Mercury – SpitFire X7 4-Blade Stainless Steel Propeller | 12.8" Diameter x 21" Pitch | Right-Hand Rotation | 4-Blade | Stainless Steel | Polished Finish | 8M0151364

Overview

When you’re chasing open water speed and precision handling, few props make your boat feel as alive as the Mercury SpitFire X7 12.8x21 Right-Hand 4-Blade Stainless Steel Propeller (8M0151364). From the moment you throttle up, you can feel it crisp acceleration, confident grip, and a smooth transition from idle to plane. It’s fast, responsive, and tuned for boaters who want to feel every ounce of performance their outboard can deliver.

This prop isn’t just about getting there first it’s about how it feels along the way. The SpitFire X7 turns raw power into fluid motion, offering steady lift and tight cornering without the slip or drag that slows others down. If you love running clean lines and feeling that precise control under your fingertips, this prop delivers every time.

Key Features

• Diameter and Pitch: 12.8" Diameter x 21" Pitch
• Rotation: Right-Hand Rotation
• Blade Count: 4-Blade Design
• Material: Mercury X7 Stainless Steel Alloy (30% stronger and four times more durable than standard stainless)
• Finish: Polished Stainless Steel
• Hub System: Requires a Mercury hub kit (sold separately)
• Design Details: Compact diameter and aggressive blade geometry designed for exceptional acceleration, grip, and top-end speed; includes Performance Vent System (PVS) for customizable hole shot tuning

Engine & Boat Compatibility.

• Works with Mercury and Mariner 40–60 HP Command Thrust Outboards (4.25-inch gearcase)
• Fits Mercury 75–125 HP TwoStroke and FourStroke Outboards
• Ideal for midsize boats, performance runabouts, and fishing rigs where quick acceleration and high-speed stability matter
• Suitable for both freshwater and saltwater applications

Performance Benefits.

The SpitFire X7 12.8x21 is all about turning power into precision. Its smaller diameter and four-blade configuration give it incredible bite, letting your boat leap onto plane with purpose and confidence. Once you’re up, you’ll notice how it holds speed effortlessly, tracking straight and true even in choppy water. The aggressive blade design grips hard in turns, delivering predictable handling whether you’re cruising light or carrying a full load.

At higher speeds, this prop keeps things smooth and steady—no chatter, no vibration—just clean, controlled movement through the water. Mercury’s X7 alloy brings both muscle and resilience, flexing less under torque and resisting damage where others would give in. And with the Performance Vent System (PVS), you get to fine-tune how your boat accelerates by adjusting venting for your exact setup. It’s like personalizing your throttle response for the way you run.

Why is this prop a strong choice vs. alternatives?

• Mercury OEM Quality: Designed, engineered, and tested by Mercury for optimal performance and perfect fit.
• Performance You Can Feel: Quick acceleration, confident grip, and steady lift make it ideal for performance-minded boaters.
• Durability That Lasts: X7 stainless steel is 30% stronger and four times more durable than conventional stainless, resisting flex and corrosion.
• Tunable Acceleration: The PVS system lets you tailor hole shot performance to your load and conditions.
• Versatile Application: Perfect for midsize Mercury outboards across a wide range of boats, from sport rigs to fishing setups.

FAQ Section

Q1: Which Mercury engines does the SpitFire X7 fit?

It fits Mercury and Mariner 40–60 HP Command Thrust outboards with the 4.25-inch gearcase, as well as Mercury 75–125 HP TwoStroke and FourStroke outboards.

Q2: What makes this propeller different from other Mercury options?

The SpitFire X7 uses an exclusive X7 stainless steel alloy and a four-blade design that combines aggressive acceleration with top-end stability, outperforming most stainless props in its class.

Q3: How do I know if this pitch or size is right for my boat?

If you’re looking to lower your engine RPMs slightly at wide-open throttle or maximize top-end control and lift, the 21-pitch SpitFire X7 is an excellent match. Always verify your engine’s recommended RPM range.

Q4: Can this prop be used in both saltwater and freshwater?

Yes. The polished stainless finish and corrosion-resistant X7 alloy make it a dependable performer in any environment.

Q5: What hub system does it use?

It requires a Mercury hub kit (sold separately) for secure installation, smooth shifting, and vibration-free performance.