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Shuie 02-18-2005 06:58 PM

Cheap & Easy twin ignition?

Any thoughts? Seems like a solid idea.

Seems like a simple way to twin plug. Cant be too expensive either. Not as elegant as a RSR distributor, but as long as it worked well and was affordable Im not sure I would care.

Does anyone know if one of the racing outfits sell a twin ignition setup like this?

emcon5 02-18-2005 07:15 PM

That setup came up in this thread:


kenikh 02-19-2005 02:52 PM

I just ran across this crank fire set up for the 911 (no, I'm not the seller): 673&rd=1&ssPageName=WDVW

Seems to me that you could set up the low voltage sender to be wired to two MSD ignitions and coils and drive dual plugs that way. Since it is just a sending unit, it should be a snap. Am I completely over simplifying this?

This setup would be far cheaper than a 964 or RSR setup if you bought all of the MSD components used. They are a dime a dozen from the Detroit crowd on Ebay...

afterburn 549 02-19-2005 04:10 PM

I know there has to be a cheaper way to do this with all the aftermarket stuff out there...If one of the electrical gurues would just speak up!! as the trigers and wheels are cheap ,,just takes something to adj. the timeing.......and that is completely out of my game.
I can see it- 3 coils (wasted spark) or 6 coils,crank triger and a whatsabutsit to keep it all timed. Now I know someone will jump in and say buy a ready made ign.but they are spendy

Wayne 962 02-19-2005 05:18 PM

That's very clever - I can't say I've seen anything like that before. Still, doesn't look super-cheap to me. That's a special distributor on there, and a bunch of custom brackets and pullies.

Crankfire is $1500 - that's really the benchmark that you need to beat, as it is the cheapest, and best-performance solution.


Shuie 02-19-2005 05:23 PM

The only thing I struggle with on the crankfire setup is that I have yet to see a post or tech article that details everything that is needed and how it is to be installed. I know that I need coil packs and the trigger pulley wheel, but thats it :confused:

Wayne, I know you guys sell all of this stuff. Is there a list of Pelican part numbers or a packaged setup that covers everything?

afterburn 549 02-19-2005 06:35 PM

Electromotive sells the stuff thrue P.P.....not cheap,HPX system,,and I do not think it will integrete if you step up to inj. later ,??will it Wayne??
S.D.S. is nice cause you do not have to own a dyno....back to my pt,, there must be a "box" sold seperatly that will advance and retard as needed if the other parts are on board....(logic board)??

Shuie 02-19-2005 08:12 PM

I wont be stepping up to engine management or EFI.

Is $1500 the bottom line for ignition only? Sounds good. What all do I need to buy? HPV-1, HPX, trigger?

KobaltBlau 02-19-2005 10:45 PM

you could do megaspark (sand alone, no efi) for less, if you have the required interest/ingenuity:

here's a listing of all the megasquirt related ignition stuff:

kenikh 02-19-2005 10:58 PM

MSD sells a number of ignitions with fully programmable ignition curves as well as programmable boost retard features for the truly adventurous. That $200 crankfire distributor kit is fully compatible with MSD ignitions. It just CAN'T be as hard or as expensive as it seems; it only seems logical that a Porsche can benefit from the commoditization of the automotive electronics market that the muscle car heads enjoy.

BTW, Kobalt, the Megaspark links are right up my alley. Thanks!

afterburn 549 02-20-2005 12:41 PM

Thats what I mean,,if I knew What went with what it could be done..having said that I have called all these ign. peo in the past and everyone of them dose not understand what they are selling.The guy ans. the phone would be just as happy saying "would you like fries with that".Maybe we can stir the pot here and get some teck to que up...

Oldporsche 02-20-2005 05:36 PM

I started a similar thread over on the big 911 board.

My thoughts were these:
1. The second distributor doesn't have to be a Bosch one. It only has to have the same distributor curve. One could use the toothed belt drive of a MFI fuel pump. It's a one to one rotation with the chamshaft.
2. You could use a pertronix unit in the original distributor and split the output. If you didn't want to use the distributor advance, you could use an msd ignition curve unit. and split its output to a couple of coils or msd units. (You can find them on note boards at your local hod rod shops)

I think that this could be done way cheaper than $1500. In fact you would not even have to use the MFI drive, just mount two small cog drive belt pullys, one on the end of the cam (using the mfi seal set up), the other on the end of the distributor and use the compatable drive belt.

As a matter of fact, I think CIS equipped cars use a mount in this position to hold a belcrank for the throttle linkage.

Any thoughts?

David Duffield

Chuck Moreland 02-20-2005 05:57 PM

Clever for sure. I'd be concerned about the advance curve. Each distributor is working independently, yet the curves need to be close to identical. I'd like to see them tracking within 1 degree, hard to imagine independent mechanical advance mechanisms mapping that close. But maybe they do.

Oldporsche 02-20-2005 06:05 PM

You know in a 964 distributor, doesn't one distributor top lag the other in spark delivery per degree of crank rotation?

Using a distributor machine, I would guess that an experienced hot rod type could pattern a couple of curves very closely.

BTW, MSD offers a cog belt drive billet distributor. Unfortunately its for a V8.

David Duffield

kenikh 02-20-2005 07:01 PM


Originally posted by old_porsche

2. You could use a pertronix unit in the original distributor and split the output. If you didn't want to use the distributor advance, you could use an msd ignition curve unit. and split its output to a couple of coils or msd units. (You can find them on note boards at your local hod rod shops)

David Duffield

This is a great idea! This seems to be the easiest and cheapest option I have read. Has anyone tried this yet? It seems like the best way to get dual plugs, yet keep it stealth by using the stock distributor.

911pcars 02-20-2005 10:49 PM

I wouldn't trust two separate mechanical advance mechanisms to mirror exact advance curves. And if they're not complementary, then you'd be leaving some HP and torque on the table. Modifying the curves to maximize power would be a beyotch as well. I'd think it'd be more accurate (as well as adjustable) to do it electronically using a single MSD-type box. The two distributors would do only that - distribute the high voltage spark determined by the ignition box.


afterburn 549 02-21-2005 05:38 AM

Ok what box do we need to get this result??

BURN-BROS 02-21-2005 06:22 AM

This mod is indeed clever! It looks like they gutted the dizzy(has a cover plate where wires/vac advance should be coming out?) My hunch is it is along for the ride and only the main distributor is running things. The advance curve isn't as important if they did it this way.

Some of the old 4 cylinder porsches used two dizzys on the cams for twin plug. The 959 has a very low profile caps and the dizzy pointed in the other direction. it is a viable option if you have a lathe(or a friend who has one)

Oldporsche 02-21-2005 06:39 AM

In this thread:

Grady Clay describes using the drive off the left cam bank to rotate a spindle holding a disributor rotor inside a screw down distributor cap. The rotor simply distributed the spark. From what he said, I deduce that the contact of the rotor was very long to make up for the lack of timing advance in the secondary distributor? I would like to explore that.

In the same thread Henry Schmidt showed a 962 distributor that did the same thing.

From what I see so far this is a doable project.

Good luck
David Duffield

Mike Bonkalski 02-21-2005 10:51 AM

As Andy mentions earlier, Megasquirt can be used to control just spark.

Megasquirt in conjunction with a <gasp!> Ford EDIS ignition module, coil pack, VR sensor and 36-1 notched wheel mounted to the crank pulley will give you distributorless ignition at a great price. EDIS has been tested accurate to 9000 rpm. Another benefit is the ability to piggy back another coil pack onto the ignition module to allow for twin plugging.

If you build the Megasquirt yourself and salvage the EDIS parts, you can realistically spend no more than $400 for twin plug, distributorless ignition.

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