Mercury introduces new V-8 outboards

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The engines mount on 26” centers to facilitate multi-motor installations. 

The engines mount on 26” centers to facilitate multi-motor installations. 

After introducing naturally aspirated V-6 outboards at the Progressive Miami International Boat Show in February, Mercury Marine today is pulling the sheet off new V-8 outboards that are also not supercharged.

 Depending on the model series, the new motors will be available in horsepower ratings ranging from 225 to 300 hp. The 4.6L V8 AMS Verado and 4.6L CMS FourStroke will come in 250 hp and 300 hp ratings. The 4.6L V8 CMS and Pro XS come in 200-, 225-, 250-, and 300-hp versions. For commercial applications, the 4.6L V8 AMS is only available in 300 hp and the CMS SeaPro can be had in 225-, 250-, and 300-hp versions. Also new is the 3.4L V6 CMS Pro XS 175.

The most powerful of the new V-8s is a 300-hp model available in a variety of configurations.

The most powerful of the new V-8s is a 300-hp model available in a variety of configurations.

 The AMS and CMS designations stand for advanced midsection and conventional midsection family. The conventional midsection models are aimed at tournament anglers and performance-minded consumers for whom top speed and acceleration are key. The advanced midsection motors are targeted at more luxury-minded boaters who want increased noise and vibration mitigation. The new motors will use the same mounting brackets and systems as the V6s.

 One of the most noteworthy specifications of the new motors is that the FourStroke version weighs 527 pounds, the ProXS checks in at 505 pounds and the Verados weigh 600 pounds. That gives the motors some advantageous power-to-weight ratios.

 “Early on in the program, we set very lofty targets for weight on all of the new V6 and V8 variants and to hit these targets, every component had to meet a stringent weight target of its own,” said Mercury Marine president John Pfeifer in an email. “Everything from lightweight cowling materials to our proprietary alloys contributed to the achievement of these aggressive targets.”


Pfeiffer said that the motors’ 4.6-liter displacement is the highest in the 250 to 300-hp class, which should translate into some strong torque, especially at mid-range. There’s no replacement for displacement and having two extra cylinders compared to the competition is going to give Mercury some strong bottom-end and holeshot numbers.

Mercury claims the CMS engines are the lightest in their respective classes. All the engines use Advanced Range Optimization that automatically adjusts fuel delivery to deliver maximum range. Pro XS and Verado models have Transient Spark to boost torque during hole shot. Additionally, the Pro XS and Verados can be rigged with digital or mechanical components to make them more compatible for repower applications.

Adaptive speed control allows for engine rpm to be maintained regardless of changes in load or condition without needing to make frequent throttle adjustments. Verado V8 AMS models are the only ones in the new series compatible with Mercury joysticks.

As we saw on the V-6s, the larger siblings have the Top Cowl Service door that lets owners check and fill the oil without having to remove the cowl. Speaking of the cowl, the motors are available in traditional Phantom Black and shades of white with colored accent panels.

To put the power to the water, the V8 series engines have a 5.4-inch diameter gearcase that is an evolution of the lower unit used on the L6 Verado. The V8 AMS Verado is available with 1.85:1 or 1.75:1 gear ratios while the CMS-designated FourStroke and Pro XS all have 1.75:1 gearing.

For multiple engine installations, the V8 models mount on 26-inch centers and Pfeifer said that meeting this specification was a priority from the start of the project. The motors are available in 20-, 25- and 30-inch shaft lengths so they can be used on offshore and inshore saltwater fishing boats, bass models, pontoons, runabouts and commercial applications.

 The new motors replace the 2.5L and 3.0L OptiMax, L4 Verado and L6 Verado models in the same horsepower ratings.

 As for the question that’s on everybody’s minds, when will a “big” Mercury outboard be introduced, the company will keep its 350- and 400-hp supercharged Verado models, but the boys in black aren’t saying anything beyond that. The 350-hp Verado will remain in the Mercury Marine portfolio while the Verado 400R will be a Mercury Racing product.


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