Mercury MerCruiser
8.2 MAG
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Mercury MerCruiser 8.2 MAG Main Video


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Mercury MerCruiser 8.2 MAG Mercury MerCruiser 8.2 MAG main video
The latest evolution of big block engines from the team at Mercury MerCruiser is the Catalyzed 8.2L sterndrive. This engine is available in two variation, the first being the 8.2 MAG ECT which produces 380 HP and the second being the 8.2L MAG H.O. ECT which produces 430 HP. This engine is designed to run on regular 87 octane gasoline with up a 10% ethanol. It was also designed with multi-port electronic fuel injection (EFI) and sequential fuel injection with digital throttle and shift. This engine has several drive options which include the Bravo One X, Bravo One XR, Bravo Two X, Bravo Three X and Bravo Three XR

Key Features

  • Sequential multi-port fuel injection
  • Exclusive GEN III cool fuel module
  • High output alternator
  • Drive lube monitor
  • Exclusive engine guardian
  • Dry-joint exhaust design
  • Color-coded service points
  • Top Mount oil dipstick
  • Convenient air actuated water drain system
  • Full closed cooling


Mercury MerCruiser 8.2 MAG (Sterndrive) Specifications
Horsepower 380-hp
Displacement (cu/cc) 502.00 cu / 8,226.31 cc
Number of Cylinders 8 Cylinders
Configuration V-8
Fuel Delivery Fuel Injected
Cooling System Closed
Weight (lbs/kg) 1,122.00 lbs / 508.93 kg
Charging System 65
Full Throttle RPM 4400-4800
Engine Control System Electronic

Mercury MerCruiser 8.2 MAG Captain's Report

Mercury 8.2 MAG
The 8.2 tips the scale at 1,122 lbs. (509 kgs.) without the lower unit. This engine is the biggest, meanest block of iron in the neighborhood.

First, the Philosophy…

While Detroit is down-sizing both cars and engines and there is a growing global trend of getting by with less, Mercury Marine has made a conscious decision not to get ahead of reality -- and the marine market -- when it comes to propulsion. While some boats are getting lighter and there may be a trend for smaller boats, the fact remains that there is a big difference between pushing a boat through a fluid called water and rolling a car through a "fluid" called air. Boats simply need a lot more power than automobiles and always will.

Made in Detroit. Virtually all marine gasoline inboard and sterndrive engines come from blocks cast for vehicles made in Detroit. Because they are mass-produced for cars and trucks these blocks are far less expensive than if the marine engine makers cast them. (In fact, GM could theoretically cast all of the marine inboard and sterndrive engines needed annually in one eight-hour shift.)

As GM engine technology changes Mercury Marine has begun to design and manufacture its own engines specially for today’s marine applications. The 8.2 MAG is the first engine completely dedicated to Mercury’s own design and its exclusive use.

The only item purchased from GM is the bare 8.2L cast iron block which has an exclusive cylinder honing process owned by Mercury. This design is intended to improve long term endurance and low oil consumption.



Mercury 8.2 MAG

Made or Assembled in Fond du Lac.

All 8.2 components are Mercury designs and Mercury patents. It uses world class vendors that supply these components to its exact specifications.

Some of the more notable components are: the exclusive aluminum cylinder heads, forged steel crankshaft, roller lifter camshaft, lightweight aluminum piston rings, forged connecting rods.

The High-Inertia Induction System and the exhaust system are all Mercury designs and castings. Final complete assembly is done in Fond du Lac at the Mercury plant.

A Mushing We Will Go. The prospect of smaller and smaller engines for cars does not bode well for the marine industry which can only make its boats so light. Smaller gas engines would mean that boats will need multiple engines or just go a lot slower. Typically, cruisers up to as much as 42' or so have used big block V-8 engines and need them to get on plane and be able to travel in the high 20s. The alternative is much more expensive diesels or mushing along with under-powered gas engines.

Likewise, sportboat and express boat builders need the powerful V-8s to satisfy their performance-oriented customers. Some just like to go fast, but others need the performance because they have limited leisure time and must get there and back in a weekend.

Mercury Racing. By continuing to marinize the 8.2 L block Mercury Marine is making available a 430-hp, high-torque engine that has proven itself to be the best solution to many boaters' wants and needs. This engine, together with those produced by the Mercury Racing division which makes gas engines up to 1350-hp, assures the marine industry a reliable source of high-horsepower engines.

The Mission of the Mercury 8.2 L MAG

The 8.2 L Mercury sterndrive engine is the largest sterndrive block now on the market and its mission is to provide maximum horsepower and high-torque for a broad range of applications. The 8.2 L MAG ECT model produces 380-hp at 4600-4800 rpm. The 8.2 MAG H.O. ECT model produces 430-hp from 4600-5000 rpm.

These two engines are appropriate for small sportboats, large sportboats, express cruisers and express fishboats, sedans and cruisers, high-performance boats, offshore race boats, small convertibles, houseboats, ski and wakeboard boats, and utility boats of all kinds.



Mercury 8.2 MAG
The Gen II Mercury 8.2 L engine ready to ship. While manufactured on an assembly line they are pretty much put together by hand. Only a few thousand are made each year.

Distinguishing Features

● Biggest Block on the Market. The Mercury 8.2 L is developed and built by Mercury exclusively for marine applications needing high horsepower and high torque. No other large, mass-market engine maker offers such a high-horsepower engine to the marine market.

● Tested and Proven in Offshore Racing. The 8.2 L block is the same one modified by world-famous Mercury Racing to provide high-horsepower engines for offshore racing boats all over the world. In fact, Mercury Racing has souped-up the 8.2 block to turn out as much as 700-hp. There is nothing tougher on engines and drives than offshore racing and Mercury Racing has had 50 years of experience in that field to find out the weak links in engines and drives -- and build equipment to handle that demanding environment.

● Dry-Joint Exhaust Design. This system separates cooling water and exhaust gas at junctions to prevent water leaks from reaching critical engine components.

● Gen II Cool Fuel Module. The new "cool fuel" module uses water to cool the fuel delivery system and thereby provides higher psi fuel to the injectors. This prevents vapor lock. The unit also has a water fuel separating system. All of this is to help prevent a lost weekend on the water.

● Air-Actuated Water Drain System. This patented system makes periodic maintenance easier and allows boaters to extend their boating season into cooler months. When a freeze is feared, simply use the pump provided with the engine to clear the raw water cooling system in two minutes, according the Merc techs.

● Optional SeaCore Anti-Corrosion System. Mercury's anti-corrosion system is generally regarded to be the best in the industry. It consists of a patented low-copper aluminum alloy (XK360) used in any component that touches the water, a special metal treatment, the MercFusion paint process, 300 Series stainless steel hardware and the incorporation of the MerCathode system, among other things.

● 4 Ways to Exhaust the Engine. The 8.2 L engine can be exhausted through the prop hub or through the transom, and it can be switchable from under water or through the transom.

● Lower RPMs For Max Horsepower. The rated 380-hp is developed from 4400 to 4800 rpms, and from 4600 to 5000 rpms for the 430-hp H.O. model.

● Higher Torque. Because the 8.2 L engine has 36% greater displacement than any other 380-hp engine on the market it naturally has significantly greater torque. This is particularly important in "0-to-plane" times.



Mercury 8.2 MAG
This is Mercury Racing's 700-hp high-performance engine. Beneath that blue supercharger and all of the other components can be found the same 8.2 L block that is used in the Mercury's 380- and 430-hp models.

● Gen II Improvements of the 8.2

● All Major Service Components on Top. Cooling water, engine oil, gear oil, and fills are all on the top of the engine. Reservoirs are in translucent containers for instant checking. The cooling reservoir is easier to replace. The exclusive drive lube oil reservoir is larger and has an audible alarm for low oil levels. Filters are easier to reach.

● Improved Oil Change System. Now it is easier to change oil remotely without a mess.

● New Air Intake Silencer. This new device is said to lower the noise during mid-range operation by 2 dbA. Mercury techs say it makes a noticeable difference in noise at the helm which, if true, would indicate an effective reduction of about 5 dbA.

● Catalyst Reduction. Instead of three catalysts per side there is now only one. This not only improves reliability, it also lowers cost and simplifies maintenance.

● New Intermediate Exhaust Elbows. These elbows connect to the stern and make installation for builders easier and increases the durability of this critical system.

● New Poppet Valves. One poppet valve is now installed on each exhaust bank to improve water flow and enhance cooling for longer engine life.



Mercury 8.2 MAG
This 8.2 L MAG 380-hp sterndrive engine.

Major Features

● Engine Guardian. This system senses potential problems, alerts the operator, and even reduces engine power when needed. The elements monitored are oil pressure, coolant temperature, seawater pressure, voltage, rpms, knock, exhaust temperature, and drive lube oil levels. The exclusive Engine Guardian protection system provides protection from overheating, low oil pressure or low drive lube levels. Engine Guardian virtually eliminates any chance for engine damage, according to the manufacturer.

● High-Inertia Induction System. This unique design is intended to pack more air into the cylinders just as the valves open for greater combustion.

● Exhaust System. The system has tuned runner exhaust manifolds for reduced back pressure and 316 stainless steel tubular dry joint elbows for longer engine life.

● Cooling System. The 8.2 MAG has a closed cooling system, long-life, 5-year anti-freeze, and a large capacity brass sea water pump that is manufactured by Mercury.

● Multi-port Fuel Injection (MPI). This sequential system measures out the precise amount of fuel needed for all running conditions for greater fuel efficiency. It promotes easy starts no matter what the temperature and gives good throttle response.

● 4-Year Warranty With SeaCore and IQ Certification. 8.2 L engines with the optional SeaCore anti-corrosion system, which are installed by an IQ (Installation Quality) certified boat builder, carry a 4-year, non-declining warranty.

● Color-Coded Service Points. By having all regular maintenance systems color-coded, owners can easily check fluid levels to fill reservoirs when needed.

● What Type of Boats Should Use the 8.2 MAG?

The Gen II 8.2 MAG and 8.2 MAG H.O. are appropriate options for many different kinds of boat from sportboats, pontoon boats, ski boats, express cruisers, express fishboats, to sedans, high-performance, and race boats, among others. Below are four examples of how these engines performed in boats that we have tested--

"Loaded" Sportboat -- 1 x 430-hp MAG H.O.

Mercury 8.2 MAG

Small, Luxury Sportboat

The above test numbers are from a luxury sportboat which we tested in moderately hot conditions at sea level. The boat had a test weight of about 6,000 lbs. (2,727 kgs.), an 8'6" beam (2.59 m) and a deadrise of 20-degrees. She had a Bravo III X lower unit.

Going 1st Class. The owner of this boat is the type of person who wants to go first class and have a boat that is the envy of everyone on the lake, own one of the fastest boats on the lake, and be able to tow a heavy wakeboarder with a crowd of friends aboard. The 430-hp MAG H.O. with its high torque at the low end to pull a load and its sheer horsepower for top-end speed filled the bill.

Large Express Cruiser #1 -- 2 x 430-hp MAG H.O.

Mercury 8.2 MAG

Luxury Express Cruiser We tested a luxury 38' (11.58 m) express cruiser with twin 430-hp MAG H.O. engines with virtually no expense spared on equipment and amenities and got the test numbers seen above. The boat weighed 18,625 lbs. (8,465 kgs.), had a 12' (3.66 m) beam, and 18-degree deadrise at the transom and used Bravo III X drives.

Engine Upgrade. This boat cost only $11,000 more for the 100 extra horsepower of the H.O. engines over the standard 380-hp 8.2 MAGs from this builder. Since keeping cost down wasn't the objective of this owner, why not get all of the horsepower possible? Why settle for second best?

We recorded a remarkably quick time-to-plane for such a heavy boat of 4.8 seconds and she hit 30 mph from a standing start in 11.6 seconds. Note that at her best cruise speed she got nearly 1.0 mpg.

Large Express Cruiser #2 -- 2 x 380-hp MAG

Mercury 8.2 MAG

Bigger Express Cruiser

Equally as impressive was a similar-sized express cruiser which weighed about 19,000 lbs. (8,636 kgs.), had a 21-degree deadrise at the transom and had a WOT that was only 3 mph slower than the twin 430-hp engines tested in express cruiser #1.

Why was that impressive if she was 3 mph slower? In addition to being heavier and having a deadrise 3-degrees deeper, the day we tested her it was 99-degrees F (37 C) with 90% humidity at sea level. Powered by twin 380-hp 8.2 MAGs the second express cruiser had a total of 100-hp less!

Hot Weather Performance. Hot, humid days like the one we experienced on test day robs horsepower from any engine and can make big, heavy boats sluggish. (Both higher temperatures and higher humidity reduce the amount of oxygen in the air, thus reducing combustion potential.)

But express cruiser #2 with twin 380-hp engines was able to handle the heat and humidity, the extra weight without a dramatic drop-off in performance. Note that her best cruise fuel consumption was even slightly better than the first boat tested. That speaks well of this boat's hull shape and of the sheer muscle in the big-displacement 8.2 MAG.

Bigger is Better. This engine's big lungs are 2.0 liters or 32% greater in capacity than the next largest marine gasoline engine on the market. That means it can take in 32% more oxygen on every power stroke than an engine rated at the same horsepower with a 6.2 liter displacement. As the old rhyme goes: "There's no replacement for sheer displacement," and this test seems to indicate that.

Crossover Cruiser -- 2 x 380-hp MAG

Mercury 8.2 MAG

Mid-Size Vessel

This 31' (9.44 m) crossover cruiser is one of the new breed of boats that has a bow seating area, but also has accommodations below. Our test boat had a weight of 11,182 lbs. (5,082 kgs.), a 9'6" (2.90 m) beam and 22-degree deadrise at the transom. This lighter, narrower boat at normal testing temperatures at sea level had a WOT speed of 58 mph. Equally as impressive was her best cruise speed and gas mileage at 3500 rpm where she went 41.3 mph, getting 1.43 mpg.

High Speed at Moderate Revs. Thanks to her deep-V bottom this boat will be able to cruise comfortably in a light to moderate chop at 41 mph getting good fuel mileage at a reasonable rpm. Note that her noise level was only 79 dbA at 3500 rpm.

Silencer and Lower Revs. That relatively high cruising speed at 3500 rpm was possible because of the 8.2's huge displacement. The relatively low noise levels of this crossover boat -- about 10 dbA less -- than the other two express cruisers at the same speed, occurred at least to some degree because she was turning fewer rpms as well as because of the new Gen II intake silencer.

Which Engine is Best: the 8.2 MAG or 8.2 H.O. MAG?

WOT. The answer is -- as demonstrated above -- both 8.2 MAG and the 8.2 H.O. MAG have a strong story to tell. Clearly if WOT speed is the object the 50-hp extra horsepower should always propel the boat faster. How much faster? A rule of thumb in the marine engine business is that it takes 12-hp to equal + 1 mph. If that is true then, the H.O. version of the 8.2 is worth + 4.16 mph.

Heat and Humidity. Boats used on hot, humid days lose horsepower because there is simply less oxygen in the air. In the example above of the "Large Express Cruiser #2" her engines actually had only 91.1% of the horsepower they would have had at 77-degrees F (25 C) and no humidity at sea level. For that reason, many people who boat in hotter conditions like to start with as much horsepower as they can pack aboard.

Cruising Speeds. Most people normally travel at cruising speeds, say something between 3000 and 4000 rpms. At these speeds most boats will not be creating anything like their max rated horsepower, so why pay for horsepower that will rarely be used? But what if the boat is heavy either because it was built that way or it is loaded with guests? And virtually all boats get heavier over time. Obviously the engine will have to work harder and burn more fuel. And if it is a hot and humid day the engine will be starting with less horsepower.

Towing Speeds. Most sportboats are used for towing, either a skier or wakeboarder or a tube toy of some sort. Typically, speeds for these activities are from 18 mph to 23 mph. Clearly both the 380-hp and 430-hp models are up to the task. However, in this application, time-to-plane times are important, particularly for novice, heavy, or weak towees. For these people fast times to plane can make the difference between getting up on the boards or not.

Time-to-Plane Caveat. Looking over some of the 2,000+ tests on BoatTEST.com will give most people a good idea of what sort of horsepower is needed to achieve the speeds desired for their application. However, sportboat owners planning on towing should bear in mind that our tests are done with just two people aboard (figure 425-lbs./193 kgs) and no one in tow.

With a heavier person on the end of the tow line and 8 people aboard, the time-to-plane times will be a lot longer. For that reason, horsepower and low-end torque should be carefully considered.

Options To Consider

DTS. These days we would not buy a boat over $50,000 that did not have a drive-by-wire system such as Mercury's Digital Throttle and Shift (DTS). Not only is this more reliable, more user friendly, needs no maintenance, is more precise, it is also the kind of feature that is important when it is time to sell the boat and move up. The boats with DTS will be the ones in demand and have the best chance to sell fast and for a higher price.

VesselView. On this one screen, dozens of data points can be displayed. The screen itself can be read in direct sunlight, it is intuitive, and one touch activates the data desired. Certainly all twin engine installations should have VesselView and we would make sure they are on premium sportboats.

Axius. Twin sterndrive engine installations are all good candidates for the Axius joystick feature. The benefits of a joystick for docking are well known. Boaters who have good boat-handling skills don’t need it, of course, but they should consider how mom and the kids feel about docking. Over the years, we have learned that the best way to get boating "buy-in" from the rest of the family is to put them at the helm as much as possible.

SeaCore. The Mercury SeaCore anti-corrosion system is pretty much state-of-the-art in recreational marine. Unfortunately, it is expensive. The reason is that with SeaCore many components are made of a special low-copper, high-strength aluminum alloy, there are many extra 316 stainless steel parts, a special anodized paint process, and a laundry list of other anti-corrosion measures that all cost money. People boating in freshwater don't need it. But we think any boat that is going to be kept in saltwater should have it unless it is hauled and thoroughly flushed out and washed down after every use, then kept on a trailer or rack.

SeaCore has a 4-year anti-corrosion warranty. An added benefit to getting SeaCore is that it automatically bumps up the factory warranty on the whole engine and drive system to as long as four years. (See below for more info.)

Smart Tow. SmartTow allows the boat's operator to plug in the towing parameters for each member of the ski or wakeboard team. A pre-selected speed for bringing up each skier can be plugged in along with the speed of the vessel that each individual prefers when doing tricks.

Details of the Warranty

The 8.2 MAG and 8.2 MAG H.O. each carry a standard 1-year limited warranty and a 3-year limited corrosion warranty. If the engine and drive system is installed by a builder that Mercury has designated "IQ Certified" then the engine warranty is for two years. In fact, we would not buy a boat from a builder that was not certified by the engine maker.

SeaCore. The standard SeaCore warranty on the 8.2s is three years for the engine, and the anti-corrosion warranty is bumped up a year to 4-years. If the SeaCore model is installed by an "IQ Certified" builder, the engine warranty goes up to 4 years, matching the anti-corrosion warranty. So, paying for SeaCore has the added advantage of "buying" more engine warranty.

5-Year Factory-Backed Warranty? From time-to-time boat builders in collaboration with Mercury Marine may offer a 5-year factory-backed warranty program for the engine. These are usually promotional incentives and only last for a month or six weeks. Nevertheless they are valuable and can lock-in worry-free boating for five years. It is best to contact the dealer for the boat desired to find out more about the possibility of an extended warranty.

Which Lower Unit is Best?

Mercury offers three drive units for the 8.2 L models: Bravo One X, Bravo Two X, and Bravo III X. All three units are "X" because the high torque of the 8.2 can best be handled by the extra beef put into the "X" systems.



Mercury 8.2 MAG
Bravo One X. Not available with Axius.

Bravo One X. This lower unit is fitted with a single prop and the system is designed for maximum speeds and it is typically used in offshore racing and high-performance applications. It is designed for speeds over 100-mph.



Mercury 8.2 MAG
Bravo Two X. Not available with Axius.

Bravo Two X. This lower unit swings a far larger prop but has a WOT speed limit that is typically in the mid-50s. It quite often provides a better time-to-plane and better fuel efficiency at cruising speeds. This unit is generally used for large cruising boats and houseboats.



Mercury 8.2 MAG
Bravo Three. Available with SeaCore and Axis.

Bravo Three X. This is the most popular drive for sportboats and express cruisers because it has good acceleration, competitive fuel economy at cruising speeds, and a decent high-end capability of 65-mph. However, its most outstanding attribute is the fact that the dual counter-rotating props keep the boat running straight with no side-walking or wander, something particularly important in single-engine sport boats. It makes docking these boats easier.


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