Ducati.ms - The Ultimate Ducati Forum banner
  • Hey Everyone! Enter your bike HERE to be a part of this months Bike of the Month Challenge!

1 - 13 of 13 Posts

·
Registered
Joined
·
29 Posts
Discussion Starter · #1 ·
I've read several reports of the new v4 engine and its contra rotation etc but I'm puzzled to understand how with a 70 degree crank pin offset the firing intervals are as stated 0-90-290-380, It doesn't even add up to 720,to me it should be more like 90-200-90-340,if anyone can shed light on this I'd be grateful cheers!


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
57 Posts
0-70-90-160? if firing next to the other.
0-90-430-520? if one bank firing and other on exhaust.
0-70-450-520? if one cyl. firing and one cyl. on exhaust on both banks.
0-160-430-450? if the other way round.
 

·
Registered
Joined
·
3,588 Posts
Not sure, but a 20 degree overlap?

"It also has a clever “Twin Pulse” firing order. There’s a very brief pause between the first two cylinders firing and the second two cylinders lighting up. This is to create a “big bang” effect when coming out of curves and it makes the power easier to handle. "
 

·
Registered
Joined
·
274 Posts
This is from some Ducati preview:

The peculiarity lies in the rapid firing of the two cylinders on the left side and then on the right side of the motorcycle. In the timing diagram, the firings are situated at 90°, 200°, 90° and 340°. This particular firing order gives the V4 a sound that is quite similar to that of the Desmosedici MotoGP.

In practice, imagining a cycle that starts with 0°, the first cylinder of the front bank "fires", generator side, followed, after only 90° of rotation, by the rear bank cylinder on the same side. Then there is an interval during which the engine does not generate drive torque until the firings 90° from each other in the two cylinders on the clutch side. The "Twin Pulse" firing order, besides producing a unique exhaust sound unlike any other motorcycle, music to the ears of a true enthusiast, generates a type of power that was judged to be the best by the Ducati MotoGP riders as it generates important advantages at the power level and therefore the rideability of the motorcycle, especially when cornering and coming out of curves.
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #6 · (Edited)
This still doesn't explain the discrepancy ducati claim after the second firing and the interval (290*)till the third given a 70 degree offset,the numbers don't add up


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,588 Posts
I get 360 x 2 (twin cylinder x 2) = 720 in this explanation,

"the firings are situated at 90°, 200°, 90° and 340°. "

but these are not the numbers I have seen published. Source>? Not that I doubt you, these make more sense in spite of liking Hamster749's numbers. (0-70-90-160? if firing next to the other.")

Are we all saying the same thing but just different ways of expressing it? Two cranks?
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #8 · (Edited)
Ok so I figured it out I think.... both of my figures are correct but come from different points of reference,the version I understood which are the intervals in degrees as the crank rotates and Ducati's figures are from a fixed point (first cylinder firing i.e. Lh horizontal) and then taking each of the other crank pins positions in relation to where they will fire next


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
57 Posts
If 90-200-90-340 is correct (which looks like it is from wiki) that means they count on two revolutions first rev is 90-200 second rev is 90-340. (doesn't make sense to me as this 4 stroke engine needs 720 degrees to complete 4 steps but anyway...)

90 to 200 is 110 degrees apart. 200 to (the next) 90 is 250 degrees apart. Together they completes the first revolute (360)

Then 90 to 340 is 250 degrees apart. Last one 340 to (the next rev) 90 is 110 degrees apart. Together they completes the second revolute (another 360)

So we could say the firing order is 110-250-250-110 degrees apart and so on... like 110-250-250-110-110-250-250-110-110-250-250-110-110-...
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #10 ·
No the first rev is 0 then 90 then a 200 degree till next firing given the other crank pins offset at 70 degree will be next then 90 later and finally 340 to come back around to to begin again,my query was with Ducati's numbers but I figured out where the got there's from now


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
57 Posts
0 - 90 - 200 - 90 - 340 - 0 ... you got 5 firing order?

that last 340 back to 0 is only 20 degrees apart. Not sure if I got you right.
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #12 ·
No 1 fires then 90 later no 2 then 200 later no 3 then 90 is no 4 and crank rotates back around 340 to start again


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
57 Posts
That will be 90-200-90-340 firing interval.

Like 90-200-90-340-90-200-90-340-90-200-90-340-...

Numbers added up nicely, inlined with wiki. :)
 
1 - 13 of 13 Posts
Top