The Volvo Penta 350-hp small block V8 has a wide range of applications because of it light weight (996 lbs.) in both single and twin-engine installations. While there is nothing new about variable valve timing, there is something new about the low-end torque and noteworthy fuel efficiency that we experienced during our tests recently. The block comes from GM and has proven itself in all manner of small truck and SUV applications. Volvo has marinized this basic block with some clever innovations which make the package more user friendly and more durable in the marine environment.
Volvo Penta V8-350 Captain's Report
Volvo Penta’s new small block V8 engine for sterndrives was recently announced. This high-tech engine produces 350 ultra-clean horses from its catalyzed mill, and is available with electronic controls. With the entirely new 5.3L V-8 platform, the package is completed by Volvo Penta using its own engine management unit and accessories systems.
This powerplant is engineered with an all-aluminum block and heads, direct fuel-injection and variable valve timing (VVT). The in-cylinder fuel-injection allows for increased compression ratios, while the VVT improves torque and greatly reduces emissions. The result is an engine that has impressive torque throughout the low, mid, and upper rpm range.
Volvo Penta Marinization
Virtually everything on the basic block has been designed and assembled by Volvo Penta. Volvo Penta draws on its decades of experience in the boating industry to equip the engine to serve the unique requirements of sterndrive boats that make special demands on a propulsion system.
Its proprietary accessories and engine management systems, their materials, design and placement, make the total 996-lb. (452 kg) package both reliable and easy to use by the boat owner. Most notable on this engine is the Volvo Penta Front Engine Accessory Drive (FEAD) system. See more on this below.
Our Formula 260 SS test boat proved to be an enjoyable test bed for the 5.3L V8.
The V8 was tested on a Formula 260 SS bowrider that measured 28’6” (8.69 m) overall with an 8’6” (2.59 m) beam. We loaded it with two people, some test gear and 69 gallons (261 L) of fuel for a total test weight of 6,911 lbs. (3,135 kg). At the stern, a Volvo Penta Duoprop sterndrive was attached running a final drive reduction ratio of 2.14:1 and spinning a pair of stainless steel FH5 props front and rear.
Our performance curve for the 350-hp V8 fitted in a Formula 260 SS model.
High Torque. Despite the heft of our test rig, the 5.3 supplied a spirited attitude to the boat. The torque of the engine can be felt as soon as the throttle is cracked and continues to have a strong pull all the way to WOT.
Speeds. The power band is smooth and virtually instantaneous as we averaged 4.1 seconds to get the big bowrider on plane. Getting to a calculated cruise speed of 22.4 mph at 3000 rpm took around 6 seconds for an economy of 3.15 mpg. From 4000 rpm to WOT (5500 rpm), the engine’s horsepower takes over from the torque output to propel the boat to a top speed of 52.3 mph.
PTA (Power Trim Assist). Our test boat was equipped with EVC, which includes PTA as one of the features. This snazzy feature will automatically trim the vessel to optimize its running attitude.
Nestled inside our Formula, the V8-350 weighs only 996 lbs. (452 kg).
Motor Mounts. Volvo Penta uses elastomeric motor mounts that are designed to take the tremendous torque and g-forces that occur in this application. The name of the game is to keep the 996-lb. (452 kg) power plant in place and perfectly aligned even if the boat is catching air and slamming down on a hull bottom.
This chart shows our test numbers from the 350-hp V8.
Block and Heads
The 323 cu. in. motor can spin to 5800 rpm with cylinders that measure 3.92” by 3.62” (.099 m by .092 m) for bore and stroke. Six-bolt, powdered metal main caps fasten the crankshaft and are surrounded by a structural aluminum oil pan. Volvo Penta engineers designed the motor for salt-water service, so closed-loop cooling is standard. Exhaust manifolds are raw-water cooled.
The engine’s aluminum cylinder heads feature stainless steel valves that are controlled by a hydraulic cam phaser. The valve train is manipulated electronically via the ECU in order to change the intake and exhaust valve’s timing and duration. This allows optimization of the combustion process and maximizes output while minimizing emission.
Fresh water engine flush is located at the front of the engine, next to the engine oil dipstick.
The closed-loop cooling system incorporates an easy to service heat exchanger.
This externally mounted raw water pump is easily accessible for servicing.
Intake and Exhaust
The V8’s sophisticated in-cylinder fuel-injection uses a common rail delivery system fed by a high-pressure mechanical fuel pump located on top of the engine. It precisely aims 2,250 PSI atomized fuel into the combustion chamber and is compressed by 11.0:1 ratio pistons.
Inside the aluminum exhaust manifold shown here, is the catalytic converter and twin oxygen sensors. Pre catalyst wide band oxygen sensors are mounted in each exhaust manifold. They work in harmony to control the air-fuel mixture, allowing this engine to easily meet EPA, CARB and EU RCD emission regulations.
The engine computer is Volvo Penta’s fourth generation (4G) Electronic Control Module (ECM), and it provides engine protection protocols should a failure occur, plus full diagnostics support. The ignition system uses long-life iridium tipped spark plugs that are powered by eight separate ignition coils, reducing maintenance costs and frequency.
The optional versioned engine includes Electronic Vessel Control (EVC) for a modern, all digital engine and drive control. The EVC features include joystick driving, autopilot, joystick docking, cruise control, low speed mode, PTA (Power Trim Assistant), single lever mode, sportfish mode, tow mode, and trip computer. EVC places all of these functions together so that the driver can easily have control.
FEAD Innovation Reduces Maintenance
To improve reliability and maintenance, Volvo Penta developed FEAD (Front Engine Accessory Drive). This specially designed housing bolts to the front of the engine and supplies all the plumbing and mounting locations for the engine’s accessories.
As a result, hoses, hose clamps and other equipment that are prone to degradation over time are reduced. It also incorporates the engine’s oil filter housing. This eliminates leaking cooling hoses, broken clamp issues and significantly reduces associated hardware.
This bench top view shows the complexity of the FEAD manifold. (Note the replacement oil filter element to the left.)
For maximum performance, the V8 should be mated with the twin-wheeled Duoprop drive shown here, the drive is available in 1.95:1, 2.14:1, and 2.32:1 ratios.
Volvo Penta recommends the Duoprop set-up. Board sport customers can option for the new Forward Drive (FWD) propulsion system that can be had in 1.95:1, 2.14:1, and 2.32:1 ratios. All Volvo Penta drives use a cone clutch and pattern-matched spiral bevel gears. They also incorporate a kick-up function should an object be struck while underway.
To help protect your investment, Volvo Penta warrants engine packages registered in North America for five years of factory protection. The warranty is factory-backed and administered, using no third-party companies. Engine packages for internationally registered engine packages are warranted for two years, with an additional three years of protection for major components.
To See Volvo Penta's microsite and explanation of the new generation small block V8 engines... click here.