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Harley
Dropped
Joined: 26 Nov 2007
Posts: 394
Location: Braidwood - Australia
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 Posted: Thu Sep 23, 2010 3:15 am Post subject: Twinspark ignition |
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Megasquirt guru's needed;)
I plan on running Twinspark on my new engine, Megasquirt spark control.
The setup i am considering (never done any ignition control b4....);
- Sequential ignition (because of supercharger), Coil on plug using 2 yellow Harley coils to fire both plugs in one cylinder head at a time (similar to 4cylinder wasted spark setup).
- 60-2 trigger wheel at the cam, with VR sensor.
I have been reading up on the Dual-spark code.
M-N Cam Wheel Only This option provides for a cam driven M-N wheel (1 input) which gives 2 cyl COP.
Is this the correct route for me to take?
I currently have an MS-1 controller so will upgrade to either a MS-2 or MS-3 cpu first...
My modified cylinder heads.
Cheers
Harley
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Malte
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Joined: 11 Dec 2007
Posts: 534
Location: Germany
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| Posted: Thu Sep 23, 2010 12:25 pm Post subject: |
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great idea!
i think cumbustion should get much better with 2 sparks!
another interesting theory:
fire 2 times but one time afer another.
Ignitions Boxes like MSD AL6 do that up to 2500rpm(8zylinder).
looking forward to hearing if it works better! :)
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huub
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Joined: 06 Jan 2009
Posts: 2
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| Posted: Sun Oct 03, 2010 6:39 pm Post subject: |
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nice job , make sure you check for claerance with the piston.
the firts time i fitted a second plug to a 2cv engine i had also raised the cr by shortening the cylinder.
i ended up shaving a bit off the piston to get it to work.
i had good results calculating the advance for the new setup by simply using the speed of sound as the speed of the flame front.
not perfect, but good enough for me.... |
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Harley
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Joined: 26 Nov 2007
Posts: 394
Location: Braidwood - Australia
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| Posted: Mon Oct 04, 2010 3:21 am Post subject: |
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| huub wrote: | nice job , make sure you check for claerance with the piston.
the firts time i fitted a second plug to a 2cv engine i had also raised the cr by shortening the cylinder.
i ended up shaving a bit off the piston to get it to work. |
Yes i am concerned that the Valves may get close on my pistons;
I will turn it over by hand to check it first, my compression ratio is still 9:1 so i may add a thicker gasket at the base of the barrel to drop it to 8.5:1.
Thx for that info Malte i will research the twinspark ignition a bit more.
Harley
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Joolz
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Joined: 07 Apr 2008
Posts: 33
Location: Pays de Galles/Charente
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| Posted: Sun Dec 05, 2010 1:07 am Post subject: Re: Twinspark ignition |
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Harley, why do you think that it's important to have sequential ignition with a supercharger?
| Harley wrote: | | - Sequential ignition (because of supercharger) |
What would be wrong with keeping the wasted spark system, and firing all four plugs at once? You are upgrading to the MSII processor for the new engine aren't you? Can the megasquirt handle two coils running from the same output?
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Jasu
Dropped
Joined: 30 Sep 2007
Posts: 211
Location: Finland
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| Posted: Sun Dec 05, 2010 3:43 pm Post subject: |
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http://jbperf.com/sequential/index.html#v3conn
Does this help..?
I'm making with this JBPerformance additional injector driver semi-sequential injection and oddffire spark control to my SM, but I don't yet tried this because my MS2 processor isn't arrived...
But why You need this, will there be spark when inlet valve is still open "at other side" or what..?
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Harley
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Joined: 26 Nov 2007
Posts: 394
Location: Braidwood - Australia
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| Posted: Mon Dec 06, 2010 12:54 am Post subject: Re: Twinspark ignition |
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| Joolz wrote: | Harley, why do you think that it's important to have sequential ignition with a supercharger?
| Harley wrote: | | - Sequential ignition (because of supercharger) |
What would be wrong with keeping the wasted spark system, and firing all four plugs at once? You are upgrading to the MSII processor for the new engine aren't you? Can the megasquirt handle two coils running from the same output? |
Hey Joolz,
In the research i have done the consensus is to avoid wasted spark as it greatly increases the chance of a backfire. With a stock cam and sequential fuel injection it is not so much of an issue, I have a high-lift cam and currently non-sequential injection.
This is how i am thinking of setting up the ignition timing, it will also allow me to do sequential injection if required.
Or perhaps this way is simpler for me
@ Jasu: thanks i'll have a look at that.
Cheers
Harley
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Spot my 2cv www.youtube.com/watch?v=Zoq68CPLq4M |
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Joolz
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Joined: 07 Apr 2008
Posts: 33
Location: Pays de Galles/Charente
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| Posted: Mon Dec 06, 2010 2:26 am Post subject: |
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Okay, I see how it could be a problem if you have a cam that opens the inlet valve earlier. So I won't worry about it with a standard engine. I looked at that dual spark page before,  .
The be-em engine has twin plug heads as standard, but if all four fire together I don't know if dual spark is necessary, it probably wouldn't be easy to add a cam sensor. It's not a big issue, I could run it on two plugs if I had to.
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