Volvo Penta  - 8.1Gi (375-hp)

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Captain's Report

Volvo Penta 8.1L

We’ve brought Volvo Penta to the test table with their 8.1L engine to see how it performs in a typical application. 


Volvo Penta 8.1L

You can see how Volvo has designed the 8.1L with a high exhaust manifold, the Catalytic converter is located in the top section.

The Test Engine

Volvo Penta puts out three different versions of the 8.1, the 375-hp 8.1Gi, the high output 420-hp 8.1GXi, and the now required (in America) catalyzed version, the 400-hp 8.1GiC.

The three models of the 8.1L all share common features of being electronically controlled, and equipped with EVC, which we’ll get into shortly, in addition to being fuel injected.

This engine is typically used in a single power application in boats roughly 24’ (7.32 m) to about 28’ or 29' (8.84 m) in length. For a twin engine application, you’d be looking at the 30’ (9.1 m) to 40’ (12.2 m) range.

Our test boat was powered by a pair of 375-hp 8.1L engines.

There are several things that are noteworthy when looking at the overall picture of this engine, including but not limited to...

• The fuel and oil filters are top mounted and easily accessible. The oil filter is a cartridge type that makes changing a breeze.

• The water pump is crank mounted and the impeller is changed with four screws (that are protected with O-rings to prevent dropping them into the bilge).

• The engine is computer controlled for improved performance and reliability. The ECM, or Electronic Control Module, is plugged into the engine with a single plug, albeit a lengthy one.

• No more crowbars to adjust tension of the alternator belt. It’s combined to the function of the externally mounted serpentine belt and runs through an auto tension adjust.

• An overheat sensor drops the performance into a reduced “get home” mode if you inadvertently suck a plastic bag into your intake.

• It is shipped with Platinum Iridium tipped spark plugs for improved performance and longer life.

Volvo Penta 8.1 L Engine Test Results

Over the years we have tested 11 boats powered by the 8.1 L Volvo Penta engine in both single-engine and twin-engine applications. Every boat turned in different speeds and fuel consumption figures that varied because of many factors. Most prominent among those are weight, beam and deadrise. Testing conditions also bear on the results.


Readers should view this data as a snapshot of the engine's performance in different conditions, and not necessarily precisely repeatable.  Nevertheless, by studying the data you will discover patterns and trends that should help giude you in your engine selection.


Below are the performance tables for three different boats all powered by a single 375-hp Volvo Penta 8.1 L Gi engine.  Note the description of the boats under each table will bear on performance.


Volvo Penta 8.1L

Test of a 28' (8.5 m) boat with a 8'6" (2.59 m) beam and an 18-degree deadrise that weighed 7,046 lbs. (3,201 kg.) wet, including crew and gear. It was equipped with a Duoprop F5 lower unit with a 1.78:1 gear.


Volvo Penta 8.1L

Test of a 26' (7.92 m) boat with a 9'4" (2.84 m) beam and an 18-degree deadrise that weighed 7,910 lbs. (3,595 kg.) wet, including crew and gear. It was equipped with a Duoprop F5 lower unit with a 1.78:1 gear.


Volvo Penta 8.1L

Test of a 28' (8.5 m) boat with an 8'6" (2.59 m) beam, a 24-degree deadrise and weighing 6,500 lbs. (2,954 kgs.) wet with crew and gear. It was equipped with a Duoprop F7 lower unit with a 1.78:1 gear.

At the top of this page is a tab that will take you to all of the boats we have tested with Volvo's 8.1 L engine. We invite you to view all of the results.


What is Volvo Penta Talking About?

One factor of these Volvo Penta gas engines that many find confusing, including us, is the nomenclature of each engine type. GI,GX, Gxi… etc. What does it mean? It’s really simple code, and as it turns out, it’s not a secret where if they tell you, Volvo Penta will have to put out a contract on you. Once you get the hang of it, you’ll realize it’s pretty straightforward. Write this down…

First off, they all start with G, like in Gas.

• GL – Low output. This is for lower end 4.3s at 190-hp. There are no “L” engines above 4.3.

• GX – X is for Extreme. Why not use E for Extreme??? We’ll get to that later. Generally an “X” engine has another 20-45 extra horses for an engine of the same size. The 8.1Gi is rated at 375-hp. The 8.1GXi is 420-hp.

• i – Fuel injected. No carburetor. For some reason it’s the only letter identifier that is in lower case and it’s good for the engine, but wreaks havoc on a spell check. The 8.1GXi is extreme hp and fuel injected.

• C – Engines with this designator will be equipped with a catalytic converter, just like in your car. This is a new requirement and any 8.1L engines manufactured after 12/09 will be required to be equipped with one. So why might your new boat not have one? Because manufacturers can still use up their supply of older non-catalyzed engines, which they’re trying desperately to do as this feature adds roughly $3,500, but it’s a federal requirement now so don’t yell at the builder.

• (E) – The engine is set up to accommodate EVC or Electronic Vessel Control. This is the coolest thing to come along since ice and we’ll get into it in greater detail later. You can also see our dedicated video on the benefits of EVC. For now, let’s just stick with the basics and also the fact that now we know why “E” doesn’t stand for Extreme.

So to sum it all up, an 8.1L GXiC(E) will be a 8.1Liter, Gas engine, Extreme hp, fuel injected, equipped with a Catalytic converter, and accommodate EVC. See, simple.

Volvo Penta 8.1L

When the cover comes off the top of the 8.1L engine a whole host of features are revealed. Let's go over them in detail.



EVC

We would be remiss if this article is we didn’t discuss the benefits of EVC, and after testing the systems functions, we can honestly declare that it’s the greatest technological leap forward since they started slicing bread, and it’s a feature that is directly felt and experienced by the operator.

The acronym stands for Electronic Vessel Control and it’s the latest development in engine control and instrumentation, and you can take it from someone who has tested EVC personally. Once you’ve experienced it, you never want to go back.

Because this isn’t a full blown EVC article, the short version is that EVC allows for plug and play installation between the motor, and both the engine controls and helm gauges, that allows you to not only control the flow of data to the helm but electronically control the engines, and therefore the output and synchronization with effortless authority.

That means that all those mechanical connections between the helm and the engine are long gone, and adding a remote location for your engine controls, say at the stern or for wing controls, is as easy as adding another wiring run. And the digital controls are opening up a whole new breed of capability. Cruise modes, tow modes, trim assist, and single lever modes… all are available at the push of a button.

In summary, we found the test boat handled extremely smoothly to power inputs. Acceleration was crisp with no hesitation upon rapid advancement of the throttle. In high power turns there was no ventilation of the props. Point of fact, the only thing that made this application better was the addition of a second 8.1L.