[RM2488]

1. Most 4-cylinder engines (Whether Inline or Boxers) have opposite pistons and the middle pistons moving together in pairs. So cylinders 1 and 4 will go for compression/exhaust while 2 and 3 are moving towards intake/power. Therefore the famous even firing order 1-3-4-2. So no firing on opposite banks. It would make for a very clattery engine with only four cylinders!

2. The better balance on a Boxer engine is for a simple reason- opposing pistons reach Top Dead Center at the same time, canceling each other almost perfectly. Unlike the Inline 4, which requires a balancer or weights to do the same. Even though the opposing pistons on an Inline 4 still move in opposing directions, the asymmetric motion of the connecting rods leads to second order vibration and harshness. The boxer-4 has a different problem though- the opposing cylinders are not exactly in the same plane- they are on parallel planes. Therefore, they do not balance each other perfectly and there is still some vibration, but on a much smaller scale.

Personally, I find the best internal combustion engine would have to be a 12-cylinder with direct injection. Very smooth, and with the right design, it requires no starter motor because one of the cylinders is always on the power stroke. Simply inject and ignite!

[FlatOut]

Originally Posted by RM2488

1. Most 4-cylinder engines (Whether Inline or Boxers) have opposite pistons and the middle pistons moving together in pairs. So cylinders 1 and 4 will go for compression/exhaust while 2 and 3 are moving towards intake/power. Therefore the famous even firing order 1-3-4-2. So no firing on opposite banks. It would make for a very clattery engine with only four cylinders!

2. The better balance on a Boxer engine is for a simple reason- opposing pistons reach Top Dead Center at the same time, canceling each other almost perfectly. Unlike the Inline 4, which requires a balancer or weights to do the same. Even though the opposing pistons on an Inline 4 still move in opposing directions, the asymmetric motion of the connecting rods leads to second order vibration and harshness. The boxer-4 has a different problem though- the opposing cylinders are not exactly in the same plane- they are on parallel planes. Therefore, they do not balance each other perfectly and there is still some vibration, but on a much smaller scale.

Personally, I find the best internal combustion engine would have to be a 12-cylinder with direct injection. Very smooth, and with the right design, it requires no starter motor because one of the cylinders is always on the power stroke. Simply inject and ignite!

That is a very nicely put, rational description RM2488. Having had a twelve cylinder Jaguar (V12), I can safely say the engine was as close to silent as an ICE can be - there was little to suggest there was actually an engine under the bonnet, except for the rapid rate at which the horizon would approach. The loudest sound was the rustle of bank notes/ripping out of cheques which were constantly required if the engine were to keep firing!

Originally designed as a racing unit in the mid 1950s (modified to single cams and softer valve springs for production), it was very tough and reliable, many examples easily running past 300,000 miles with no work required at all.

http://www.youtube.com/watch?v=q-zMOqQraN8

[Jeroen]

Originally Posted by FlatOut

J and S, are you really suggesting you struggle to understand that this type of engine is better balanced than inline engines? If you think I am about to copy and paste a load of mathematical equations and university theses on this then think again! Go out there and find out for yourselves, if you have to plough through the mathematics then I am surprised - is the concept so difficult to understand?

I don't think either of us struggles, but your answer, or rather lack off, makes everything perfectly clear.

Originally Posted by RM2488

Very smooth, and with the right design, it requires no starter motor because one of the cylinders is always on the power stroke. Simply inject and ignite!

So, an engine that would start without a starter motor? Now that would be great news! So if this engine was shut down, all you have to do is inject fuel, it will ignite and start? Truly amazing!

Jeroen

[Sutripta]

Originally Posted by FlatOut

If you think I am about to copy and paste a load of mathematical equations and university theses on this then think again! Go out there and find out for yourselves, if you have to plough through the mathematics then I am surprised - is the concept so difficult to understand?

The mathematics/ mechanics of engine engine balance was worked out in quite a bit of detail (i's dotted and t's crossed) more than a hundred years ago. And Lanchaster's solution to balancing, which in some form or another is still used today, is also more than a hundred years old. And all this is there in any text, if anyone cares to look. So no, you don't have to copy and paste!

So do I think boxers are rough? What do you think after reading

Originally Posted by Sutripta

Though I like the mechanical balance of the boxers, detail development (esp mounting methods which mask out the vibrations, and advances in NVH control) mean that the extra cost of a boxer is really not justfied. Low CG - tilt the inline.

So what is it that I'm objecting to? Certainly not engine designs. Please note that my last post was a question about your interpretation of mechanics/ physics. To which we have not yet got a reply. (Could it be because there can be no reply? Let me say that you and I have very different engineering ideas.)

In my opinion, you present every opinion of yours (and you have a whole lot of them) as fact. And don't take well to someone having a different opinion.

Opinions are great. They make for interesting reading. I read some newspapers for its opinions, not news. But note what good newspapers do. They very clearly demarcate between what is news (fact) and what is opinion (the editorials and Op-eds).

There are a multitude of statements made in this forum to which I do not agree to in some degree or another. Most I just ignore. So why did I spend time on this particular thread? It is because, for a variety of reasons, you will be seen as an authority on whatever you say. In which case you should be more responsible in separating fact from opinion. (Somehow, I don't think that is going to happen.) Or somebody can put up a contrary point of view, a warning flag if you will. Not just for this thread, but for all your posts. Which is what I and some others have done. And I think that work is over. So no more posts from me on this account.

Originally Posted by FlatOut

Not some rather anal attack on one particular type of engine by a couple of lone forum members.

Nice and terse! But what happened to your command over language, your ability to post paragraphs over simple points.

Regards
Sutripta

Originally Posted by Jeroen

So, an engine that would start without a starter motor?

Used to be a party trick for some older RRs.

Regards
Sutripta

[Jeroen]

Originally Posted by Sutripta

Used to be a party trick for some older RRs.

Neat trick! I would have thought that you would still need the adiabatic heating due to compression before you would get any proper vaporization and subsequent ignition?

Also, how do you figure out which piston is at its beginning of the piston stroke? Under normal operation the injection would have started already? So you need a few gadget and electronics to figure that out too. At least I assume the firing sequence to start an engine this way, is somehow of compared to the normal firing when running? (It's later, I assume?)

Would be interesting to see some more of it.

Jeroen

[RM2488]

Originally Posted by Jeroen

Neat trick! I would have thought that you would still need the adiabatic heating due to compression before you would get any proper vaporization and subsequent ignition?

Also, how do you figure out which piston is at its beginning of the piston stroke? Under normal operation the injection would have started already? So you need a few gadget and electronics to figure that out too. At least I assume the firing sequence to start an engine this way, is somehow of compared to the normal firing when running? (It's later, I assume?)

Would be interesting to see some more of it.

Jeroen

The way it generally works is that the injection takes place at the end of the intake stroke, just prior to ignition. So the injection will not necessarily have started. And even if it has, there are multiple pistons going towards compression. So simply pick a different cylinder! And yes, the ECU in such a car will have to be pretty sophisticated- knowing exactly where each piston is.

The heating by compression isn't necessary for ignition, at least for petrol, since it will readily ignite without it. This comes at a loss of efficiency for a couple of power strokes. But the savings are huge since you can switch off the engine for longer periods of time. Additionally, the ability to burn leaner also adds efficiency. And the lack of balancing requirement for a V12 (Essentially two straight sixes) makes it even more efficient. Add to it that there are two power strokes for every rotation.

Look up "Direct fuel injection" for more info. It's fascinating!

[Sutripta]

Originally Posted by Sutripta

Used to be a party trick for some older RRs.

Party trick. (Maybe even an urban legend.) Certainly not for real world use.

Regards
Sutripta

[Jeroen]

Originally Posted by Sutripta

Party trick. (Maybe even an urban legend.) Certainly not for real world use.

Regards
Sutripta

Thought so. The other thing to remember; when an engine sits idle the compressed air will leak away eventually. That means there is a very small volume of air left, ie very few air molecules, compared to when it was compressed. How much fuel can you inject in this (cold) air and still successfully ignite? Can't be much. The more cilinder, typically will means more torque required to get it started. Initially there is more mass to get going, more friction in more bearings and there are more piston in (a part) compression stroke.

This could maybe work if the engine was still warm, was shut down for literally a few seconds and then with some clever resetting of the ignition and injection timing it might fire. Who knows.

Mind you, I have seen engines do some odd things though.

I guess we chalk this one up as "myth busted" until proven otherwise.

Jeroen

[Sutripta]

Originally Posted by Jeroen

This could maybe work if the engine was still warm, was shut down for literally a few seconds and then with some clever resetting of the ignition and injection timing it might fire. Who knows.

ECUs? Don't think there are any engines with absolute crank/ cam encoders. Question then is - why not?

Regards
Sutripta

[RM2488]

Originally Posted by Jeroen

Thought so. The other thing to remember; when an engine sits idle the compressed air will leak away eventually. That means there is a very small volume of air left, ie very few air molecules, compared to when it was compressed. How much fuel can you inject in this (cold) air and still successfully ignite? Can't be much. The more cilinder, typically will means more torque required to get it started. Initially there is more mass to get going, more friction in more bearings and there are more piston in (a part) compression stroke.

This could maybe work if the engine was still warm, was shut down for literally a few seconds and then with some clever resetting of the ignition and injection timing it might fire. Who knows.

Mind you, I have seen engines do some odd things though.

I guess we chalk this one up as "myth busted" until proven otherwise.

Jeroen

Again, see the direct injection system. The one I read up on- by Ford- although they never stated outright it had no starter motor, they did mention the direct engine start at traffic lights. So yes, it may not be entirely starter-less for cold starts. But it certainly works for warm starts.
More info: http://blogs.howstuffworks.com/2010/...-hybrid-drive/
Near the very end of the page the starter-less system is briefly described.

Originally Posted by Sutripta

ECUs? Don't think there are any engines with absolute crank/ cam encoders. Question then is - why not?

Regards
Sutripta

This system would require it, therefore it must be present in an engine with such a starting capability. The "why not" part is probably because it is hardly useful with port injection.

I see this as a natural evolution of the engine- first they mixed fuel-air before the intake manifold in a carb. Then they used injectors on ports. Now the injector sits directly in the head where you need fuel. Perfect control!

[Jeroen]

So I checked Bosch direct start and here's what I found:

http://www.bosch-automotivetechnolog...tion_1481.html

Or in some more detail:

http://www.etas.com/data/RealTimes_2...6_01_34_en.pdf

As I thought, it requires some fancy sensor techniques to figure out the position of the crankshaft and the engine needs to be warm.

Also, its not necessarily limited to V-12's only. Having said that, I'm not aware of any real life application yet. I guess there must be some, this is 2007 technology.

Jeroen

[FlatOut]

Read my opening post again, this thread was not intended to be a discourse solely on boxer engines – just one paragraph in twelve mentioned their superior balance and other characteristics. I was attempting to point out that as the internal combustion engine of the motor car gets older, it has not necessarily become more refined, rather it has been engineered to be as cheap to produce as possible, with a sufficient amount of refinement (aided by much sound proofing and vibration-absorbing mounts) to keep the public from demanding better. But that for those interested in different engines, the inline four or V6 isn’t the limit of human achievement. Money is invested where the profit returns are greatest and as pointed out, the cost of a boxer engine doesn’t necessarily justify its use.

I’m sorry you have decided to remove yourself, Sutripta. I see this forum as one for the English word and recounting real-world experience, rather than one written and explained in physics or maths. It is intended for everyone, not solely for those with a ready understanding of high-level physics, maths and engineering. I write for everyone on here, not just those with maths or physics degrees.

The motor car and its engines however are all engineering, physics, maths and other science - as well as a little bit of art – but motoring is all about the interaction of human with machine. This is what Team-BHP has to say: “Here... honest reviews, news, opinions and analysis. Team-BHP began as an inchoate dream of a handful of motorheads who live by their passion for cars.” I firmly believe that the seat of the pants is a better judge than pages of equations and sums – if this weren’t the case then there would be no need for test drivers. We are all different, so will all appreciate different aspects of design.

I didn’t give a detailed mathematical explanation for the superiority of a boxer engine since the debate is, in my opinion, more complex than just the primary and secondary forces and the use of balancer shafts to cancel these out. Equally, I didn’t attempt to give a mathematical explanation for my suggestion that varying forces pushing down on the piston may add to the imbalance of some engines, the maths would be horrendously complex. It would also have taken a day at least to brush up on my physics and read all the relevant papers, then regurgitate it on here. As you say, it is all out there online for those prepared to do the donkey work.
This lack of maths explanation obviously upset both yourself and Jeroen. You seem more concerned with the fact that I have opinions which you don’t appreciate and that I don’t dance to your demands for mathematical explanations. Your own words suggest that your issue with all this is not that boxer engines are of superior design in terms of balance, but that you disagreed with my interpretation of some of the physics. Your question did receive a reply, but not in maths.

Sutripra:
“So what is it that I'm objecting to? Certainly not engine designs. Please note that my last post was a question about your interpretation of mechanics/ physics. To which we have not yet got a reply. (Could it be because there can be no reply? Let me say that you and I have very different engineering ideas.)”

"In my opinion, you present every opinion of yours (and you have a whole lot of them) as fact. And don't take well to someone having a different opinion."

You're utterly and completely wrong with your second statement above, I love people to have opinions which are as robust as my own, then there can be some good debate had – if they can argue their point, in English. On a motoring forum I prefer the debate in English, not Maths. But when a general engine thread such as this is peppered with requests for high level mathematical proofs (when you yourself acknowledge the fact inherent superior balance of a boxer engine) and comparisons of 150mph Jaguars with pre-war rustic peoples’ cars in an attempt to justify quality of engine configuration then I start to feel as if the thread is deliberately being disrupted for its own sake, because you find my words not to your own taste.

Sutripta:
“Nice and terse! But what happened to your command over language, your ability to post paragraphs over simple points.”

Your sarcasm here appears to point to your objection of my use of a certain word. And possibly a difference in culture between England and India? The word I assume you are referring to is quite acceptable in everyday English, in Britain, and I didn’t use it gratuitously. If I am right about this, then I don’t imagine you can bear to watch ‘Top Gear’!
I also will make the point that describing something with maths and physics formulæ and models does not give to whole picture, since things are simplified to make it easier and to give the essence of the situation. Human hearing and feel is, if at all educated, able to pick up aspects which figures do not – a tiny vibration or a particularly quiet sound may become hugely irritating and tiring after many hours at the wheel. I have driven the smoothest ‘ordinary’ engines and find that they tire much more than a boxer over a day’s driving, especially if this is at speed. I myself find the difference quite extraordinary, which is why I bothered mentioning it in the first place. Rather wish I hadn’t bothered, now!


Here are a few quotes, which seem to support my opnions on boxer engines as fact:

http://www.e31.net/engines_e.html - good diagrams as well as text

http://www.autozine.org/technical_sc...ne/smooth2.htm
Referring to the inline four: “What about the resultant upward / downward vibration ? It seems that the movement of piston 1 is counter balanced by piston 2, while piston 3 counters piston 4. However, this is just skin-deep. More professional speaking, that just proves the balance of 1st order force. The second order force (which can be derived from equation) is normally much smaller than the 1st order force and it is rotating at twice the frequency of the 1st order force. Nevertheless, the configuration of inline-4 actually multiplies the magnitude of 2nd order force thus making it hard to be ignored, especially is for larger engines.
All boxer engines, regardless of no. of cylinders, provide perfect balance because the movement of a piston is exactly counter by the corresponding piston in another bank. However, they are too wide for good packaging, and is more expensive due to more parts used, thus the usage is limited to Porsche and Subaru today.

[RM2488]

Originally Posted by FlatOut

All boxer engines, regardless of no. of cylinders, provide perfect balance because the movement of a piston is exactly counter by the corresponding piston in another bank. However, they are too wide for good packaging, and is more expensive due to more parts used, thus the usage is limited to Porsche and Subaru today.

Not true. A boxer with 3, 5, or 7 cylinders would not be balanced naturally. And it is not all about which DIRECTION the piston is moving. An inline-6 is perfectly balanced as well. Your up-and-down motion theory does not then hold water.

I'd pick an inline-6 over a boxer-4 any day- 'cause any old mechanic could fix it. Now THAT is good design- traditionalist, but with innovation. Taking one kind of design to perfection.

[FlatOut]

Originally Posted by RM2488

Not true. A boxer with 3, 5, or 7 cylinders would not be balanced naturally. And it is not all about which DIRECTION the piston is moving. An inline-6 is perfectly balanced as well. Your up-and-down motion theory does not then hold water.

I'd pick an inline-6 over a boxer-4 any day- 'cause any old mechanic could fix it. Now THAT is good design- traditionalist, but with innovation. Taking one kind of design to perfection.

The quote you label as mine, RM2488, is from autozine.org's technical section. I thought someone may pick up on the rather slack and sloppy use of English. Did you really think they were suggesting the possibility of a boxer with an odd number of cylinders? It's rather like suggesting a car with three wheel drive.

I agree with your comment regarding mechanics, although engines have always been the most reliable component of my cars - and I use them hard. The only time they are worked on is for a cambelt change, when there is such a horrible thing connecting the shafts. I'm interested that in India they often seem to be pulled apart, needing rebuilds - from what I read on here. I know of mechanics who refuse to work on certain Renaults (with I4 engines) because of accessibility problems under the bonnet. I'm not sure how your 'innovation' comment is relative to the I6.

My Mercedes diesel has the most gorgeous six in a row and is one of the all-time great diesel engines in my book. But this layout has steadily been vanishing for packaging amongst other reasons - they are long, tall engines which tend to lead to a lot of weight in the nose of the car, BMW (one of the few makers persevering with the I6) has gone to massive efforts to try and avoid this. A V6 is torsionally stiffer, is cheaper to make, takes up less room and seems to be steadily replacing its inline cousin.

VW's VR6 (vee reihen = inline vee with its Lancia-inspired narrow angle vee with just one cylinder head) and its progeny are interesting engines - seemingly many of the benefits of an inline 6, few of the drawbacks of a V6 and possibly cheaper to make than either. Putting two of these narrow-angle VRs into a traditional V makes for very interesting engines - anyone got one?

Here is a new design of engine, going into production shortly. Does anyone recognise it?

[RM2488]

Originally Posted by FlatOut

The quote you label as mine, RM2488, is from autozine.org's technical section. I thought someone may pick up on the rather slack and sloppy use of English. Did you really think they were suggesting the possibility of a boxer with an odd number of cylinders? It's rather like suggesting a car with three wheel drive.

Nothing is impossible- three cylinder inlines were common enough at one point- the venerable M800 having one. So it appeared as a possibility- perhaps they should have stated all boxer pairs are balanced.

Originally Posted by FlatOut

I agree with your comment regarding mechanics, although engines have always been the most reliable component of my cars - and I use them hard. The only time they are worked on is for a cambelt change, when there is such a horrible thing connecting the shafts. I'm interested that in India they often seem to be pulled apart, needing rebuilds - from what I read on here. I know of mechanics who refuse to work on certain Renaults (with I4 engines) because of accessibility problems under the bonnet. I'm not sure how your 'innovation' comment is relative to the I6.

The rebuild necessity is a culmination of many things- poor maintenance(including the service centers), horrible driving techniques, long periods of idling in traffic, poor quality of fuel and other consumables, manufacturers cutting corners for economy/corruption... and probably a lot more. The innovation comment was for the fact it was an inline- traditional- but managed in such a way that it requires no balancing- innovation.

Regarding accessibility- I love the spacious engine bay in my Ikon. But practically every car on the market is so jam packed now- remove ten things for a single component. Although it probably makes the car more efficient, but difficult to work on for DIYers like me.

Originally Posted by FlatOut

Here is a new design of engine, going into production shortly. Does anyone recognise it?

Looks like an evolved opposed piston engine. The "Commer Knocker" TS3 had an opposed piston with a gorgeous sound. Must look this one up.