MSD Ignition
#26 _hardrevin'_
Posted 20 February 2006 - 06:56 AM
#27
Posted 20 February 2006 - 12:31 PM
To make it clear, Multi Spark Discharge systems are called MSDs. "MSD ignition" to me means any multi spark ignition system, whoever makes it, just like 'radial tyre' means a radial tyre, not a Bridgestone or a Dunlop tyre.
To clarify things more, or maybe confuse them more, the MSD (brand name this time) ignitions manufactured by Autotronics aren't all MSDs - the base model at least, which is still sold as a MSD branded unit is not an MSD. It's also only the top of the range MSD (brand) ignitions which are both MSD and CDI units combined.
#28
Posted 21 February 2006 - 02:54 AM
The term 'MSD' is confusing. Dangerous IS CORRECT when he says not all Autotronic MSD ignitions are Multiple Spark, some are just CD ignitions (like the MSD Blaster Ignition) but the majority of Autotronic MSD ignition systems are a combination of Multiple Spark and CD ignitions (and not just the top end of the range systems either).
I don't know of any ignition systems manufactured today that are just Multiple Spark. I'm not saying they don't exist, just that I don't know of any.
Speaking of combining things... I had a chocolate flavour beer from Belgium the other day, a Floris Chocolat. It was quite unusual, it smells like chocolate, tastes like chocolate but I woke up the next day with a terrible hangover!
So try combining a Freddo with a VB when you get a chance Hardrevin'!
#29 _brett_32i_
Posted 06 March 2006 - 08:13 PM
they actually have the cdi kit still available k-3307.
i want to build one up to run with my rb30t.
#30
Posted 07 March 2006 - 01:53 PM
#31 _brett_32i_
Posted 10 March 2006 - 12:17 PM
who? me?Bang for buck and reliability wise, have you considered using the later RB series or VG series power transistor unit (PTU) and the Z32 VG series direct fire coils, ie one coil per cylinder?
would it not be a nightmare to hook up a multi coil system to a single coil ecu?
#32 _Eddie_
Posted 20 March 2006 - 09:09 PM
Now I can understand why it would be advantageous to have a more POWERFUL spark inside the chamber. More power = more heat, more energy to set off an explosion inside an small area in a chamber. I understand this far. So the gain you get is a more rapid, responsive explosion (because more energy in the spark, the quicker everything explodes). Also, now because everything is exploding quicker, this actually creates a bigger explosion because it's all happening at once. Like compressing gun powder into a chamber compared to spreading it out sparsely across a floor. Or like shoving 5 durries in your mouth compared to just smoking 1.
Ok I got this far, but where's the gain of Multiple sparks come in? I mean, once the chamber explodes, it can't explode any more can it? It goes bang and thats it. It's over pretty quickly. And they only need to spark at one particular time, all other times are useless coz the pistons got to do 3 other strokes. I dunno, somebody clarify here, me no understand. Unless the spark plugs set off a short series of extremely quickly sparks at the inital process of detonation? This may create a more powerful explosion??
#33 _Eddie_
Posted 20 March 2006 - 09:18 PM
What you would gain out of it?
When you would/would not benefit from it?
#34
Posted 21 March 2006 - 02:04 PM
First up, spark power. The job of the spark is to ignite the fuel/air mixture around the spark plug, so that the flame front (the outside of the burning ball of fuel/air mix) expands at just the right time to hit the piston when it's at top dead centre with enough force to push it down again. The spark does not cause all of the fuel/air mixture to explode at once - it starts small, around the spark, then spreads in a ball shape until all of the fuel/air is ignited.
If the spark is too early, the flame front (explosive 'ball' of combustion pressure) hits the piston before it's near top dead centre, wasting some energy, and causing knock. If the spark is too late, the piston is already starting to travel down again, so the combustion pressure can't transfer as much energy to the piston, with a resulting loss of power.
There can be a problem with too much energy in the spark, where the spark actually pushes some of the fuel/air mixture away from it, instead of igniting it properly - a bit like if you try to explode too much TNT - some of it will detonate, but some unexploded chunks of TNT will be thrown outwards by the large force of the explosion.
Multiple sparks. On a standard ignition system, the single spark is quite capable of reliably igniting the fuel/air mixture. If you up the power of the engine by quite a bit though, by putting in lumpier cam, larger valves, more fuel, turbocharging etc, the fuel/air mix becomes more dense, and more turbulent. The dense fuel/air mixture is harder to ignite, and the increased turbulence can actually 'blow' the single spark out, just like blowing out a candle. Once it does this, the mixture cannot ignite, and a misfire occurs. By making the sparks multiple short sparks, if one gets blown out, it is replaced almost immediately by another one, so the mixture is still ignited. A multi-spark ignition system simply has a large number of smaller and shorter sparks in the same time period as a conventional system has one spark.
Hope that answers your qustions from post # 1
As for when you need upgraded ignition systems, that's got to be taken on a case by case instance, as it depends on how many of what type of mods you are making for an engine. As a very rough guide, if you are starting to experience misfires at the rev range where your engine seems to want to make most power, then you may have an issue with sparks breaking down.
Talking Holden 6s and 8s, in my opinion (and it's only mine, others will no doubt differ), the stock Commodore style electronic ignition systems are a good improvement for anything from standard motors all the way up to 'barely streetable', or where peak power is starting to be made around 4000 rpm and upwards. Usually at this point, the coils aren't big enough to supply strong spark at the increased redline. If you're using the car for drags as well as street, where you're obviously hitting the redline more, you might have more of a need to upgrade coil and/or ignition sooner, and seriously start to think about better plugs and leads.
#35 _brett_32i_
Posted 21 March 2006 - 07:12 PM
please more info....
#36 _brett_32i_
Posted 23 March 2006 - 07:44 PM
150 to 200 bucks.
im not sure, but they say only 2 sparks per cylinder after 3k rpm.
is this true of all cdi's?? or just this cheap one?
#37 _brett_32i_
Posted 23 March 2006 - 07:45 PM
150 to 200 bucks.
im not sure, but they say only 2 sparks per cylinder after 3k rpm.
is this true of all cdi's?? or just this cheap one?
#38 _Torana482HP_
Posted 24 March 2006 - 06:02 PM
#39 _brett_32i_
Posted 24 March 2006 - 08:32 PM
guess i pay ignition developments a call....
#40 _brett_32i_
Posted 25 March 2006 - 12:36 PM
and the pro 10 by m&w ignitions isnt multispark at all. he reckons not necessary, v8 supercars dont use it either. just single spark cdi.
#41
Posted 25 March 2006 - 02:27 PM
CDI (Capacitive Discarge Ignition) is basically an amplifier for teh spark. Bigger brighter spark. Over 3000Rpm, you dont have time for more than one spark, but the bigger brighter spark from both the CDI and MSD systems are what makes them worthwhile!
Cheers mate.
#42 _brett_32i_
Posted 25 March 2006 - 04:36 PM
#43 _Torana482HP_
Posted 25 March 2006 - 05:21 PM
but the bigger brighter spark from both the CDI and MSD systems are what makes them worthwhile!
Plus you know that when your V8's revvin at 8000, you know you will have a good spark there.
#44 _brett_32i_
Posted 27 March 2006 - 07:48 PM
#45 _dave720gtr_
Posted 27 March 2006 - 08:03 PM
#46 _Torana482HP_
Posted 27 March 2006 - 08:14 PM
looks like crane hi-6 is the go...$300 brand new
Just remember, with the crane Hi-6, you need to get the right one for your application, they are not universal like MSD (eg. why type of dizzy your using etc.) so if your getting one of ebay make sure its the one you need. Download the instruction manuals for the Hi-6 range off the crane website to find out which one is right for you.
when using the Hi-6 with a l-92 coil they have the highest output but they lack the features of a MSD digital 6, although a digital 6 was probably more than you wanted to spend.
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