First drive: 400hp Mercury V10 Verado

In the mid-1990s Mercury released Project X, an all-new small-displacement supercharged six-cylinder engine that would revolutionise performance boating.

However, as time has progressed, Mercury has come to realise that an engine’s displacement, not artificially stuffing air and fuel into its cylinders, is better suited to pushing new generations of ever-larger boats.

Mercury’s 3.4-litre V6, newer 4.6-litre V8 and even newer 7.6-litre V12 – all big displacement, long-stroke engines – were a sign that the 350hp and 400hp versions of the 2.6-litre huffed short-stroke in-line six’s days were numbered.

Which leads us to Project Tarpon, an all-new 5.7-litre V10 engine that extends from the V6 and V8 engine family, and borrows bits of the V12 to enhance its performance.

The engine is available in two states of tune, a 350hp entry-level version and the one we’re testing here, a 400hp version.

Both add the “Verado” name to their monikers, meaning they’re considered part of the more premium performance-oriented end of the Mercury outboard engine family.

We’ve discussed earlier how because Mercury builds its own clean-sheet engines and doesn’t borrow from an existing car-based platform, it can build the engines it wants.

The brief for this engine was to match or better the spread of torque than the forced-induction six-cylinder unit it was to replace. The only way to do that was to move to an all-new cylinder count that added the displacement Mercury needed to hit that goal.

The new V10 is built on the same production line at Mercury’s US factory as its V6 and V8 engines and features the same narrow 64-degree bank angle that makes it a fairly compact package to hang off the transom of a boat. Each bank has 20 valves, meaning the engine has 40 in total.

A big change with this generation of engines was the need to get all that torque into the water. To achieve this, Mercury had to completely rethink the lower unit, creating one with a much larger diameter torpedo and an equally large propeller with some of the largest blades Mercury has produced. More blade area equals more bite on the water, which in turn means better holeshot performance and acceleration. To achieve this, Mercury had to reduce the V10 Verado’s gear ratio to 2.08:1.

The engine uses the same mounting bracket as the V8 but is mounted around 2.5cm higher on the transom because it sits taller overall. The engine’s “advanced midsection”, known as AMS, includes rubber mounts that are designed to twist and put more rubber in contact with the engine cradle, smoothing out vibration.  

Mercury has future-proofed the new V10 Verado for a new generation of energy-independent boats that will use banks of lithium-ion batteries to replace gensets. Plans are afoot to add a switchable 12/48-volt alternator that will produce around 6500kW of battery-bankable electricity per engine, and power a new generation of 48-volt acessories.

Plans also include adding Mercury’s own electric-assist power steering to the engine sometime next year to allow it to fully integrate with the boat’s electronics.

Of note, this engine tips the scales at just 315kg, a big competitive advantage over similarly powered rivals competing for transom space. On a triple-engine install, this weight advantage can make as much difference as adding a fourth V10 Verado and still having kilos to spare.

There’s no telltale with the 400hp Mercury V10 Verado, with skippers instead having to rely on the engine’s connectivity with digital multifunction touchscreens to show that the engines are operating in their happy zone. The decision to eliminate it was twofold – first, it added significantly to the noise of the engine when it was idling, and second, to date, no one has asked for their 600hp V12 Verado to be fitted with a telltale.

The first of these new-gen V10 engines are due to arrive in Australia in around April next year, which means our first close look at it on local shores is likely to be the 2023 Sanctuary Cove International Boat Show.

Of note, the engine will come with a 12-volt alternator that produces an impressive 90 amps at idle, 90 amps when coming up to speed and 150 at running speeds, meaning it can recharge a decent bank of batteries and run a fair amount of electronics.

As for pricing? Mercury says the V10 is likely to be slightly more expensive than the six-cylinder engine it is replacing – it is a whole lot more metal for starters – but because the technology on it is much simpler than used for the supercharged six-pot, it shouldn’t be that much more expensive.

Integration, particularly with Simrad electronics, means that you don’t need to worry about using separate VesselView readouts to monitor the health and performance of your 400hp Mercury V10 Verado.

One place where the owner experience should vastly improve is when it comes to servicing the 400hp Mercury Verado V10. You don’t need to pull the engine cowl off to check or add oil, and all the lower drive service points are located in behind the propeller, so there’s no need to remove the chaps.

Finding out exactly what the differences are between the 350hp and 400hp versions of the Mercury V10 Verado proved difficult, with no one we spoke with at Mercury willing to go into details. However, it is larger than the inline six-cylinder engine it replaces, and only taller because the alternator sits on top of the V10.

Of note, this engine is designed to produce 400hp at the prop on 91RON fuel. None of the fancy stuff for us. 

Mercury gave boatsales.com.au an opportunity to test the new Mercury V10 400hp Verado at a special launch event at Lake X, the engine maker’s top-secret proving ground in Florida. Finding Australian analogues among the range of Brunswick Group boats available on the day was a bit difficult, so for this test we settled on an 8.2-metre SeaVee 270z fibreglass bay boat and a 6.4-metre Lund 2175 Pro-V, an alloy bass tournament boat, as our rides for the day. Both were fitted with the 400hp Mercury V10 Verado.

If you love your engines, you’ll be smitten with this one from the first time you start it up. Engineers have built a wonderful-sounding throttle blip into the ignition process so that it starts with a nice V10 snarl.

Let’s jump onboard the SeaVee first. This is a boat that can take either twin 225hp engines, or a single ranging from 350 to 450hp. Fully loaded, it weighs around 3100kg, so it’s a substantial mass for our single 400hp Mercury V10 Verado to push around.

Beneath it is a shallow-draft twin-stepped hull with a relatively shallow, skiff-like 17-degree variable deadrise.

It doesn’t take much effort to get the SeaVee up onto the plane. A quick roll of the throttle lever and the boat quickly pops up onto the plane. Once there, even small throttle adjustments via the fly-by-wire controls are immediate and direct.

At 4600rpm, we’re cruising comfortably at 31.0 knots and using around 15.1 gallons an hour. Winding up to WOT, we’re hitting more than 40 knots as the SeaVee hull skims across the water’s surface.

Mercury says that the V10 is likely to use more fuel than the six-cylinder engine it will one day replace, but says it will be a marginal increase, and maybe even a bit of improvement, at certain parts of the rev range.

We had a bit more time at the helm of the Lund, so potentially have a slightly better feel for the 400hp Mercury Verado V10’s performance. However, even though the Lund is a pressed alloy boat, it didn’t really feel like one.

That’s because it carries more than a tonne of baggage, and that’s before you add an engine, fuel, fishing gear and people. The weight, coming largely from the hull’s solid internal fit-out that enhances its brief as a tournament boat, means it rides and handles more like a fibreglass boat than a pressed-metal tinnie.

Still, the performance is impressive. The Lund features a set of analogue gauges below dual Lowrance HDS multifunction screens, and the speedo’s dial is nudging 55mph as we blast along the flat surface of Lake X at a conservative 5600rpm – yep, but for a bit of wake washing across the water we could probably push it above 60mph.

We stop and try a couple of holeshots. Pounce on the throttle and the 400hp Mercury V10 Verado tucks in slightly as the prop bites and turns revs into acceleration. The G-forces this engine is able to generate as the hull leaps forward makes it hard to film the process.

The engine is equally impressive as it carves into a turn. Mercury has fitted the 400hp V10 Verado with automatic trim, so the engine will automatically change its angle of attack to optimise its operation. The engine will even step up its revs slightly mid-turn to hold a constant speed – something we’ve likely only seen before as a feature on high-end ski boats.

What’s quite notable about this engine is how quiet it is at any speed. Holeshots are performed without the cacophony of induction whistle and exhaust roar and, at speed, it’s the wind coming over the Lund’s low wrap-around windscreen that’s making conversation difficult, not the powerplant working hard behind us.

There is an exhaust bypass that will replace the V10’s gentle whisper with a more primal burble, but it’s a deep dive into the multifunction screen’s menus to find the electronic switch that opens it.

The 400hp Mercury V10 Verado is a gift that keeps on giving. Strong at any part of the rev range, it’s going to be a formidable addition to the transom of the boats fortunate enough to wear it.

Once again, Mercury has shown that going alone and designing its own boat engines from the ground up can yield huge benefits for owners once they hit the water.

What’s next? We reckon Mercury Racing’s 450hp version of the 2.6-litre supercharged inline six-cylinder is the next one lining up in the crosshairs. Will it be an atmo V10 that replaces it? If Mercury is sandbagging with the 400hp version, chances are it will be.

Specifications
Model: 400hp Mercury V10 Verado
Pricing: TBA, but will be more expensive than the current in-line six-cylinder 350hp engine
Engine type: Four-stroke dual overhead cam, 40-valve
Cylinders: V10, 64-degree bank
Fuel management: EFI
Weight: 316kg (lightest model)/328kg (heaviest model)
Displacement: 7554cc
Bore x stroke: 92mm x 86mm
Maximum output: 350hp @ 5800rpm
Operating range: 5800rpm – 6400rpm
Shaft length: 508mm (20-inch), 635mm (25-inch), 762mm (30-inch), 889mm (35-inch)
Alternator: 12V/150A, 48V/150A (opt)
Trim method: Power trim/tilt
Gear ratio: 2.08:1 (RH/LH)
Recommended fuel: Regular unleaded
Oil capacity: 9.5L (with filter)
Counter-rotating: Available
Servicing: Annually (or every 100 hours after first service)
Emissions rating: CARB 3-star/OEDA 3-star
Warranty: 3+3 years/3-year corrosion