America's Definitive Marine Engine Magazine
Years ago Volvo Penta introduced a 55 horsepower diesel sail motor. Dubbed the D2-55, this vintage engine boasts more low end torque than ought to be legal. Then in fall of 2003 the Swedes have upped the ante by adding an even more powerful variant. The new kid on the block is the D2-75. Suffice to say the new motor is basically the same engine as its predecessor, but with its performance magnified by way of a turbocharger and charged air cooling. The net result, 20 more horsepower.
Just like its little brother, the new D2-75 boasts an enviable emissions profile, with the engine already meeting tighter emissions mandates proposed for 2006. This environmentally friendly personality was no accident. During Sweden ’s long, cold winters, Volvo engineers burned the midnight oil. New design piston and combustion chamber squeeze the maximum BTUs out of every drop of diesel fuel. Obviously the turbocharger and charged air cooling are also part of the equation.
Charged air cooling simply means cooling the intake air. Cooler air is denser, and packed with a greater volume of oxygen molecules. So every time the engine takes a deep breathe there’s more oxygen available to light the fire and build more horsepower. You already knew a turbocharger converts waste exhaust heat into spinning motion. The motion rotates a pump that jams even more cold air into the engine. The net result of this one-two punch of charged air cooling and turbocharger is a long and flat torque curve. What that means to the helmsman is as simple as the sea is salt. There’s enough power to decisively maneuver a boat from idle all the way up through wide open throttle (WOT). Another plus, fuel economy is more than adequate. At 2000 rpm the engine sips a little more than one gallon per hour (gph). At WOT (3000 rpm) the volume increases to about 4.75 gph.
One item that impressed me was the stock alternator. It’s rated 115 amps. Usually cruisers have to throw away the standard item 50 -50 amp alternator and ante up several hundred dollars for a high output alternator capable of keeping house bank batteries charged to 80 percent of their capacity. For those boats where 115 amps isn’t enough. Even at idle the alternator makes more than 35-Amps and at cruising speed 100-Amps. Also, Volvo offers a 220 volt AC alternator rated 2.2 kW. This would be a wise option for anyone cruising tropical waters and desiring air conditioning and a deep freeze for tuna steaks.
As for reliability, you should also know Volvo subjected this new engine to a grueling battery of tests. If I know engineers, they were in tears at the thought of the things they had to do to their new creation. But for reliability sake prototype motors logged hundreds of hours and were abused beyond belief. Better a component part breaks down during testing than during a run down the Baja coast. A real eyebrow raiser: Volvo owners won’t have to change engine oil until 400 hours, or once a year, whichever comes first. Freshwater cooling is standard (exhaust manifold and turbocharger), with the exhaust elbow seawater cooled.
For cold weather starts, the engine is equipped with glow plugs. The standard instrument panel includes an alarm for monitoring engine temperature, oil pressure and alternator charge rate. Noteworthy options include a tachometer and engine hour meter. The deluxe panel includes a key switch, temperature gauge, oil pressure gauge, voltmeter and tachometer with engine hour meter.
Along with the new engine Volvo has also introduced a new version of its venerable sail drive. We saw the first incarnation of the sail drive back in 1973, the original renowned for low drag resistance. Personally, I like a sail drive for the way it eliminates aligning the propeller shaft to the engine and the need for repacking a chronically weeping stuffing box.
For more than 30 years the Swedes have been tweaking and tuning their creation, making the sail drive an even more potent force. A point of interest, all the yachts that sailed in the Volvo Ocean Race were fitted with Volvo sail drives This year the company introduces the 150 S –Drive. Coincidentally, it can now handle engine installations up to 75 horsepower. What pleased me most was the way the gear oil for the drive can be changed from inside the boat. Also, the sacrificial anode is split so that it can be removed and replaced without dismantling the propeller. Because the driveline can be rotated 180 degrees, the engine can be positioned at either fore or aft. For those applications where an S-drive is inappropriate, the D2-75 can be installed with any one of eight straight or down angled gearboxes. A variety of gear ratios are available. D2-75 can made even more efficient option with the addition of a new four-bladed folding propeller. Compared to conventional fixed propellers, folding propellers, produce substantially less drag under sail.
Finally, Volvo Penta also offers a tantalizing array of engine accessories. Most notable are the pulleys and universal brackets for power takeoff (PTO). PTO can be set up to run a hydraulic pump to run an anchor windlass or bow and stern thrusters. The company also offers hot water systems that plumb into the engine as well as the usually touch-up paint, engine oil and cleaners.
|Volvo Penta D2 -75||Specifications:|
|Displacement||134 cubic inches / 2.2 Liters|
|Power rating||75 horsepower @ 3000 rpm|
|Operating range||2700 to 3000 rpm|
|Block configuration||in-line four-cylinder|
|Weight (minus transmission)||529 pounds|
Author Timothy Banse has published articles in Popular Mechanics, All Chevy, Pickup Van & 4-Wheel Drive, Mecanica Popular, Motor Boating, Yachting, Mar y Vela and many other magazines and newspapers from around the world. He writes about cars, trucks and tow vehicles and marine-engine technology.