Mercury Verado 350 and 400R outboards: full analysis

Ever since Mercury Marine launched its six-cylinder Verado range in 2004, no other four-stroke outboard motor range has come close to these outboards for holeshot, midrange fuel efficiency, top end performance and inherent engine balance. And boaters must agree as 75,000 units of the Verado L6 models have been sold worldwide since 2004.

Thanks to Mercury Marine, I got to review these outboard engines at the 2015 Miami International Boat Show. The Mercury 350 Verado engines I reviewed were fitted on a range of hulls, ranging from a single Verado 350 on a 7.6m Ranger 2510 centre console flats boat to quad Verado 400Rs on a 12.8m Marine Technology centre-console. All the outboard engines engines were evaluated for performance, operating ease, fuel efficiency and noise levels from enclosed waterways to offshore.

MERCURY VERADO 350

Unlike their less powerful counterparts, the Verado 350 and Mercury Racing 400R have a watercooled supercharger with a cleverly designed fresh air intake and vented flywheel cover, plus a charge air cooler. The ‘Advanced Mid-Section’ or AMS positions perimeter engine mountings around the engine pan to prevent any ‘rocking’ motion as the rpm increases or decreases.

The long bolt powerhead design eliminates the need for cylinder head bolt tensioning after the outboard motor leaves the factory, while roller cam followers mean periodical valve clearance adjustment is never needed.

Both Mercury engines have a 70amp belt driven (easy to service) voltage regulated alternator that automatically increases the idle from 600rpm to 725rpm should the battery charge drop below 12 volts.

The 2.6 litre engine has 24 valves operated by chain-driven double overhead camshafts and is cast from a mixture of extremely low copper-content alloys including magnesium.

Power steering is standard with Joystick Piloting optional on multi-engine rigs. This includes accurate boat positioning by splaying outboards independent of each other, while ‘Skyhook’ holds the boat in one position using GPS location fixing.

Having as little as 660mm centres between engines, the Verado 350 and 400R suit multiple engine installations way better than V-block engines. Trimming the engines is by the normal gearshift lever knobs, though twins and triples can be synchronised and controlled using just one lever.

VERADO 350 PERFORMANCE

Designed more for heavy duty rigs, the Mercury 350 Verado has its rpm limiter set at 6500. It has an integrated oil cooler mounted on the powerhead and well away from the oil sump and will run on premium 95 RON unleaded where 98 RON is not available.

There are four cooling water intakes at the gearcase torpedo nose in addition to the normal inlets above the torpedo. The gears and bearing carriers have been considerably strengthened over the previous 350 model.

I reviewed three configurations of the Verado 350, from single to triple installations. Though a tight engine reviewing schedule prevented acceleration tests, all the outboard motors had the brilliant holeshot and the excellent midrange fuel efficiency that comes from running a relatively small displacement powerhead on low boost up to 4000rpm.

No naturally-aspirated four stroke outboard ofcomparable output can do that, simply because a much larger displacement engine will always use more fuel at midrange rpm. Only at or near WOT does a naturally aspirated engine become more fuel efficient – but how many boaters run their engines at WOT offshore?

Twin Verado 350 engines + Mako 284 centre console. Despite having only 2.6 litres, twin Mercury 350s on a Mako 284 centre console (above) showed their bottom end torque by being able to plane and cruise on one engine at 26kts and 4500rpm. When using the Joystick control knob the engines splayed outwards to provide instant docking control.

Triple Verado 350 outboards + Boston Whaler 370 Outrage. Using the same system with triple Verado 350s on a Boston Whaler 370 Outrage, depending on which way the hull was spun, two engines turned to starboard while the third angled to port, or vice versa. The result was instant control without needing a bow thruster. The triple engines ran two right hand prop engines (centre and starboard) and one left hand prop engine (port).

MERCURY VERADO 350 SEA TRIALS

Single Mercury Verado 350 on Ranger 2510, with 19in pitch Quicksilver Bravo stainless steel prop; total displacement 2 tonnes.

* Data supplied by author. Maximum fuel efficiency was returned at 4000rpm.

All the 350 Verado engines tested had noise levels no greater when idling than a four-stroke Mercury 90 outboard, while at WOT they were actually quieter! Indeed, there’s no problem talking normally with these engines on the transom!

MERCURY RACING 400R

Being able to achieve 400 brake horsepower from a 2.6 litre outboard engine is simply amazing! A naturally-aspirated engine of this displacement would only develop around 150bhp, but by increasing supercharger boost a mere six per cent the Mercury 400 is in business, with its rpm limiter set at 7500. Don't try running this Mercury Racing engine on anything less than 98 RON unleaded.

The main engineering differences of the Mercury 400 over the Verado 350 are the Sportmaster gearcase with forward-angled leading edge and cooling water intakes under the torpedo nose in addition to the normal intakes above the torpedo, plus an engine oil cooler inside the sump. This functions as a heat exchanger system by passing water through cooling fins, just like a car radiator.

Mercury 400 quad rig. I reviewed the Mercury 400 only on a quad rig. In this configuration the 400Rs had the same noise levels idling as the Mercury Verado 350 and were just one decibel noisier at WOT, on par with a four-stroke Mercury 90 outboard. This is despite running a camshaft drive chain that's always noisier than a belt drive. Despite the closely-spaced engines, through tight turns at 5000rpm there was absolutely no prop blow out or ventilation

Running four Mercury 400 outboards meant that Joystick control was unnecessary, with the two starboard engines having right hand props and the two port engines left handers. So with the centre engines idling, the normal one ahead/one astern docking technique on the far starboard and port engines could be used – albeit not quite as effective as the Joystick control on the triple Mercury 350 engines.

MERCURY 400 OUTBOARD SEA TRIALS

Four Mercury 400 engines on a Marine Technology centre console, with 23in pitch four-bladed stainless steel props; total displacement 9 tonnes.

* Fuel data is total consumption across all four engines. Data supplied by author. Maximum fuel efficiency was returned at 4000rpm.

THE TRADE-A-BOAT VERDICT

Both the Mercury Verado 350 and the Mercury 400 Racing outboard engines show what can be achieved with a relatively small displacement powerhead. They are throttle responsive and fuel efficient but oh so quiet, and with their almost total lack of vibration they certainly won't reduce body flab.

MERCURY VERADO 350 AND 400R SPECIFICATIONS

TYPE Six-cylinder, petrol, supercharged four-stroke outboard motors

RATED HP 350, at 6100rpm; 400, at 6700rpm

REC. RPM RANGE, VERADO 350: 5800 to 6400rpm

REC. RPM RANGE, RACING 400R: 6400 to 7000rpm

WEIGHT Long – 303kg dry; X Long – 309kg dry; XX Long – 315kg dry

GEAR RATIO 1.75:1 for both

MERCURY VERADO 350 PRICE $POA

OEDA 2 stars for both

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