Is the Boxer, from 1921, Outdated Technology?

[David13]

In another thread, there were some questions about some things that made the boxer 'old fashioned'. Or outdated.

But I disagree.

Hydraulic valves.

I think there are a number of reasons to use adjustable valves, and that's why a number of vehicles still do.

Throttle cables.

I think that even with ride by wire you will still need to balance your throttle bodies, as there are still issues without regard to the cables.

So is there really any needed updating for the boxer?

dc

[beemerman2k]

Outdated or not, I love the characteristics of the boxer engine.

 

BTW, the boxer engine is not as old as you might think, I believe it debuted in 1923 :smirk:

[Huzband]

If the boxer motor were outdated, Porsche & Subaru wouldn't continue to update & race them. Successfully I might add. Nor would Der Moterrad.

[slipknot]

If the boxer motor were outdated, Porsche & Subaru wouldn't continue to update & race them. Successfully I might add. Nor would Der Moterrad.

 

And most of the prop driven aircraft in the world.

[12R12RT]

As a motorcycle engine? Yes, by 40 years or more. It became passe when Honda brought out the in-line four appliance.

 

But my gosh, it's a lovely thing. It has soul.

 

It won't be the same as a wasser boxer...

 

Tom

[beemerman2k]

Speaking of Honda, their Gold Wing is yet another boxer.

[tsp]

I love the boxer engine for its character but it also does have some basic advantages. First, it helps to lower the center of gravity of the engine. Also, having those cylinders sticking out in the air flow helps to keep things cool and keeps almost all engine heat from the rider.

 

I used to have an ST1300. Probably one of the finest engines that Honda has made (plus the GW engine) for motorcycles but for me... the boxer engine is my current choice.

 

YMMV,

tsp

Blog: www.swriding.blogspot.com

 

[JOHNNYWISHBONE]

As a motorcycle engine? Yes, by 40 years or more. It became passe when Honda brought out the in-line four appliance.

 

But my gosh, it's a lovely thing. It has soul.

 

It won't be the same as a wasser boxer...

 

Tom

 

nobody wants a mechanical rolex or omega either! hahaha!

boxer twin. the heart and soul of motored.

all other motorcycles are "less."

 

 

[AZRTRDR]

Old? Yes.

Outdated? Not even!

Kind of like pneumatic tires and internal combustion engines.

[John Bentall]

In another thread, there were some questions about some things that made the boxer 'old fashioned'. Or outdated.

But I disagree.

Hydraulic valves.

I think there are a number of reasons to use adjustable valves, and that's why a number of vehicles still do.

Throttle cables.

I think that even with ride by wire you will still need to balance your throttle bodies, as there are still issues without regard to the cables.

So is there really any needed updating for the boxer?

dc

 

I would want to know the true motive for someone knocking the "Boxer" engine. As BMW-bashing is a fairly fashionable passtime in the press, is the "speaker" just jumping on the bandwagon or justifying his purchase of another brand. There are plenty of truly great brands out there and lots of great adventure and sport tourers - each to his own choice.

For brand recognition and product marketing reasons, BMW is wedded to the Boxer for the foreseeable future as Triumph is wedded to the Triple and Ducati to the V-Twin. At least if you want the BMW experience without the Boxer motor, there are other models.

[Peter Parts]

Enough proud chest-beating, let's have some meat in this discussion.

 

Someone mentioned lower center of gravity.

 

I think an essential virtue is primary balance of the engine, esp. with a two-bearing crankshaft. As long as you are sitting on the engine on a bike, balance is a key advantage for anything longer than a trip to the milk store.

 

Although no big problem, the horizontal twins can puddle some the engine oil in the cylinders over-night.

 

BMW-corporate, not the smartest cookies in the jar, are unable to keep from adding complexity to what can be a simple, air-cooled engine.

 

Yup, 46 seasons and I love my Surbaru Impreza engine too.

 

Ben

[rclbaker]

Making a boxer engine requires innovative techniques as to fullfill actual requirements wrt emission, noise and power. Moreover, a boxer engine requires very skilled employees, because of the complex manufacturing (fabrication?) process.

 

As the market wants boxer BMW´s (and I am one of the devoted customers) BMW is admiringly capable in providing these techniques in actual applications.

 

I just bought a brand new R1200R. Compared with my airhead boxer the complexity of a "hemihead" boxer is overwhelming. But it fully gives the unique driveability of a boxer, augmented with the brilliant telelever: comfortable, excellent brakes & ABS, easiness of steering (a consequence of the crankshaft lay out) and.......still air cooled!

 

Just me!

 

 

 

[FLrider]

In another thread, there were some questions about some things that made the boxer 'old fashioned'. Or outdated.

But I disagree.

 

So is there really any needed updating for the boxer?

dc

 

I would want to know the true motive for someone knocking the "Boxer" engine. As BMW-bashing is a fairly fashionable pastime in the press, is the "speaker" just jumping on the bandwagon or justifying his purchase of another brand.

 

Easy man... I don't think he was boxer bashing.

 

I think his pondering brought out some great advantages of boxer engines.

[na1g]

What about the in-line 4, or (dare I say it?) the in-line-6. Y'know - like the new K-bikes? When was that engine architecture invented? Someone once said: "The more things change, the more they stay the same."

 

pete

[David13]

The other thread I was referring to is in the Camhead section, and titled Hemi Head?

In terms of the motive, I don't know, ask Bob, aka 1analguy.

I also disagree with what he says about hydraulic lifters. But it's another issue different from the original idea of "Hemi Head?"

That's why I started this thread, which was moved from Camheads.

dc

[Mister Tee]

I don't think the boxer concept is "outdated." Most piston light aircraft engines are air cooled boxers, which is a form that fits well within an aircraft cowling. Inlines and V engines really don't work well in aircraft applications.

 

From an engineering standpoint I don't know that I would agree that boxer engines are ideal for motorcycles. There are tradeoffs. You get good cooling characteristics from an air cooled boxer twin, but you also have side torque issues, and a more complex engine/clutch/transmission arrangement than you would have with an inline. But, BMW seems to make it work ok and so does Honda.

[Ron_B]

As a motorcycle engine? Yes, by 40 years or more. It became passe when Honda brought out the in-line four appliance.

 

But my gosh, it's a lovely thing. It has soul.

 

Tom

 

 

Elegantly put.

[leikam]

So is there really any needed updating for the boxer?

 

The essential question is what purpose any update serves? What problem does any proposed change solve? What goal does the boxer not meet effectively? What fundamental purpose does a motorcycle engine have?

 

Burning fuel for pleasure? Any engine will do that just fine.

[lkchris]

BTW, the boxer engine is not as old as you might think, I believe it debuted in 1923 :smirk:

 

Indeed, hence the 60th Anniversary special RTs of 1983.

[lkchris]

So is there really any needed updating for the boxer?

 

The essential question is what purpose any update serves? What problem does any proposed change solve? What goal does the boxer not meet effectively? What fundamental purpose does a motorcycle engine have?

 

Burning fuel for pleasure? Any engine will do that just fine.

 

Sure there is and it's the reason the next boxer will be watercooled, i.e. German noise regulations.

[GRB60]

How does water cooling reduce noise?

[dirtrider]

Afternoon Greg

 

A few reasons--

 

 

Liquid cooled in most cases allows tighter engines tolerances than air or air/oil cooling. Tighter operating tolerances equate to lower mechanical noise.

 

Next is the liquid surrounding the cylinders & sometimes in the cyl heads themselves. Liquid is a good medium to absorb or modulate mechanical noises. It is also somewhat decent at insulating engines noises.

 

Then you have the casting differences usually involved with liquid cooling. In most cases it takes added casting walls & passages to hold the liquid around the cylinders so the engine noise is somewhat further blocked by the added castings.

 

Then you have the elimination of direct contact cooling fins. All those air cooling fins add to the area that radiates engine mechanical noises.

 

It is very difficult to meet vehicle noise pass-by regulations with an un-shrouded air or air/oil cooled engine. It can be done but that usually takes full surrounding fairings that are baffled & covered with noise absorbent material.

 

Adding liquid cooling also stabilizes the engine operating temperature so that allows better fuel economy & tighter controlling of the engine exhaust emissions.

 

[John Bentall]

Adding liquid cooling also stabilizes the engine operating temperature so that allows better fuel economy & tighter controlling of the engine exhaust emissions.

 

Yes indeed! Just look at the roll-call of machines that have been killed of by emissions regs - all 2-strokes for a start!

[Peter Parts]

I think the oil-cooled boxer (perhaps with some thermostatic control added) is an interesting compromise. Seems to comply OK with advantages of air cooling and liquid cooling. Perhaps the oil-cooled boxer twin (without doo-dads like counter-rotating shafts) is a design that deserves a future.

 

You don't need to be an enviro-nut to believe two-strokes are an abomination on the environment.

 

Ben

[Penforhire]

I think OUR air/oil cooled boxer is indeed outdated. It is also charming and still very functional. It has character.

 

It may indeed have an edge in CG and it has some inherent balance (much as an I6 does) but I don't think it has many other industry-leading characteristics. Maybe nice torque at lower RPM? It is certainly not the most efficient in power/weight, fuel economy, HP/displacement or similar measures. It is not the smoothest (many sporting I4's are smoother). Heck, it doesn't even sound good, lol!

 

What it does have is a link to the past, along with its charm.

[DaveC]

Yes indeed! Just look at the roll-call of machines that have been killed of by emissions regs - all 2-strokes for a start!

 

Not entirely true.

I own a very nice 2-stroke snowmobile that is fuel injected, water cooled, and controlled by a modern ECU ignition.

 

The newer snowmobile engines offered by Polaris and Ski Doo are very nice engines with great power and low emissions.

[Peter Parts]

I own a very nice 2-stroke snowmobile that is fuel injected, water cooled, and controlled by a modern ECU ignition.

 

The newer snowmobile engines offered by Polaris and Ski Doo are very nice engines with great power and low emissions.

 

Aren't two-strokes always "dirty" because they need oil in the fuel to lubricate the piston? Please correct my ignorance of the current technology.

 

Thanks.

Ben

[realshelby]

Aren't two-strokes always "dirty" because they need oil in the fuel to lubricate the piston? Please correct my ignorance of the current technology.

 

Thanks.

Ben

 

Google Evinrude outboard motors and read about their etech two stroke engines. These meet California Emissions. Modern two strokes do not mix oil in the fuel. They have sophisticated oil injection systems that put the lubricant just where it is needed. I had a Yamaha 4 stroke and my friend had the Etec Evinrude. I never saw smoke come out of it. He used less oil over the time we had them than I did in the four stroke. With the two strokes lower weight, almost zero maintenance, and fewer moving parts I wouldn't be surprised to see a comeback. Especially in a motorcycle. This is from their website:

 

Three stars from the toughest emission standard in the world – the California Air Resources Board. Plus, we’re the only outboard to win the EPA Clean Air Excellence Award. No other brand of outboards produces fewer reportable emissions that the Evinrude E-TEC family of engines.

[Peter Parts]

For sure, nobody needs to dump oil into the gas tank anymore (like my 1956 Lambretta.... long ago). But doesn't the lubricant oil, however carefully sprayed into key areas, still get burned with the gas and out the tailpipe? And compared to modern water-cooled 4-stroken engines which lose very little oil between changes.

 

Maybe the total oil consumption of 2- and 4-strokes is the same, but the 4-stroke doesn't emit it at the tailpipe.

 

Air/oil-cooled boxer engines might have less temperature variation and hence less slop clearance needed in the pistons. So they might use less oil than say, certain v-twins. Anybody know?

 

Ben

[SageRider]

Maybe the total oil consumption of 2- and 4-strokes is the same, but the 4-stroke doesn't emit it at the tailpipe

 

If the 4-stroke doesn't emit it's consumed oil at the tailpipe, where does it go?

[dirtrider]

I think the oil-cooled boxer (perhaps with some thermostatic control added) is an interesting compromise. Seems to comply OK with advantages of air cooling and liquid cooling. Perhaps the oil-cooled boxer twin (without doo-dads like counter-rotating shafts) is a design that deserves a future.

 

You don't need to be an enviro-nut to believe two-strokes are an abomination on the environment.

 

Ben

 

Afternoon Ben

 

Almost all modern motorcycle engines are ultimately air cooled (all that I know of anyhow). It basically comes down to how the engine heat is carried to the ambient air.

 

Even so-called true 4 cycle air cooled motorcycle engines get a good portion of their cooling from the engine oil as that is what carries the bearing, piston, & some of the cylinder head heat to the engine sump then into the air surrounding the oil sump.

 

On the BMW oilhead that is still basically an air cooled engine design as no oil surrounds the cylinders & no major oil coolant passages in the cylinder heads. Just specific oil cooling used in the high heat valve area on the cyl heads to carry that specific heat away. Then the cooling oil is passed (pumped) through the external oil cooler. The oil used for that valve area cooling is pumped (with a separate oil pump) out of the sump so some of the sump oil is passed through the oil cooler as long (as the oil thermostat is open).

 

On true water (liquid anyhow) cooled motorcycle engines the cylinders have partial (or full) water jackets & liquid passages that allow coolant to surround or partially surround the cylinders to carry cylinder heat away. In most (but not all) cases there is usually some type of liquid channels or water passages in parts of the cylinder heads (usually near the exhaust valves) to carry that heat away to some sort of radiator or heat exchanger. Even then some high performance applications still have some type of external oil cooler to remove excess latent heat from the engine oil.

 

The place where the oilhead design is really lacking is for low speed high load cooling as there is no (or little) air flow over the engine at very low speeds.

 

The other (& probably the most important) issue is the oilhead design has no coolant surrounding the cylinders so still needs air cooling fins. So not only doesn't it get the liquid surrounding the cylinders for cylinder sound absorption it still has those nasty noise radiating cylinder fins.

 

I would imagine a fully sound absorbing covered fairing shrouded oilhead design could be made to pass the new U.S. noise pass-by standards & possibly pass the new very tough European noise pass-by regulations but how do they cheaply & efficiently cool a fully fairing covered engine at low speeds high loading without major ducting & added multiple cooling fans.

 

That would also mean covering up the thing that everybody seems to like & that is that nice ancient looking 2 cylinder boxer engine. By liquid cooling the new boxer they can leave a lot of the engine uncovered & still meet current & future noise emission standards.

 

True liquid cooling will also allow a bit more engine power, tighter engine tolerances to help meet the new tighter emission requirements & (a biggie) a more stabilized engine operating temperature so the emission output can be controlled sooner after start up, over more varied operating conditions, & in very cold weather. (air/oil cooled engines are very difficult to get up to emission friendly operating temperature quickly in very cold weather).

 

[David13]

SageRider

The 4 stroke doesn't emit burned oil at the tailpipe as, usually, it does not, and should not burn oil.

None of my Honda's ever did, nor some of my other bikes, including my BMWs.

The original design of the two stroke was that oil was in the gas. It lubricated the cylinders, and then was burned, with the gas, out the tail pipe.

I suppose there is a way to design the engine so that would not occur, and it would perform as clean as the 4 stroke.

According to some of the posts here, that is what the new design on the two strokes does. No oil burned.

But just used for lube.

On the boxer, or other 4 stroke, the oil returns down into the sump area. Rather than being burned with the fuel.

Burning oil indicates that something is not completely right. The stories you hear about BMWs burning oil do so because they do, not because they are supposed to. Because there is no such thing as the perfect engine.

dc

[SageRider]

My point was if a 4-stroke is consuming oil, it is either leaking or going out the tail pipe.

 

[David13]

Yes, but only as an aberration, not by design.

The two stroke originally, as designed, burned oil out the tailpipe.

As part of it's regular course of business.

dc

[Paul Mihalka]

The oil consumption of a good condition four stroke is when you change the oil. The consumed oil goes into the dump and not into the air.

[Peter Parts]

Oil is "consumed" in a 4-stroke when you change it, some creeps by the rings and is burned, and when some of it drips into your Ogala aquafir from engine drips.

 

In a 2-stroke, there's gotta be oil out the tailpipe (burned or not) that lubricates the rings, even if by some magic the crank bearings don't waste any.

 

dirtrider has clarified the main issues about cooling. He did not choose right now to take the bandwidth to delve into the trade-off of cost, weight, or complexity of competing designs.

 

So, what remains is some careful design judgment about how to balance the factors he has explained as well as their respective cost, etc. Which still leads me to think that a boxer twin with enhanced oil cooling is still a very, very good compromise.

 

Perhaps more than the tidbits of cooling dr has indicated are used on the Oilheads is needed in the future.

 

Ben

[David13]

Ben, as to the RT, I like mine. I sure do like me. A lot.

Paul

They talk about how oil, when taken out of a motor is recycled. Few people understand what that means.

Some is re refined into 'new' oil, or as good as new. But sold and marked accordingly.

As I understand it, the vast majority that is recycled, is ...

burned.

dc

[Little_Brit]

As I understand it, the vast majority that is recycled, is ...

burned.

dc

 

Properly though!

 

[RPG]

My 1150RT is 600 lbs, but when I let out the clutch it feels 100 lbs. lighter. That low center of gravity does wonders for a motorcycle. I'm a Boxer fan for life.

 

RPG

[macx]

I know there's been rumors popping up from time to time about water cooled boxers.

 

Well, in a recent copy of Motorcyclist magazine I saw what was reported to be a water cooled boxer, of course in disguise. Exhaust came out the bottom, intake on the top. Looked like a real picture, and it came with a reasonably realistic sounding explanation - more stable engine temps, lower emissions, etc etc.

 

http://www.motorcyclistonline.com/newsandupdates/motorcycle_news/122_1112_2012_bmw_r1200gs/index.html

 

http://bmwmcmag.com/2011/08/water-cooled-gs-spotted-again/

[doc47]

I don't think the boxer concept is "outdated." Most piston light aircraft engines are air cooled boxers, which is a form that fits well within an aircraft cowling. Inlines and V engines really don't work well in aircraft applications.

 

From an engineering standpoint I don't know that I would agree that boxer engines are ideal for motorcycles. There are tradeoffs. You get good cooling characteristics from an air cooled boxer twin, but you also have side torque issues, and a more complex engine/clutch/transmission arrangement than you would have with an inline. But, BMW seems to make it work ok and so does Honda.

 

When aren't there? EVERY design is a tradeoff.

[Joe Frickin' Friday]

From an engineering standpoint I don't know that I would agree that boxer engines are ideal for motorcycles. There are tradeoffs. You get good cooling characteristics from an air cooled boxer twin, but you also have side torque issues...

 

What side torque issues are we talking about? If you're talking about the chassis yaw torque associated with the relative front-to-rear offset of the cylinder bores, yes, that's an issue, but a pretty minor one. An inline 4 eliminates this by having the 1 and 4 pistons in sync and the 2 and 3 pistons in sync (but 180 degrees out of sync with 1 and 4). The Goldwing's 6-cyl boxer can't fix the problem.

 

If you're talking about chassis roll torque associated with the crankshaft's torque output, then no. We've had these discussions before, and if the entire driveline is taken into consideration, there is no net torque on the chassis except as relates to crankshaft angular acceleration (which doesn't absorb much of the engine's output unless you're just revving the engine with the gearbox in neutral).

 

...and a more complex engine/clutch/transmission arrangement than you would have with an inline.

 

What is intrinsically more complex about a boxer engine's driveline as compared to a longitudinally-mounted inline four-cylinder, or a transverse-mounted four-cylinder, or any other engine, e.g. Harley's V-twin?

[Mike]

Claiming no engineering expertise at all, I can't see why the horizontally opposed twin configuration would be viewed as outdated. Certainly, that engine from 1921, but not the basic configuration.

 

It actually seems to have some enduring practical advantages, particularly with regard to a lower center of gravity.

[MotorcycleWriter]

I think the Slant-6 is ready for a comeback.

[effexer1]

If they water cool the boxer, will it sound as bad as the Suburu? Those things sound terrible when under load at low rpm.

[Peter Parts]

If they water cool the boxer, will it sound as bad as the Suburu? Those things sound terrible when under load at low rpm.

 

As a devoted Subaru boxer-engine owner, I can't say as I agree at all. Like BMW-rad, Subaru is an engineer's car, the most popular car among readers of Scientific American.

 

Ben

[philbytx]

I actually agree with Ben on this !! LOL

 

As both a Subaru and BMW boxer owner,IMHO,the Subie H4 motor is a gem. Durable, dependable, easy to work on and it comfortably does everything we require from it. The motor flawlessly towed our loaded Forester (luggage/Thule) with the RT/Kendon trailer combo behind it many thousands of miles over the Sierras, Rockies and also flat out on Interstates. All the while using little to no oil and getting us anywhere from 21 to 25mpg.

 

Also, my (and my family's) life depended upon boxer motors for most of my 30 plus years as a pilot .

 

 

[AZ Pete]

Just as outdated as the piston engine for powering transportation, I would say.