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juicersr's Avatar
 
Join Date: Apr 2005
Location: Wilmington,NC
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More power from a distributor than Coil packs/DFU's?

Well, it looks like i am headed for a new stand alone engine management system. The TEC1 is basically 'untunable' without the original fuel maps according to guys at both Clewett and Electromotive. Even if we had the original map, the TEC1 would limit any serious tuning. From all of my research, it's a relic from the early days of aftermarket EFI that needed to go sooner or later. Anyhoo, i have been researching and comparing the various systems out there, from Link to Spectre, MS, etc, and i have heard something interesting from two different reps - that more power may be obtained from replacing the coil packs with a stock distributor vs DFU's. The only advantage with DFU's was in twin plug engines, mainly with cost. I thought that the one of the advantages of these systems was TOTAL management of spark, timing, etc. I thought that mechanical distributors, while excellent, were nowhere near as efficient as coil packs/DFU's in managing spark. Am i missing something here?
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Old 06-28-2008, 07:52 AM
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I think the differences (advantages and/or disadvantages, depending on your stand in the argument) is not so much DFUs Vs. a traditional dizzy, it's inductive ignition Vs. CDI (Capacitive Discharge). You can obtain CDI either a traditional dizzy triggering CDI boxes, or something more modern - coilpacks with crank or cam sensor managed with an ECU of some sort. M&W is an excellent example of a "modern" CDI system.

I just removed the inductive Electromotive XDi twin plug ignition from my car and went with the JB Racing 12 point dizzy and MSD CDI boxes. I do think my engine picked up a bit more torque on the low end, and it starts even easier than before, but I did like the ability to dial in an ignition curve and retard the timing via MAP sensor...fuctionality my XDi provided. It's all about the compromises...I'm happy I made the change.

Also keep in mind I'm CIS, in your case it might be even easier to make the change to a more modern CDI system, in conjunction with whatever fuel management you decide on...
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Last edited by sand_man; 06-28-2008 at 09:52 AM..
Old 06-28-2008, 09:46 AM
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CDI will deliver more intensive spark lasting shorter time. It might or might not result in more power and it will certainly help sustain spark at high boost when less powerful systems will have problem.

That being said my personal opinion is that as long as spark is sustained by ignition, it's OK to run whatever system you use. Also, I find fine-grain advance control much more usable than marginally more ignition energy.

Also, a single coil that is charged/discharged 6 times as often as distributorless system is much more sensitive to dwell timing. Add the cost and wear of distributor system.

So to round it up:

I would chose programmable distributorless non-DCI ignition instead of CDI/dizzy combo any day of the week as long as coilpacks can deliver enough juice to keep plugs firing during boost. Twin plugging would tip the balance towards coilpack even further when costs are compared.
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Old 06-28-2008, 10:18 AM
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Jeff, thanks. Those JBR dizzys sure are sweet! I really need to see your engine set-up u closed and personal some day. As soon as i get this thing tweaked, gonna make a Raleigh run. Shouldn't you be down in Charlotte at the Parade instead of online, or are u working this weekend like me?

Goran, thank as well. My tuning guy corroborated essentially what you said.
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'79 930/934 replica
80 RSR-look(Now in Sicily)
914/6 2.7 (Projekt 908/3)
1965 Karman Ghia-Class winner 2007 Carrera Panamericana/Ducati 900ss/GhezziBrian STW
D-Zug Produkte/D-Zug.com
Old 06-28-2008, 11:29 AM
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