Have recieved a heap of vw motor bits of a mate and one has had the head machined to fit a second spark plug. Just a quick question would a 009 create enough spark to run off of one lead or is a different way. Would it create much more power or not have enough drive for two.
Revmaster in the US modify heads like that for the aircraft market - It uses two coils per cylinder and a CDI that is crank fired all mounted where the flywheel once would have been...
Not practical for a street vehicle in that format, I would guess that you would want a disi with 8 outlets and a rotor that hits 2 points simultaneously, and a high voltage ignition system ???
Nah dude, you cannot fire both plugs with one coil.
You will need to set up a dual fired system with 4 twin output coils.
It is acceptable to trigger both coils from the one trigger arrangement.
A simple method of twin triggering is to set up a dizzy points plate with 2 sets of points mounted at 90 deg to each other and grind off 2 opposing lobes of the cam so each set of points opens alternately.
One set of points is fixed on the points plate and the other needs to be mad adjustable on the points plate.
This makes it easy to set the fixed points/timing first and then set the second set.
However, the points strategy is fraught with hassles such as timing scatter if the points are not set or wear evenly.
You could do the same with an optical system or even a hall effect dual system using the dizzy but the best and probably easiest method is to dual crank fire it.
I have used twin plug heads for many years on my Ducati 900 and the engine performs very well as far as combustion is concerned but the ingition advance curve needs to be significantly retarded over stock as the revs rise to get the best out of it.
This is due to the 2 flame fronts produced by the 2 plugs shortening the flame front propogation time at the time of ignition and effectively advancing the ignition timing.
Definitely worth the effort.
l8tr
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[Edited on 26/5/04 by tassupervee]
Im not a complete idiot, quite a few parts are missing....
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
BMW motorcycles,on the 2 cylinder boxer motor has two spark plugs per cylinder.At high revs they both fire at the same time and at lower revs they fire apart.It was designed to stop throttle surging at low speeds with the fuel injection.All computer controlled.
BMW motorcycles,on the 2 cylinder boxer motor has two spark plugs per cylinder.At high revs they both fire at the same time and at lower revs they fire apart.It was designed to stop throttle surging at low speeds with the fuel injection.All computer controlled.
BMW motorcycles,on the 2 cylinder boxer motor has two spark plugs per cylinder.At high revs they both fire at the same time and at lower revs they fire apart.It was designed to stop throttle surging at low speeds with the fuel injection.All computer controlled.
There is a back issue of VW Trends magazine which had an article about cutting twin spark plug ports into a Type 4 head. I'll try and find out which issue. It may include some info on how to fire two plugs per cylinder.
Ain't nothin' like the wind in your hair.
BizarreModeratorThe artist formerly known as blue74l
Craig Torrens wrote:Well for all the people that are interested in twin Spark plug setups STAY TUNED !!!! I will tell more over the next couple of weeks !!!
Very practical for street or race.😉
Yeah, baby...
(Oh, and Nissan used them for the Pintara. But that's another story)
So far (seat of pants) the twin ignition looks like a real winner, Just have to collate all the info for a truly scientific evaluation. Should go get some dyno time too.
Stan's really onto something here. Now everyone's gonna want one.
Party on.....
Chris, no dyno, not even fully tuned up yet 😀 but I'm hanging out for a chance to find the time to sort out jetting etc. I have a custom muffler that's dubious at best, so would like to try out a few combos on the day.
basics: idle went straight up from 800 to 1200 rpm, and with no timing adjustment present at this rpm this is a good sign of improved engine efficiency.
torque was definately up in the lower rev range, and now you can nail it at even lower revs without fear of drowning in petrol from a hasty foot.
It drives with two people in the car like it used to with just one. Temperatures are DOWN between 5 - 10 degrees. That's freaky. Plus I can now run less total advance at full throttle (it revs to 7400 rpm, which is scarily fast in second gear)
once I sort out the jetting (dyno and $$$) I'll be getting hold of some slightly stickier rears to stop my roundabout misadventures. Just hope my CV's hold. Losing traction as you punch into third can't be safe... 😠
now we know why there are twin plugged big bore HiPo two valve motors in production to this very day...
:bounce
It's amazing how much better you can get your car to feel when you fiddle with the electrics.
When I changed to a Dick Smith CDI ignition (Thank's to Greg Ward for putting it together) the car became so much smoother. It solved hesitation issues that I thought were caused by the carbs.
I also played with the dizzy advance stops. Not the car goes from 10 degrees at idle to 28. It's much snappier and doesn't detonate as much.
You should start playing with the jets yourself. I'd stick with a 135 main and experiment with airjets from 135 to 180. Make sure the carbs are balanced and adjust the linkage so that both carbs open at the same time and actually make it to full throttle. You could make huge gains in half a day. Perhaps Craig will loan you some jets so you don't have to buy them until you know exactly what you need.
I'm in the mood to give advice. Hope that helps. CYA CT
