggest using a diesel-specific SAE 15W40 oil. However, in cold climates a synthetic SAE 5W30 oil could be used, but I recommend checking the owner's manual for oil viscosities depending on anticipated temperature range between oil and filter changes. Volvo Penta's recommended maintenance intervals are the first 30 hours or three months then every 100 running hours or annually.

ON THE WATER

Fortunately Trade-a-Boat editor Tim van Duyl did an on-water evaluation of the 220 last year in a Whittley CR 2600. He pointed out that trolling at 2.7kt, the 220 used a mere 0.8L/h, and cruising at 21kt and 3000rpm used 27L/h. 

The Wide Open Throttle speed was 31.8kt at 4000rpm using 47L/h, slightly over the 45L/h listed by Volvo Penta because the engine was marginally over-propped and the injection system was pouring in more fuel to compensate for the overloading. Under normal hull, fuel and passenger loading the 220 should reach 4100rpm with a clean hull and props.

Tim also pointed out that electronic throttle and gear shift was easy to use and engine running info was clearly displayed via Volvo Penta's NMEA 2000 compatible system.

THE WRAP

It's strange how only European engine manufacturers love engines with odd numbers of cylinders. Yet there's real merit in five cylinders because they balance better than comparable four-cylinder engines without needing longer engine compartments as in the case with in-line sixes. 

Now, all we need to see is development in seven-cylinder engines, such as the Finish AGCO diesels, which are slightly longer than in-line sixes without the crankshaft torsional issues of straight-eights. 

For more info on the D3-220 contact Seamech in Murrarie, Qld, (07) 3890 7615 or email info@seamech.com.au 


SPECS

Engine: Volvo Penta D3-220

Engine type: Five-cylinder DI CR turbo inter cooled diesel.

Crankshaft output: 217.2bhp/220.3mhp at 4000rpm*

Prop shaft output: 206.4bhp/209.4mhp at 4000rpm

Maximum torque: 464NM at 2500rpm

Displacement: 2.4L

Bore x stroke: 81 x 93.2mm

Dry weight with Duo prop: 363kg

*Brake horsepower/metric horsepower or PS