Your Complete Guide To The Boxer Engine


Is the 'flat engine' too good, or just too good to be true?

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Any way you look at it, an internal combustion engine is one big air pump that works on an established set of principles, but there are a few ways of achieving the same result, with the boxer engine being one of the more interesting. There are numerous engine formats around, including favorites such as the inline and V, but there are also a few outliers, such as the pistonless rotary engine and the flat or boxer motor. Here we will take a look at what makes the flat engine so good and bad, and we'll also list a few of our favorite boxer-powered cars, so hold onto your vape pens!

Boxer Engine Porsche

What Is a Boxer Engine And Is It Right For You?

Horizontally opposed boxer engines are best known for featuring in Porsche and Subaru cars, but how exactly do they work, and what makes the boxer configuration so unique? Flat-type engines, whether it's a flat-six engine or a flat-four, all feature opposing cylinders on each side of a central rotating crankshaft at a 180-degree angle. This setup is also known as a 180-degree V engine. This means that opposing cylinders move in and out at the same time. Imagine two boxers throwing a bunch of jabs and straights at each other. Get the idea now? Boxer engines are beautifully balanced engines and therefore don't require any counterweights on the crankshaft or balance shafts. Boxer engines with fewer than six cylinders feature a rocking couple (to create rotation without accelerating the engine's center mass). This kind of engine has been successfully used in aircraft since its inception and is also popular in motorcycles.

Flat-6 Engine Porsche

Advantages And Disadvantages of the Boxer Engine

As with any other engine layout, horizontally opposed piston engines have certain advantages and disadvantages. From their low center of mass to occasional complexity, these opposed engines bring a lot to the table but are still seen as more of an enthusiast's choice.

Pros and Cons

  • Balance: Boxer engines have excellent inherent balance thanks to the pistons working together in perfect harmony. This is not only good for a refined and smooth drive but also places less strain on other parts such as the crankshaft and engine mountings.
  • Low center of gravity: There's a reason why the boxer engine is also known as the "flat engine." These motors are designed to be flat instead of tall, which helps lower the car's center of gravity. This is an excellent benefit in performance cars, as it aids in handling and weight transfer.
  • They sound cool: Have you ever heard an air-cooled Porsche boxer engine screaming around a race track or a Subaru WRX STI blasting down a quiet suburban street? These engines sound fantastic and have a unique thrum that is instantly recognizable.
  • Size: The boxer engine might save some space up top, but it sits wide in the engine bay, which can pose a few issues - finding space for critical parts such as the steering rack can be difficult. These engines can also cause airflow obstructions, leading to engine damage on rare occasions.
  • Complexity: A boxer engine has double the number of camshafts and head gaskets and is generally more difficult to work on than other types of engines. The fact that the entire engine needs to come out when replacing the head gaskets in some vehicles should give you a good idea of the aches and pains that go into owning a boxer-powered car.
  • Maintenance: The benefits might be numerous, but it takes a lot of care to keep a boxer engine running correctly. A boxer-six, flat-4 engine, and even a horizontally opposed diesel engine require more parts than their inline counterparts, making maintenance a bigger job. Things like double timing belts and head gaskets are the reason why most shy away from working on their boxer-powered vehicles.
Flat Engine Porsche

Best Boxer-engined Cars

There are all types of boxer-powered vehicles running around, from exotic supercars to humble family station wagons. As boxer engine technology has developed, innovations in the field have allowed companies to build some of the best-rated performance engines ever seen. Here are some of the best cars with boxer engines.

  • Ferrari Testarossa - It's hard to ignore the Testarossa: its wedge design screams 80s, and under the hood is a glorious-sounding flat twelve engine that delivers impressive numbers. The Testarossa was produced from 1984 to 1991 and featured a 4.9-liter Tipo F113 G longitudinally mid-mounted flat-12 engine producing a maximum of 434 horsepower. This allowed the Testarossa to accelerate from 0 to 62 mph in 4.7 seconds and top out at 196 mph.
  • Subaru Impreza 22B STI - This car has to be one of the most famous Subaru models of all time. Produced between March and August 1998, only 424 examples of the 22B STI saw the light of day. The 22B featured a heavily modified H4 engine named the EJ22G which produced 276 hp and 268 lb-ft of torque. Power was sent to all four wheels via a five-speed manual transmission. This car was built to celebrate Subaru's WRC successes and has become massively collectible.
  • Toyota 86 - When Toyota decided to get back into the RWD sports car game, it chose to partner up with Subaru, who developed the flat-four engine for both the Toyota 86 and Subaru BRZ, but also for the Scion FRS. These lightweight sports cars are powered by a 2.0-liter four-cylinder boxer engine featuring direct injection and produce close to 200 hp and 151 lb-ft. The boxer engine's low center of gravity gives the 86 beautifully balanced handling.
  • Porsche 718 Cayman GT4 - Porsche builds some of the best flat engines in the world, and a sterling example is in the Porsche 718 Cayman GT4. This superior track weapon is powered by a 4.0-liter flat-6 engine that produces 414 horsepower and 309 lb-ft of torque. Power is sent to the rear via a short-throw six-speed manual. With an 8,000 rpm redline, there are few cars with such a unique soundtrack.
Flat-4 Engine Subaru

FAQs About The Horizontally Opposed Engine

Should I buy an opposed-engined car if I don't have a lot of mechanical skills?

New horizontal-engined cars will be just as reliable as their counterparts, but a maintenance plan would be a good idea. Older boxer engines require more engine oil and attention, so if you're not mechanically skilled, and don't have the budget for big bills, then we'd suggest avoiding these engines.

How expensive will maintenance be?

Boxer engines will naturally be more expensive to maintain due to using more parts and being slightly more complicated to work on. Simple tasks such as removing spark plugs can be a significant ordeal in a boxer-engined car.

Are boxer engines fuel efficient?

Modern boxer engines are relatively fuel-efficient but can't match the numbers of traditional inline motors. Boxer engines are mainly focused on performance.

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