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firing angles on 60 degree vee twin??
NS Dev - 9/11/07 at 02:24 PM

getting myself confused yet again.

Just got the new DTA software which now fully copes with unequal vee twin engines, which is great as I'm about to order two S60 ecu's.

Question is, the ECU needs to know the coil firing angles (in terms of mechanical angle not actual angle after applying advance etc)

So, for a 60 degree twin with a single crank throw, is it 0-60 or 0-420????????????????

matt_claydon - 9/11/07 at 02:29 PM

In terms of the whole cycle I would think it should be 0 and 420 degrees. If you're only using a crank sensor (and hence wasted spark) then surely the ECU doesn't know the difference between 60 and 420 anyway?

MikeRJ - 9/11/07 at 02:30 PM

quote:
Originally posted by NS Dev
So, for a 60 degree twin with a single crank throw, is it 0-60 or 0-420????????????????


I guess it depends on which cylinder you call number one!

02GF74 - 9/11/07 at 02:32 PM

i cold probably work t his out but:

unequal V - are the rods sharing the same journal? if not, then how are they connected?

and the hase for the second cylinder - is this firing right after the first one or 1 roatitiojn of crank later? (if fact this is the same thing I thik depending whcih cylinder you call 1 and 2).

Now my brain is really hurting....

NS Dev - 9/11/07 at 02:40 PM

that's exactly my question, does it fire one then the second 60 deg later then have a ruddy great gap, or does it fire one, then miss no. 2 out, do a futher revolution, then fire no.2, then do 300 deg and fire no. 1 again??

re the wasted spark, no, its coil on plug, wasted spark would be of no use as the firing angles are no equal

NS Dev - 9/11/07 at 02:52 PM

having engaged my brain now, its got to be 0-420, 0-420 etc.

Brain can come back out of gear again now, off to collect some propane to warm the garage a little.

Canada EH! - 9/11/07 at 03:17 PM

The old I mean OLD Harley Davidsons had a single set of points and coil and fired both plugs at the same time, one on compression and one on exhaust. Hence the weird sound they made as any unburned gas in the exhasting cylinder would be ignited. You could still do this.

02GF74 - 9/11/07 at 03:30 PM

quote:
Originally posted by NS Dev
having engaged my brain now, its got to be 0-420, 0-420 etc.



surely that depends on whether the two power strokes are close to gether or 180ish degree apart? The latter would give smoother running so you would expect that to be the case but I cannot say without seeing the cam.


^^^^ wot thingy is saying about the old harleys; single coil with wasted spart could be used but the configuraion has to be 180ish - otherwise without thinking very hard, if the cycles were very close, I am pretty sure you wuld be firing combustiable mixture at the wrong time.

one set of points but you would need two lobes 60 degree apart to work them.

[Edited on 9/11/07 by 02GF74]

NS Dev - 9/11/07 at 05:11 PM

quote:
Originally posted by 02GF74
quote:
Originally posted by NS Dev
having engaged my brain now, its got to be 0-420, 0-420 etc.



surely that depends on whether the two power strokes are close to gether or 180ish degree apart? The latter would give smoother running so you would expect that to be the case but I cannot say without seeing the cam.


^^^^ wot thingy is saying about the old harleys; single coil with wasted spart could be used but the configuraion has to be 180ish - otherwise without thinking very hard, if the cycles were very close, I am pretty sure you wuld be firing combustiable mixture at the wrong time.

one set of points but you would need two lobes 60 degree apart to work them.

[Edited on 9/11/07 by 02GF74]


not sure what you mean.

On the aprilia, as far as I can see, it fires no 1 pot, then rotates 360 deg PLUS the vee angle (60 deg) then fires no. 2 pot, then it rotates 360 MINUS the vee angle and fires no. 1 pot again, so you get an alternating 420 and 300 crank degrees between ignition events, or as the ECU sees it, 0 deg and 420 deg in every 720 degree cycle (which is sent to the ecu by the cam phase sensor timing)

sebastiaan - 9/11/07 at 05:27 PM

take the inlet or exhaust off and look if the valve timing is 60 or 420 degrees apart....

NS Dev - 9/11/07 at 08:20 PM

indeed!

Will have a look when I'm back in the garage (which at the moment depends on when I get a new heater! )

need some fandango tool just to turn the bugger over but will ave a look asap.