MerCruiser
8.1S Horizon (370-hp)

BoatTest.Com Video Library


First Name:*
Last Name:*
Email:*
Zip Code:*
Country:*
Boat Size:*	Under 30 Feet Over 30 Feet


Terms and Conditions

We do not SPAM, nor do we sell, rent, or give your member information to ANY third party without your permission. You will receive our FREE weekly e-newsletter, which you may easily cancel at any time

Most of our content, boat tests and videos are available for free viewing. However, there is a small charge for access to archived videos and tests.

Add/View Feedback or Comments about 8.1S Horizon (370-hp)

Related Videos

Only Builder in Class Up in 2007 (Cobalt) Cobalt Was the Only Builder in Class Up in 2007. Paxson St. Clair CEO of Cobalt talks to BoatTEST.c...	Cobalt Will Offer Both Merc and Volvo Joystick Systems (Cobalt) Paxson St. Clair CEO of Cobalt says the company will offer both MerCruiser and Volvo Penta joystic...
Extra Cost with SeaCore (MerCruiser) Kevin Grodzki president of MerCruiser talks to BoatTEST about SeaCore's cost....	Cooling System Maintenance: 496 and 8.1L Engines (MerCruiser) Cooling System Maintenance: 496 and 8.1L Engines...
Understanding Electrical Systems (MerCruiser) Understanding Electrical Systems ...	Understanding Cooling Systems (MerCruiser) Understanding Cooling Systems ...
Inside Look: Bravo Two Drive (MerCruiser) Inside Look: Bravo Two Drive ...	Inside Look: Bravo One Drive (MerCruiser) Inside Look: Bravo One Drive ...
Inside Look: Alpha One Drive (MerCruiser) Inside Look: Alpha One Drive...	Inside Look: Alpha One Drive (MerCruiser) Inside Look: Alpha One Drive ...
Mercury Racing History Video (MerCruiser) Mercury Racing History Video ...	Cooling System Maintenance: 496 and 8.1L Engines (MerCruiser) Cooling System Maintenance: 496 and 8.1L Engines ...
MerCruiser Marine Interview (MerCruiser) Kevin Grodzki Interview on MerCruiser Marine...	Pat Mackey's Mercury Legend (Mercury) Pat Mackey talks about his accomplishments at Mercury Marine. ...
When Will Merc Have a 5-Year Warranty as Standard? (Mercury) Jeff Hammond editor-in-chief of BoatTEST.com speaks with Pat Mackey about his thoughts on 5 year wa...	Why was SeaCore So Long in Development? (Mercury) Mercury Marine president, Pat Mackey speaks with Jeff Hammond of BoatTEST.com on the development of...
Impact of Employee Costs on Future Engine Prices (Mercury) Mercury Marine president, Pat Mackey speaks with Jeff Hammond of BoatTEST.com on the impact of empl...	What is Happening with Boat and Engine Pricing? (Mercury) Mercury Marine president, Pat Mackey speaks with Jeff Hammond of BoatTEST.com on the topic of boat ...
How did MerCruiser Beat Volvo with Sterndrive Joystick? (Mercury) Mercury Marine president, Pat Mackey speaks with Jeff Hammond of BoatTEST.com about how MerCruiser ...	Mercury Outboards and Saltwater Applications (Mercury) Mercury Marine president, Pat Mackey speaks with BoatTEST about Mercury outboards and saltwater app...
Making a Supercharged Outboard Fuel Efficient. (Mercury) Mercury Marine president, Pat Mackey speaks with BoatTEST about making a supercharged outboard fuel...	Interview with Mercury President (Mercury Marine) Mercury Marine president Pat Mackey talks about the company's global distribution....
Small Craft Binnicle Control (Mercury Marine) Review on Mercury Marine's small craft digital binnicle control....	Interview with Pat Mackey (Mercury Marine) Mercury Marine president Pat Mackey talks about the changes going on and what people can expect dow...
Earthrace Interview Miami 2007 () Interview with Pete Bethune the owner and skipper of Earthrace at the Miami Boat show 2007. This wa...	Skyhook Technology (Formula) What is MerCruiser's "Skyhook" technology? ...
Axius Technology (Formula) The technology behind the Axius system. ...	Axius Joystick (Formula) Interview with Louis Posner, Business Development Manager at Mercury MerCruiser talks to us about t...
Skyhook Now Available (Formula) Skyhook is now available on MerCruiser Axius Joystick Systems. ...	Axius Joystick (Formula) Formula Jumps on Axius Joystick...
Moving Towards Family-Oriented Boats (Fountain) Is Fountain really moving towards family-oriented designs? Reggie fills us in. ...	MerCruiser Propeller Commerical (MerCruiser) MerCruiser takes you through design, manufacturing and performance of their propellers....
MerCruiser Scorpion 350 (MerCruiser) Captain Rob Smith takes us on tour of the Scorpion 350 and a detailed look at the catalytic convert...	SeaCore is Slowly Being Accepted (MerCruiser) Kevin Grodzki president of MerCruiser talks to BoatTEST about its SeaCore technology slowly being a...
No Demand for Gas Engines with Pod Drives (MerCruiser) Kevin Grodzki president of MerCruiser talks to BoatTEST about the lack of demand for gas engines wi...	Joystick Technology Coming to Outboards Next? (MerCruiser) Kevin Grodzki president of MerCruiser talks about joystick technology coming to the inboard market ...
MerCruiser SmartCraft Review (Mercury) Capt. Robert Smith of BoatTEST.com reviews Mercury's new SmartCraft technology. ...	When is the Joystick Coming to Outboards? (Mercury) Mercury Marine president, Pat Mackey speaks with Jeff Hammond of BoatTEST.com on whether he thinks ...
What is the Future of 2-Stroke Outboards (Mercury) Mercury Marine president, Pat Mackey speaks with Jeff Hammond of BoatTEST.com about the future of 2...	Mercury's Chinese Operations (Mercury) Mercury Marine president, Pat Mackey speaks with Jeff Hammond of BoatTEST.com about building engine...
Has the Verado Been Accepted by Bass Fishermen? (Mercury) Mercury Marine president, Pat Mackey speaks with BoatTEST about the Verado outboard being used by b...	Why Develop a Supercharged Outboard Motor? (Mercury) Mercury Marine president, Pat Mackey speaks with BoatTEST about developing a supercharged outboard....

OVERVIEW
BOATS TESTED
SPECS
PHOTOS
FEEDBACK

8.1S Horizon (370-hp)
This is the big-gun in the MerCruiser line of recreational powerplants. It's designed to put real performance into mid-size express cruisers.

Fast Facts
Propshaft HP	370-hp
Configuration	V8
Aspiration	Normal
Displacement	8.1 L /496 CID
Bore & Stroke	4.25 x 4.38
Fuel System	Sequential Multi-Point Electronic Fuel Injection
Base Engine Weight	1130 lbs.
Length/Width/Height	47 x 33 x 24
Max RPM@WOT	4200-4600
Warranty	3-year

Key Features

Mercury-exclusive PCM 555 high-speed microprocessor that optimizes fuel mixture, knock control and ignition timing independently for each cylinder, re
Distributorless ignition system that improves timing accuracy and eliminates mechanical timing adjustments.
Closed cooling with 5-year coolant.
Redesigned exhaust system with aluminum manifolds and stainless steel elbows that is 65 percent lighter and more corrosion-resistant.
Exclusive Engine Guardian protection senses potential problems and virtually eliminates the chance for engine damage due to overheating, low oil press
Long individual runner intake manifold design provides optimum torque and horsepower for demanding marine applications
Sequential fuel and spark control maximizes performance from every engine cylinder
Convenient remote oil filter location makes oil changes cleaner and makes periodic service simple and less work
Cartridge-type water-separating fuel filter helps protect fuel system and engine against damage

Boats Tested with this Engine
Sea Ray 340 Sundancer
Carver 346 Motoryacht
Larson Cabrio 370 Day Cruiser
Sea Ray 360 Sundancer
Formula 37 PC (2005 - )
Maxum 3700 SY Sport Yacht
Meridian Yachts 368 Motoryacht (2009-)
Meridian Yachts 381 Sedan
Sea Ray 38 Sundancer (2006-)
Sea Ray 380 Sundancer -- GASOLINE
Sea Ray 40 Sundancer
Regal 4060 Commodore
Cruisers Yachts 415 Express - GAS (2002-)

MerCruiser 8.1S Horizon (370-hp)
Propshaft HP	370-hp
Max RPM@WOT	4200-4600
Dry Weight	1130 lbs.
Length/Width/Height(in)	47 x 33 x 24
Displacement (liters/cu.in)	8.1 L /496 CID
Aspiration	Normal
Cylinders/Configuration	V8
Bore & Stroke	4.25 x 4.38
Alternator Output Rating	65 amp
Shaft Length	~
Fuel Type	87 Octane
Fuel System	Sequential Multi-Point Electronic Fuel Injection
Exhaust System	Long Runner Cast iron Manifolds w/316 ss jt elbows
Ignition System	Distributorless Ignition
Cooling System	Closed Cooling, Brass Sea Water Pump
Electronic Engine Display	Yes


MerCruiser 8.1S Horizon (370-hp) Multiport Injection (MPI) inboard models are now available with optional Digital Throttle and Shift (DTS). DTS eliminates all helm maintenance and provides silky-smooth shifts for the life of the prod

Have you used this engine? Give us your feedback/comments.

R. Brant	9/22/2009 11:34:29 PM
BTW, before I am asked these engines have been gone through several times and the props have been off the boat twice and everything checks to specks!!!

R. Brant

9/22/2009 11:31:02 PM

I repowered with these engines in my SeaRay 370 EC. Love my boat and she is good to me however these 8.1's are pure PIGS. Under ideal conditions these things do not perform now where close to Mercury's claims. Very disapointed in performance and customer service. I am going to have these pigs pulled out and going to repower again this time with Cummins like I should have done in the first. Stupid me!!!!!

A. Rodriguez	7/25/2009 9:02:20 PM
fuel filter

H. Di Palma	8/18/2008 4:08:47 PM
Dear sirs I have 2 Mercrusier 8.1L 2000 Please let me know if this motors has the PCM 555 and how can I increase the HP.Regards,Humberto Di Palma

Already a member?

Key Features

MerCruiser 8.1S Horizon (370-hp)