Pros and Cons of owning a Boxer engine

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Hi,
andyd - Yes No 3 was the problem on early VW engines - valve stretch was the problem, due to insufficient cooling. Valve adjustments were frequently needed and "the stretch" could be picked up via this

Around 1905 Porsche developed a four cylinder boxer air cooled aircraft engine for Austro-Daimler that was very similar to the VW of 1936-7.

In his Consultancy business from 1930 he worked on projects for many Auto Companies. He worked for Auto-Union and Daimler Benz and many others - always on Contract. His credibilty was always kept intact and I would have seious doubts about the Tatra story. Tatra were well known for their aircooled rear engined V8s! They are well known today for their heavy trucks
 
Hi,
mechanicx _ I was answering the issue of Porsche "stealing" the boxer design from Tatra. Porsche was infatuated by boxer engines but he designed almost all other engine configurations too

Karl Benz did indeed Patent the boxer engine in the late 1800s. He and Maybach were "engine buddies" - Benz never cared much about the cars......! His original engine Factory still lives on as Daimler AG's engine Plant in Unterturkheim. The Mercedes Benz Museum opposite the Factory displays most of his early engine designs including a boxer. Well it was there when I was in May this year at least!
 
I remember reading about 2-stroke, opposed piston engines for use in commercial shipping a half-dozen years ago - I can't remember whether for aux machinery or MPU's. They always seemed neat, and I'm sure an air-cooled version would work very nicely in a little econobox.

I wonder how they'd tackle the emissions. The speaker's comment made it seem as if emissions were ok, but I have my doubts. Exhaust scavenging might be an issue as far as efficiency goes; however, I would think that the exhaust gasses and unburnt hydrocarbons remaining in the cylinder after the piston covers the exhaust ports would help lower emissions by lowering the flame front temp (lower NOX, but maybe higher particulates?.)


I remember when the second generation Mazda rotary came out I thought the way they tackled emissions was pretty neat. I don't remember all of the details, but the inherent problem was with original design's placement of the exhaust ports. The ports were along the outside of the chamber. The newer design moved the exhaust port closer to the center of the chamber so that exhaust would exit the port while heavier, not-fully-burned hydrocarbons would, due to centripetal force, remain along the outside of the chamber and follow into the injection/combustion portion of the cycle to be fully burned on the next "stroke." I don't know much more about it than that...

More on topic, I just got to the parent's home for the holidays, and my 97 Legacy with 202k miles averaged 26 mpg over the 250 mile drive. It was also quieter now that I stopped using MMO in the fuel
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My last extended trip in the SVX was approximately 11K miles and I averaged 28.07 mpg (almost all of it on regular) for the entire trip...

Cheers!

p.s. So much for the myth of "poor fuel economy"!
 
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Originally Posted By: JHZR2
500k is a tough thing. Though a maintained diamond in the rough from any engine class/type with maintenance can likely do 500k, very few ever do. The only engines I view as true 500k engines for passenger cars/trucks are older mb 616/617 diesels, cummins b series diesels, older Toyota 4 cyl engines, ford i6 truck engines and the older gm 350/262 engines. Most others have too many issues too early to be true 500k engines.


There are many VW TDI engines with over 500k miles, and one at least with over 900k miles. Not sure if there are any million-mile TDIs in Europe.

At over 300k miles, my Golf TDI is running better than new and I look forward to at least another 300k miles.
 
Originally Posted By: Doug Hillary
Hi,
ueberoo - The Type 3 VW was a great car. I collected a new Fastback from Wolfsburg in mid December 1966 - 43 years ago! My first new car!!!

The Type 3 engine had a horizontal fan (and much better cooling) so the whole engine package was great. Dr Porsche would have been very pleased I think!

Double boxer?

The Commer TS3 was a horizontally opposed piston, two stroke, diesel engine. Called the "Commer Knocker" it was quite popular in English trucking circles. It was popular here in NZ and Australia too with many still on the roads into the 1980s. The noise was very satisfying to many!


Hi Doug,

Another type of double boxer was the BRM H-16, really two separate flat eights from the previous 1.5 liter Formula One stacked and mated through a torsion shaft.
Many problems in actual racing applications, and I don't know that the engine ever completed an entire event.
Have to check the excellent and very witty tome by LJK Setright.
 
Originally Posted By: gathermewool
I wonder if we'd even notice that much of a change in the way the engine sounds. My 97, and to a certain extent my 08 both have a unique sound some mistake for a diesel. Well, most mistake the noise my 97 makes when cold as dying, but she's made that sound since I bought her 40k miles ago. puuuurs when warm ; )


A lot of that "Subaru sound" on turbo Subaru engines isn't related to the boxer architecture per se, but rather the unequal length headers. That lumpy Subaru sound is due to exhaust pulses being paired together.

If you put equal length headers on, the sound is much less lumpy, as the exhaust pulses are more evenly spread out.

I'm not sure if this is the case with non-turno Subaru motors, though.
 
Originally Posted By: robbobster
Originally Posted By: gathermewool
I wonder if we'd even notice that much of a change in the way the engine sounds. My 97, and to a certain extent my 08 both have a unique sound some mistake for a diesel. Well, most mistake the noise my 97 makes when cold as dying, but she's made that sound since I bought her 40k miles ago. puuuurs when warm ; )


A lot of that "Subaru sound" on turbo Subaru engines isn't related to the boxer architecture per se, but rather the unequal length headers. That lumpy Subaru sound is due to exhaust pulses being paired together.

If you put equal length headers on, the sound is much less lumpy, as the exhaust pulses are more evenly spread out.

I'm not sure if this is the case with non-turno Subaru motors, though.

I'm not sure how a header changes the sound of a Subaru turbo, but I had a friend that installed some on a WRX, and he said the power gains were almost zero.
 
IMO there is no inherent efficiency advantage or disadvantage to a boxer. I think the observed lower efficiencies are because historically a lot of boxers have been air-cooled (Chevrolet, Porsche, VW) and in modern times the liquid-cooled versions have tended to be used in applications that lower fuel economy of any engine (AWD- Subaru, high-performance- Porsche).

As mentioned, their balance is very good but not perfect. The crankshafts don't have the large counterweights of a V-type engine, but they do need small weights to counter the fact that the pistons are offset along the crank. They don't have the horrific 2nd-order "bounce" that inline 4 engines have which necessitates balance shafts in pretty much anything over 1.5 liters, so they're probably most advantageous when used as a 4-cylinder.

Their big drawback (again JMHO) is complexity. They're inherently complex to assemble because the crankcase generally has to be split to allow the crank to be installed or removed. Removable cylinder jugs are also frequently used in air-cooled applications. Overhead cams always have a tortuous chain or belt routing, pushrods are typically external if used, and rocker boxes result in a lot of oil seals and a tortuous oil return path.
 
Originally Posted By: 440Magnum

Their big drawback (again JMHO) is complexity. They're inherently complex to assemble because the crankcase generally has to be split to allow the crank to be installed or removed. Removable cylinder jugs are also frequently used in air-cooled applications. Overhead cams always have a tortuous chain or belt routing, pushrods are typically external if used, and rocker boxes result in a lot of oil seals and a tortuous oil return path.

That, and the OE has to cast 2 different cylinder heads instead of one on an inline engine.
 
As an owner of one previous NA(2.2L Legacy) Subaru and currently two turbo Subaru's(2.0L WRX & 2.5L Legacy GT) I really cannot state an advantage or disadvantage specific to the motor.

I love my two turbo engines. The 2.2L was okay.

I see timing belt as con mentioned however my the replacement cost has been less than my previous Honda and Toyota in-line's.
 
Originally Posted By: artificialist

That, and the OE has to cast 2 different cylinder heads instead of one on an inline engine.


Very true, but casting separate heads isn't a boxer issue per se...most V-type engines also need separate heads (with the exception of exceptionally narrow V's like the VW VR6).
 
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Originally Posted By: robbobster
Originally Posted By: artificialist

That, and the OE has to cast 2 different cylinder heads instead of one on an inline engine.


Very true, but casting separate heads isn't a boxer issue per se...most V-type engines also need separate heads (with the exception of exceptionally narrow V's like the VW VR6).

Sure, there are plenty of V6 and V8 engines.

The reason I mentioned it is because the majority of Subaru cars have a 4-cylinder engine, and every other 4 cylinder car is an inline.

I say this because I always think of the Subaru WRX and Mitsubishi Lancer Evolution.
 
But a lot of V8s use one *casting* for the cylinder heads. It's just flipped end-for-end depending on which side its installed on. There's no such thing as a "left" or "right" head on many v8s or v6s.
 
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Originally Posted By: JHZR2
Originally Posted By: Marukai
I would like for some of you to post some opinions about Boxer engines, also known as H engines or horizontally opposed engines. I hear that they are significantly more expensive to produce, but they last over 500k miles.


500k is a tough thing. Though a maintained diamond in the rough from any engine class/type with maintenance can likely do 500k, very few ever do. The only engines I view as true 500k engines for passenger cars/trucks are older mb 616/617 diesels, cummins b series diesels, older Toyota 4 cyl engines, ford i6 truck engines and the older gm 350/262 engines. Most others have too many issues too early to be true 500k engines.


I kinda disagree on why you're right, but your right- its a tough thing. IMO almost any American cast iron non-high-performance v8 or older inline six is capable of half a million miles, there's nothing inherent in the design that prevents it (barring plastic "silent" timing gears from the 70s). But that takes a LONG time to do for most people, and they either get tired of the car before then, it gets wrecked, or time and the elements deteriorate the body and interior to the point they stop maintaining the engine. That's even true of Cummins [censored] in non-fleet Rams that only see 15-20k miles a year, and Ford/Navistars for the same reason. I own a 437,000 mile 73 Plymouth which I've had since 1980, and I drove that car 23,000 miles a year for 10 years, ~12,000 miles a year for another number of years, and still haven't made it to 500k before I got interested in owning some other vehicles and semi-retired it. If I were in sales or something where I were on the road all the time that's the only way I could see racking up a half million miles in a reasonable time.

The only truly unusually long-lived gasoline engine that springs to my mind is the old GMC 305 v6 and its brethren. That was a true industrial engine that got put in pickups and dump trucks in the 60s.

http://www.6066gmcguy.org/305V6.htm
 
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Do all boxer engines have oil squirters? How does the oil get from the oil pan to the moving parts?
 
So far I've put about 2500 miles on my Corvair since I rebuilt it. Runs very smoothly and has averaged 21 mpg. Nothing to complain about, especially for a 3 speed with a 3.89 dif.

You do need to keep the air passages of air-cooled engines free of debris and sealed. Many people leave off the plug seals, metalwork, etc. and end up hurting the air flow and cooling.
 
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