Boxer/Flat 6 Cylinder Question

[StretchPhoto]

Greetings, all.

I've been doing a little online research about the boxer/flat 6 engine and I have a question I wonder if someone here could answer:

I know that the opposing pistons in the engine fire in such a way that they mimic two boxers' sets of gloves hitting one another in the center of a ring before a match.  However, in what order to they fire?  Do all three sets fire at the same time?  Is it 1,2,3,1,2,3 (front to back)?  1,2,3,2,1,2,3? Something else?

Also, do you know of an animated illustration online anywhere that would show the internal workings of the cylinders?

From a novice seeking enlightenment from brighter minds than mine.

Thanks!

[Patrick]

There are many various firing orders for 6 cylinders engines depending on valve/camshaft timing[ and vibration considerations.. Even flat 6 engines have various firing orders, again depending on valve, ignition considerations and cylinder number system..
Honda Valkyrie and Chevrolet Corvair, 145236
Porsche, 162435
Most Amierican in-line 6's, 153624
Many V-6's [ especially GM V-6's] have several different firing orders..

As far as watching a video,, any showing the 4 cycles/strokes will work.. All engines as pretty much the same in the respect.. The way the valve is opened/closed may be different for the engine configuration [ OHV, OHC,etc] ,, but,, the cycle/stroke are all the same..

[custom1]

A flat six. Not necessarily a Valk tho.

Flat 6 engine	powered by Aeva

[custom1]

This one is cool. Need to dub in the sound of a Valk.

Six-cylinder Boxer Engine	powered by Aeva

[StretchPhoto]

Fascinating replies, especially that vid by Patrick.

When you say "145236," where is 1 and 2?  Front left and right?

Thanks.

[gordonv]

Also, with regards to the Valk, we only have 3 coil packs. Each pack firs 2 cylinders at the same time. I think we discussed this a while ago, but one of those 2 cylinders would be at TDC waiting for the spark, and the other cylinder would be 360* (2 strocks) away at the end of the exhaust, firing on the end of the exhauts strock.

[Chrisj CMA]

On the Valkyrie engine opposing pistons are at TDC at the same time only one is on the compression stroke.  Each pair of pistons is off set by 20° or 30° or so, so the 1,2,3 punch is between pairs of cylinders.

[StretchPhoto]

On the Valkyrie engine opposing pistons are at TDC at the same time only one is on the compression stroke.  Each pair of pistons is off set by 20° or 30° or so, so the 1,2,3 punch is between pairs of cylinders.

So it's going 123, 123, 123, 123, 123...?

[gordonv]

Yes, but there are 6 cylinders, a pair of 2 firing at the same time, but only one of those pairs is on a compression strock, and the other is empty.

The next time the same pair fires, they are reveresed, the empty is now compressed, and the compressed is now empty.

Page 1-5 of the service manual, shows the Valk engine fires 1-4-5-2-3-6.

Page 17-0 (page 375) shows the 3 coils, 1-2, 3-4, & 5-6 are the pairs. Each pair/cylinder is across from each other.

[Patrick]

SP,, even cylinders are left [clutch lever ]side front[2] to rear[6].. Odd cylinders are right[throttle]side front[1] to rear[5]..

[fordmano]

Also, with regards to the Valk, we only have 3 coil packs. Each pack fires 2 cylinders at the same time. I think we discussed this a while ago, but one of those 2 cylinders would be at TDC waiting for the spark, and the other cylinder would be 360* (2 strokes) away at the end of the exhaust, firing on the end of the exhauts stroke.

I think this is referred to as a "Wasted Spark Ignition System". Where when the 2 plugs attached to the same coil fire at the same time but only 1 cylinder is prepared for a fire/power stroke at that given moment in time. Way back when,,, lots of guys would swap out the dual fire coils on a motorcycle with a single fire coil (from a car) but you would need to have twice as many coils, the theory was if memory serves is that the dual fire coil like on the Valkyrie only supplies approximately 30,000 volts but only half of that goes to each plug and  a car coil will develop more than 45,000 volts and when it fires that 45,000 volts it goes only to the spark plug that that coil is attached too although the other matching coil also fires with no effect since again that cylinder is not at the top of  fuel charged compression stroke. With the higher voltage at fire, you have more energy to jump a larger spark plug gap and this will affect your fuel charge ratio and even your timing I can’t remember the details of those items but in general this has the ability to develop a lot more power there are many other variables that can come into play compression ratio total air fuel intake and exhaust capabilities.



Well was that confusing enough for everyone? LOL! Sorry I started thinking and rambling hopefully I did not confuse the OP too much here.

[Patrick]

Waste spark ignition[ what our bikes use] is simple.. As stated, one coil fires 2 sparklers.. While one cylinder is on compression near TDC[top dead center] the coil field is collapsed which fires that sparkler, to complete the circuit the opposite sparkler[at the same exact time] fires when on its exhaust stroke which is a 'waste' of perfectly good electricity..

[StretchPhoto]

... a 'waste' of perfectly good electricity..

I see a hybrid gas/electric Valkyrie in someone's future.

[Ricky-D]

The Valkyrie motor is a strange one to try and understand.

I think the "boxer" definition is for two reasons, the first being that it is a flat motor with the pistons being opposed and the second that opposing pistons are at TDC at the same time.

The front pistons #1 & #2 are set at a 90 degree rotational crank angle to the rest of the pistons, which are all in unison and run together, meaning that the pistons #3, #4, #5, & #6 are all at TDC at the same time.

This is the reason that the motor is such a smooth running motor.

***

[Chrisj CMA]

The Valkyrie motor is a strange one to try and understand.

I think the "boxer" definition is for two reasons, the first being that it is a flat motor with the pistons being opposed and the second that opposing pistons are at TDC at the same time.

The front pistons #1 & #2 are set at a 90 degree rotational crank angle to the rest of the pistons, which are all in unison and run together, meaning that the pistons #3, #4, #5, & #6 are all at TDC at the same time.

This is the reason that the motor is such a smooth running motor.

***

if #3,4,5,6 are all the same why are there 3 timing marks.  One for 1/2 another for 3/4 and eh last for 5/6.  Makes me think all three are staggerd in pairs

[Patrick]

Our engines utilize 6 crank throws/pins in 3 pairs.. Each pair uses 2 crank pins in the same plain [ 180*],, 1/2,3/4,5/6.. Each pair is 120*/60* from each other.. This makes for a very smooth and strong engine.. Most older and less expensive designs use 2 connecting rods/pistons per crank pin[ 3 pins in a 6 cylinder engine] also set at 120* from each other which is also a smooth engine but not as much so as the 120/60 design..
By comparison, look at a simple design.. Some 2 cylinder engines use one crank pin [ 360* crank] for both cylinders, such as Harley and English motorbikes.. Do they vibrate ?? Most other manufacturers use the 180* crank for their 2 cylinder engines which uses 2 crank pins which is greatly smoother than the 360* design..
Since I don't have a degree symbol,, * will do I guess..
Clear as mud, huh ..

[Chrisj CMA]

Our engines utilize 6 crank throws/pins in 3 pairs.. Each pair uses 2 crank pins in the same plain [ 180*],, 1/2,3/4,5/6.. Each pair is 120*/60* from each other.. This makes for a very smooth and strong engine.. Most older and less expensive designs use 2 connecting rods/pistons per crank pin[ 3 pins in a 6 cylinder engine] also set at 120* from each other which is also a smooth engine but not as much so as the 120/60 design..
By comparison, look at a simple design.. Some 2 cylinder engines use one crank pin [ 360* crank] for both cylinders, such as Harley and English motorbikes.. Do they vibrate ?? Most other manufacturers use the 180* crank for their 2 cylinder engines which uses 2 crank pins which is greatly smoother than the 360* design..
Since I don't have a degree symbol,, * will do I guess..
Clear as mud, huh ..

ya, I think thats what I meant...........120° from each other (3 pairs) not one pair 90° from all the rest, that makes no sense.

BTW (alt) 2 4 8  makes a ° sign

[StretchPhoto]

As with most things, º is simpler on a Mac -

Option Zeroº

Just think of all the energy wasted on those extra keystrokes. 

[Patrick]

º,º,º..  Yep, that works !!  Its nice to learn something everyday !! Thanks.. Now all I have to do is remember it !!  I've had this Mac laptop for a year and didn't know that, well, now I do..

[Cracker Jack]

Scuse me! What a bunch of bull, especially Ricky-D. These motors are as simple as they come. The motors provide a power stroke every 120 degrees or three times per revolution. 1, 4, 5 on one round in that order and 2, 3, 6 on the next. The smoothness comes from the fact that each pair's movement is opposite of each other. They move out together, (opposite directions) and in together thereby cancelling each other's vibration.

I'm a long time lurker but could not resist speaking up on this post. I'll go back in my hole now.

[Chrisj CMA]

Scuse me! What a bunch of bull, especially Ricky-D. These motors are as simple as they come. The motors provide a power stroke every 120 degrees or three times per revolution. 1, 4, 5 on one round in that order and 2, 3, 6 on the next. The smoothness comes from the fact that each pair's movement is opposite of each other. They move out together, (opposite directions) and in together thereby cancelling each other's vibration.

I'm a long time lurker but could not resist speaking up on this post. I'll go back in my hole now.

good on ya cracker Jack.....I like a guy that calls it like he sees is..........

[Patrick]

Bull and simple, I find this interesting.. It only took almost 200 years between Huygens and Otto[ 4 cycle] / Clark [ 2 cycle] and another 130 years to get where we are today.. Internal combustion engines haven't changed much over the years, in that, the principles are the same.. How to make use of those principles has changed..

[StretchPhoto]

º,º,º..  Yep, that works !!  Its nice to learn something everyday !! Thanks.. Now all I have to do is remember it !!  I've had this Mac laptop for a year and didn't know that, well, now I do..

The one I use most of all is COMMAND/TAB, which scrolls through open applications, and COMMAND ~, which scrolls through various windows of the front app.

Lots of cool stuff here:  http://www.danrodney.com/mac/index.html

[StretchPhoto]

Scuse me! What a bunch of bull, especially Ricky-D. These motors are as simple as they come. The motors provide a power stroke every 120 degrees or three times per revolution. 1, 4, 5 on one round in that order and 2, 3, 6 on the next. The smoothness comes from the fact that each pair's movement is opposite of each other. They move out together, (opposite directions) and in together thereby cancelling each other's vibration.

I'm a long time lurker but could not resist speaking up on this post. I'll go back in my hole now.

That's the way I'd always pictured it, but I wasn't sure...

[The Anvil]

How to make use of those principles has changed..

Especially in terms of fuel delivery and timing. From the deck to the crank the internal combustion engine hasn't changed much at all in the last century, but from the deck out to the air? BIG changes. If you took an average auto mechanic from the 50's and handed him a modern multivalve engine with port injection, VVT, exhaust power valves and an ECM with more processing power than the Space Shuttles computers (which actually isn't very much) he'd crap a live squirrel.

But the Valk engine is stone simple.

[YoungPUP]

 he'd crap a live squirrel.

I'd pay to see that!!!!  How do we get a mechanic here from the 50's????

[Madmike]

Scuse me! What a bunch of bull, especially Ricky-D. These motors are as simple as they come. The motors provide a power stroke every 120 degrees or three times per revolution. 1, 4, 5 on one round in that order and 2, 3, 6 on the next. The smoothness comes from the fact that each pair's movement is opposite of each other. They move out together, (opposite directions) and in together thereby cancelling each other's vibration.

I'm a long time lurker but could not resist speaking up on this post. I'll go back in my hole now.

.... may be obvious but notice that the firing order switches sides as it progresses through the sequence ... odd, even, odd, even, odd, even ....

[Patrick]

Hey, hey, hey,, I've been mechanic-ing since the 50's and I think I'm still here..

[Patrick]

Lots of cool stuff here:  http://www.danrodney.com/mac/index.html
 
Hey Thanks, again.. Its now bookmarked and about to be printed.. Some of us old gizzards have a heck of a time figuring out these computer thingys.. Well, at least, I do..

[Ricky-D]

I can see that the self described tech savvy contributors on this thread can sure postulate on something they have no ability to defend by the same method, namely accurate description.

Not only are some not actually reading what I have stated but turning my words around to try to use my words to criticize me. Probably since this is a reflex action brought to the surface by the lower echelons of the thinking process........

I guess to start it is necessary to explain that TDC is an acronym for "Top Dead Center" which refers to the position of the piston in the cylinder related to the crankshaft/pin position for that one particular cylinder............Have you got that now, or are you going to want to argue about that?

I'm sure there will be a few that will argue that this is not correct either...................So now if you are all together in unison, please explain to me how and why:

(1) There are only two pulse generators for the three coils on the Valkyrie motor. The ignition being a CD (capacitive discharge) system means the coils need a positive trigger to make a spark. Note that the pulse generators are at a 90 degree angle from each other. There are not three pulse generators.

(2) There are thee coils. One each for two cylinders. (cyl. 1&2) (cyl. 3&4) and (cyl. 5&6)  and that the firing order of the Honda Valkyrie motor is: 1-4-5-2-3-6

Without needing to go into anymore detail for those with a little bit of automotive knowledge: You more knowledgeable ought to be able to explain pretty clearly (what you say is correct) so the others that are less educated in the automotive arts will be able to understand clearly. Not simply conjecture!

Because up to now, all the guesses are wrong!

***

[Chrisj CMA]

I can see that the self described tech savvy contributors on this thread can sure postulate on something they have no ability to defend by the same method, namely accurate description.

Not only are some not actually reading what I have stated but turning my words around to try to use my words to criticize me. Probably since this is a reflex action brought to the surface by the lower echelons of the thinking process........

I guess to start it is necessary to explain that TDC is an acronym for "Top Dead Center" which refers to the position of the piston in the cylinder related to the crankshaft/pin position for that one particular cylinder............Have you got that now, or are you going to want to argue about that?

I'm sure there will be a few that will argue that this is not correct either...................So now if you are all together in unison, please explain to me how and why:

(1) There are only two pulse generators for the three coils on the Valkyrie motor. The ignition being a CD (capacitive discharge) system means the coils need a positive trigger to make a spark. Note that the pulse generators are at a 90 degree angle from each other. There are not three pulse generators.

(2) There are thee coils. One each for two cylinders. (cyl. 1&2) (cyl. 3&4) and (cyl. 5&6)  and that the firing order of the Honda Valkyrie motor is: 1-4-5-2-3-6

Without needing to go into anymore detail for those with a little bit of automotive knowledge: You more knowledgeable ought to be able to explain pretty clearly (what you say is correct) so the others that are less educated in the automotive arts will be able to understand clearly. Not simply conjecture!

Because up to now, all the guesses are wrong!

***

Ya know ricky...........I may get sensored for this, but you can be such an A$$.  If 4 out of the six cylinders were at TDC at the same time then you could adjust two intake and two exhaust valves at two of the settings.  You cannot, you can only adjust ONE intake and ONE exhaust valve at each (3)settings (2) times around.  So all three pairs of pistons are at TDC with their pair mate but offset from their neighbor.  

So you disagree, you are allowed to be wrong (which you are), but you attack people like you are the master and we are the idiots

[BlueValk]

I'm sure there will be a few that will argue that this is not correct either...................So now if you are all together in unison, please explain to me how and why:

(1) There are only two pulse generators for the three coils on the Valkyrie motor. The ignition being a CD (capacitive discharge) system means the coils need a positive trigger to make a spark. Note that the pulse generators are at a 90 degree angle from each other. There are not three pulse generators.

(2) There are thee coils. One each for two cylinders. (cyl. 1&2) (cyl. 3&4) and (cyl. 5&6)  and that the firing order of the Honda Valkyrie motor is: 1-4-5-2-3-6


***

I am not 100% sure what your point is.  But, on my old KZ1300 (a 6 cylinder), there were 3 pick-up coils.  One for each spark coil.  And they could be adjusted individually.

The pick-up coils on our Valks are used differently.   I imagine that the missing tooth on the trigger wheel combined with the two pick-up coils tells the ICM what the timing is, so it knows which coil to fire and when.  Otherwise, it could almost work with just one pick-up coil. It does not need three pick-up coils to fire at 3 separate times.  It does that with all those teeth on the trigger/timing wheel.

Anyway, you can see on an o'scope that the three sets of coils fire 120 degrees apart from each other.

[Chrisj CMA]

I always thought one pulse generator powered one bank of cylinders and the other, the other.........either way the facts are there is only two...there are three coils, and no pair of cylinders matches another pair on TDC, they are all offset from each other.  Anyone that has adjusted valves on one of these understands that perfectly

[BlueValk]

I always thought one pulse generator powered one bank of cylinders and the other, the other........

Not picking on you, but of course, each of the three spark coils fires both banks at the same time.  

If we only had 1 pulse generator, the ICM wouldn't know which pair of cylinders to fire when the timing wheel tooth went by.  The ICM is kind of "blind" to the timing of the engine.  Somehow with that second pulse generator and that missing tooth, if figures out the timing.

Maybe someone who knows will chime in and and explain it.  I'd be curious to know exactly how it works.

[Chrisj CMA]

I always thought one pulse generator powered one bank of cylinders and the other, the other........

Not picking on you, but of course, each of the three spark coils fires both banks at the same time.  

If we only had 1 pulse generator, the ICM wouldn't know which pair of cylinders to fire when the timing wheel tooth went by.  The ICM is kind of "blind" to the timing of the engine.  Somehow with that second pulse generator and that missing tooth, if figures out the timing.

Maybe someone who knows will chime in and and explain it.  I'd be curious to know exactly how it works.

good point there......maybe each pulse generator as it picks up the signal for its perspective spark plug sends a pulse to the coil and the coil fires both sides....the next time around the same coil gets the charge from the other pulse generator for the opposite spark plug and then still fires both. 

[Bobbo]

The Valkyrie motor is a strange one to try and understand.

I think the "boxer" definition is for two reasons, the first being that it is a flat motor with the pistons being opposed and the second that opposing pistons are at TDC at the same time.

The front pistons #1 & #2 are set at a 90 degree rotational crank angle to the rest of the pistons, which are all in unison and run together, meaning that the pistons #3, #4, #5, & #6 are all at TDC at the same time.

This is the reason that the motor is such a smooth running motor.

***

Sorry, but the Valkyrie engine does not have a pair of cylinders at 90 degrees, and four cylinders with TDC at the same time.  It has three sets of opposed pistons set at 120 degrees from each other.  Chrisj CMA correctly pointed out the cam timing marks for each set are 120 degrees apart, and only one cylinder is at TDC on compression stroke at a time.

[Bobbo]

I always thought one pulse generator powered one bank of cylinders and the other, the other........

Not picking on you, but of course, each of the three spark coils fires both banks at the same time.  

If we only had 1 pulse generator, the ICM wouldn't know which pair of cylinders to fire when the timing wheel tooth went by.  The ICM is kind of "blind" to the timing of the engine.  Somehow with that second pulse generator and that missing tooth, if figures out the timing.

Maybe someone who knows will chime in and and explain it.  I'd be curious to know exactly how it works.

The ICM uses that space on the trigger wheel to synchronize the crank position to the firing order.  When it goes by, the ICM knows to reset the firing pattern.  You could get by with only one timing pickup, but many use two pickups to determine direction.  If the ICM senses the engine is spinning backwards, it will not fire the coils to eliminate reverse running.

[BlueValk]

The ICM uses that space on the trigger wheel to synchronize the crank position to the firing order.  When it goes by, the ICM knows to reset the firing pattern.  You could get by with only one timing pickup, but many use two pickups to determine direction.  If the ICM senses the engine is spinning backwards, it will not fire the coils to eliminate reverse running.

That makes sense.  Thank you   

[Patrick]

Waste spark ignition systems do not need any camshaft position information, they only use crankshaft position info.. The crankshaft gear/pulley is notched, but, one notch is always missing so the control module can locate itself.. Honda calls the 2 position sensors pulse generators.. These are incorporated into one module on most applications, Honda chooses to separate them.. On a 6 cylinder engine they are located 60º [ the º thing worked !]  apart..  60º sounds familiar doesn't it, and for good reason.. So the missing notch orients the ICM and each pulse generator generates its own signal wave to trigger and control ignition spark and advance [you also need to throw the coolant temperature into the mix]..Thats basically it, no guessing and no conjecture.. Don't ask me how the ICM handles this info cuz I don't know.. I can tell you how points ignition works,but, how the ICM knows when[or how] to send a signal to ground is beyond me..

[Patrick]

I guess there may be a question regarding the number of ' pulse generators '.. There are 2 regardless of how many cylinders the engine may have.. The control module needs the 2 signals[plus the missing notch] to figure things out..  They are just located differently [ 90º apart for 4 cylinders, etc. ].. Again, they are usually contained inside one package [with the proper spacing].. I should have included this in the above post..