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> Twin Spark, who's done it? how?
brer
post Jan 20 2007, 11:53 AM
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QUOTE(Jake Raby @ Jan 19 2007, 09:30 AM) *

QUOTE(ChrisNPDrider @ Jan 18 2007, 09:03 PM) *

Do you think a twin plug 1.7 with a heavy rotating mass, like 9.5:1 CR, and high power ignition could get 40-50 mpg on 91 octane in a stockish 914? (IMG:style_emoticons/default/beerchug.gif)


My "Super 2 Liter" combo is based similar to this with high velocity 1.7 heads...

It has gotten 51 MPG with a SINGLE plug.

It would be very hard to do a twin plug on a 1.7 casting due to chamber shape and volume.

We base the twin plug heads on the 1.8 castings.



is this the long stroke small piston engine?


regarding time delay on the inductive pickups.... they are used to set the timing of the engine triggering the timing light so the delay must be minute. milliseconds.
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alpha434
post Jan 20 2007, 02:16 PM
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QUOTE(DNHunt @ Jan 20 2007, 11:21 AM) *

You could use EDIS to trigger COP but, it's not as easy as it seems on the surface.

At first is would seem that a module for a 8 cylinder car on a 4 cylinder engine might give 4 cylinder twin plug but, it won't work because the sparks are miss timed. It will fire 8 times in 720 crankshaft degrees (1 engine cycle). This means it fires near TDC (good) but also near BDC (bad).




A custom rotor with two outputs.
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brer
post Jan 20 2007, 02:50 PM
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hasn't the idea of linking two edis 4 modules to the same read sensor been thrown out already? or is the problem one of sync between the two.


The machinist I know has a program written to notch the type 4 fan so it could be used as the edis crank fire wheel.
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Aaron Cox
post Jan 20 2007, 06:50 PM
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machining the fan to be an EDIS wheel is a killer idea!
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Crazyhippy
post Jan 20 2007, 06:56 PM
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Should look into doing DOHC instead of dual sparks... Much more HP potential...

Adding watercooling will help keep temperatures morre consistant too, And If you're doing custom heads, do a Hemi style, w/ the spark plug centered, so you dont need a 2nd plug.

Then get the heads to seal better, and throw some boost at it (IMG:style_emoticons/default/biggrin.gif)

BJH
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brer
post Jan 20 2007, 09:00 PM
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QUOTE(Crazyhippy @ Jan 20 2007, 04:56 PM) *

Should look into doing DOHC instead of dual sparks... Much more HP potential...

Adding watercooling will help keep temperatures morre consistant too, And If you're doing custom heads, do a Hemi style, w/ the spark plug centered, so you dont need a 2nd plug.

Then get the heads to seal better, and throw some boost at it (IMG:style_emoticons/default/biggrin.gif)

BJH


or you could skip 20 years of technology and obtain some 2007 Mercedes Benz valve control servos and do a 100% digital valve train. (IMG:style_emoticons/default/w00t.gif)
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Crazyhippy
post Jan 20 2007, 09:17 PM
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I prefer Rotary Valves....

Linky Linky

All it takes is $$$

BJH
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brer
post Jan 20 2007, 09:19 PM
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you win that round.
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Mueller
post Jan 24 2007, 08:36 PM
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brer, I think I found a solution for firing the twin-plugs via a distributor...

Compufire has a kit that has some electronic that go into your distributor which in turn fire a twin coil pack (wasted spark)

I would almost be willing to bet that if you connected up another coil pack, the control modual that resides inside the distributor would also be able to fire the second set up plugs.

so for less than $300 (according to ebay) you would have all that is needed to fire all 8 plugs....

I'd also bet that you could fit the parts needed into a Mallory body so that you could easily set your advance curve if you wish.

Attached Image

compufire dis-x
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McMark
post Jan 24 2007, 09:09 PM
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Or wire up two sensors 180 degrees off and it's not wasted spark anymore (1 coil per cylinder w/ two spark plugs). That looks pretty cool Mike.
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ClayPerrine
post Jan 24 2007, 09:19 PM
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QUOTE(McMark @ Jan 24 2007, 09:09 PM) *

Or wire up two sensors 180 degrees off and it's not wasted spark anymore (1 coil per cylinder w/ two spark plugs). That looks pretty cool Mike.



It won't work that way. You get a dead miss. The "waste spark" ignition is based on the fact that it takes really high voltage to jump the plug gap under compression, and a lot lower voltage to jump the plug gap when the exhaust port is open. If you have both under compression, it doesn't have the voltage to fire the plugs.
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Mueller
post Jan 24 2007, 09:39 PM
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QUOTE(ClayPerrine @ Jan 24 2007, 07:19 PM) *

QUOTE(McMark @ Jan 24 2007, 09:09 PM) *

Or wire up two sensors 180 degrees off and it's not wasted spark anymore (1 coil per cylinder w/ two spark plugs). That looks pretty cool Mike.



It won't work that way. You get a dead miss. The "waste spark" ignition is based on the fact that it takes really high voltage to jump the plug gap under compression, and a lot lower voltage to jump the plug gap when the exhaust port is open. If you have both under compression, it doesn't have the voltage to fire the plugs.


as I think Jonny Carson would say..."I didn't know that" (IMG:style_emoticons/default/smile.gif)

makes sense once you think about it...they do recommend a huge .050" gap...you could make the gap smaller to make the "jump" easier, but what fun would that be (IMG:style_emoticons/default/smile.gif)
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East coaster
post Jan 24 2007, 09:41 PM
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From the aircraft world: http://www.greatplainsas.com/2007.pdf

Type-4 dual plug heads for $680 a pair.
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racerbvd
post Jan 24 2007, 10:12 PM
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Twin plug Type IVs aren't new, I have a 2.1 that Jay at RPM in Port Orange, FL. (long since closed, Jay MIA) back in the mid 80s, some of his work including the twin plug set up (using the Nap Z dizzy) was featured in VW & Porsche magazine a few times. I plan on using that engine in my 76, but updating with a Jakobs ign. system. My 911 was done by iSystems Performance.


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jd74914
post Jan 24 2007, 10:34 PM
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Lets see some pics of that TIV Byron (IMG:style_emoticons/default/biggrin.gif)
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Brando
post Jan 25 2007, 10:37 AM
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Oooooooh... $682 a pair?

That almost makes it affordable. But I wonder what a good shop would charge just to do it on a good set of heads?
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mudfoot76
post Jan 25 2007, 12:46 PM
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QUOTE(Brando @ Jan 25 2007, 11:37 AM) *

That almost makes it affordable. But I wonder what a good shop would charge just to do it on a good set of heads?


This guy might know a thing or two about cylinder heads (IMG:style_emoticons/default/smile.gif)
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brer
post Jan 25 2007, 01:20 PM
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QUOTE(mudfoot76 @ Jan 25 2007, 10:46 AM) *

QUOTE(Brando @ Jan 25 2007, 11:37 AM) *

That almost makes it affordable. But I wonder what a good shop would charge just to do it on a good set of heads?


This guy might know a thing or two about cylinder heads (IMG:style_emoticons/default/smile.gif)



never heard of him.

(IMG:style_emoticons/default/smile.gif)
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Brando
post Jan 25 2007, 03:09 PM
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QUOTE(mudfoot76 @ Jan 25 2007, 10:46 AM) *

QUOTE(Brando @ Jan 25 2007, 11:37 AM) *

That almost makes it affordable. But I wonder what a good shop would charge just to do it on a good set of heads?


This guy might know a thing or two about cylinder heads (IMG:style_emoticons/default/smile.gif)

Poop, I'ma have to call him again for a price, because it isn't listed under his list of services.
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Aaron Cox
post Jan 25 2007, 04:11 PM
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QUOTE(Mueller @ Jan 24 2007, 06:36 PM) *

brer, I think I found a solution for firing the twin-plugs via a distributor...

Compufire has a kit that has some electronic that go into your distributor which in turn fire a twin coil pack (wasted spark)

I would almost be willing to bet that if you connected up another coil pack, the control modual that resides inside the distributor would also be able to fire the second set up plugs.

so for less than $300 (according to ebay) you would have all that is needed to fire all 8 plugs....

I'd also bet that you could fit the parts needed into a Mallory body so that you could easily set your advance curve if you wish.

Attached Image

compufire dis-x


that gives you a crappy 009 advance curve
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