Volvo Penta's 5.0 GXi - 06/03/2009
BoatTEST.com has tested 20 boats with both single and twin Volvo Penta 5.0 GXi power and the performance results are remarkably consistent in class among the boats we checked. With 5.0 liter displacement and eight cylinders, this Volvo Penta engine delivers over 250-ft. lbs. of torque at 1000 rpm up to 302-ft. lbs. at 4000 rpm. This relatively flat and powerful torque curve makes the engine ideal for waterski and wakeboard activities by delivering relatively constant torque throughout the useful rpm range.

Volvo Penta 5.0 GXi
The is about the way the 5.0 L engine looks when it arrives at the Volvo Penta plant for marinization.


The 5.0 L engine is marinized in the U.S. by Volvo Penta, a Swedish company, which buys the blocks from General Motors’ Vortec division which manufacturers in Toluca, Mexico. Virtually every year the engine is refined or improved in some way by either Volvo Penta, Vortec or both. Some of the major improvements the last several years include its harden exhaust valve seats, hydraulic roller valve lifters and a new injector design that improves fuel injection reliability. The high-flow cylinder head with straighter intake ports and higher compression ration (9.4:1) delivers impressive horsepower.

Of the 20 tests conducted by BoatTEST, we looked at six, three 22’ boats with single 5.0 GXi engines with the SX drive unit (single prop), and three with twin installations in the 27’ to 30’ range.

22’ Sportboat Performance

We looked at tests of the Glastron 225 GT, Rinker 212, and Azure 211. The Glastron and Rinker weighted 3000 lbs. and 3120 lbs., respectively, and the Azure was 3900 lbs. The WOT speeds for the three boats were remarkable close: 52.3, 51.7, and 49.8 mph, respectively. But at best cruise speed, the three boats ranked in reverse order. With the flattest dead rise at 16-degrees, the Azure had the highest best cruise speed at 31.2 mph. Then came the Rinker at 27.3 mph, followed by the Glastron at 26.9.

 

Roller Valve Lifters
A 5.0L Vortec improvement: Roller valve lifters reduce friction and improve performance.

All three boats got terrific fuel efficiency with the Rinker first with 4.62 mpg, Glastron at 4.52 mpg and the Azure at 4.18 mpg. With this kind of mileage all three boats have good range for a sportboat and fuel costs are a small part of the annual budget.

The Glastron 225 GT had the fastest hole shot at 3.0 seconds, but the slowest was only .4 behind.

27’- 30’ Express Cruiser Performance

Among the larger boats, the Formula 27 PC was the lightest at 9500 lbs., and the Regal 3060 the heaviest at 10,500 lbs. The Monterey 282 split the difference at 10,099 lbs., and also had the lowest dead rise at 16-degrees. All three boats were equipped with Volvo Penta’s Duo Prop lower units. Interestingly the fastest of the three was also the heaviest – the Regal 3060 which recorded at WOT of 47.7 mph with an 18-degree dead rise. Next came the Monterey at 47.0 mph and the Formula at 46.2 mph.


GM Vortec
When GM’s Vortec modified the engine to run on liquid propane and natural gas, marine customers received a benefit as well. The resulting high-flow cylinder head, with straighter intake ports combined with a higher compression ratio, delivered significantly better combustion for gasoline as well.

 

At best cruising speed, the Regal 3060 once again was the fastest at 25.8 mph, followed by the Formula 27 PC at 23.1 mph and the Monterey at 20.7. Formula had the best mpg numbers at best cruise at 1.84 mpg, followed by the Regal with 1.73 mpg and the Monterey at 1.62 mpg. As we said, the boats were surprisingly close. The Monterey had the fastest hole shot at 6.7 seconds to plane.

Relationships

By this time we suspect you’ve noticed a rather interesting weight/horsepower/speed relationship. Essentially, the express cruisers weigh three times more than the 22’ sportboat boats, yet go almost as fast with twice the horsepower. The three sportboats got an average of 4.44 miles per gallon at best cruise and the three express cruisers averaged 1.73 mpg. Shouldn’t they have gotten half what the single engines got? That’s not quite how things work with boats, particularly when the larger boats are three times heavier.

But evening up the challenge for the larger boats was the fact that all three were equipped with Volvo Penta’s Duo Prop lower units which are on the order of 30% more efficient than the conventional single-prop stern drive. This is an important factor in accounting for the relatively high speed of the express cruisers given their weight, and also fuel mileage.

Reliable power properly matched to your application is the key to boating fun. Most boat builders offer a choice of stern drive engines, so before you buy you do your homework. Engines are expensive, so make sure you are getting the right engine for the job.

To find out more about the Volvo Penta 5.0 L GXi…

To see BoatTEST.com tests of 20 boats powered by the Volvo Penta 5.0 L GXi…


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