Mercury 400XXXL 400HP – Verado V10 35″ Shaft DTS Electric Start in Black

Mercury 400XXXL Verado 400HP V10 Ultra-Long

The Mercury 400XXXL Verado pairs a naturally aspirated 5.7L V10 with a 35-inch ultra-long shaft, built for the tallest transoms where a standard long-shaft motor would lose grip. At 695 lbs, this DOHC powerhead is part of Mulmarine’s outboard propulsion lineup for large multi-engine center consoles and walkarounds that need serious displacement-driven torque.

Peak output runs between 5800-6400 RPM, backed by a 150-Amp alternator that’s among the strongest in its class. The 2.08:1 gear ratio holds that 5.7L torque curve steady on extreme hulls. Built in the USA, this engine pairs SmartCraft Digital Throttle & Shift (DTS) with integrated electro-hydraulic power steering for control across deep ocean swells.

Technical Specifications of Mercury 400XXXL Verado

Extreme 35-Inch Shaft Authority

The 35-inch ultra-long shaft is the defining feature here, built for transom heights where a standard long-shaft motor would ventilate. That length keeps the prop biting on the largest deep-V hulls, holding forward thrust through massive ocean swells during long-range transits.

Naturally Aspirated V10 Displacement

The 5.7L V10 skips forced induction in favor of raw displacement, which is why the power delivery stays smooth and predictable rather than peaky. That approach favors durability and steady low-end torque for hauling heavy fuel loads offshore.

150A High-Output Charging

A 150-Amp alternator generating 1890 Watts covers the electrical load of modern offshore rigs — radar, gyrostabilizers, and multiple large navigation screens can all run simultaneously without draining the house batteries during long trips.

Mercury 3-Year Protection

Every Mercury 400HP Verado V10 carries a 3-year limited factory warranty, with genuine parts available through Mercury’s nationwide dealer network for long-term support.

Maintenance & Longevity

Keeping the 8.0L wet sump lubrication system topped off with clean oil protects engine tolerances over time, and the cooling system needs a fresh-water flush after every saltwater run. Pro Tip from the Shop: on 35-inch shaft engines running as part of a quad-engine setup, keep an eye on the NMEA Gateway for system-wide diagnostics and grease the steering tube regularly — both take a beating in that configuration.