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Coil on plug or conventional coil for Duratec
ceebmoj - 12/4/15 at 08:45 PM

I'm in the process of building the engine loom for my Duratec engine. It looks like the total cost of going coil on plug is about the same as a conventional coil once you have factored in a set of HT leads. Which approach do people recommend?

FuryRebuild - 13/4/15 at 08:35 AM

Coil on plug.

You get a better spark because each individual coil gets longer to charge, rather than wasted spark, where you have one coil firing twice per four strokes, which means the other time it fires is on the exhaust cycle of a opposing ignition cycle, hence the moniker 'wasted'. Sp, IIRC, the coil pack on your (and my) duratec is wasted spark.

Then there's the final system, which is conventional coil, which fires every ignition cycle and is a lot bigger.

On my pinto (so it's not relevant here), I used MSD capacitative discharge, controlling my coil. It was excellent and from the moment i fitted it, my awkward to start pinto became a dream to start. It would usually light up first turn of the crank from cold, no choke.

peter030371 - 13/4/15 at 09:12 AM

This is a quote from SBD who fit COP and why they do it (its talking about the loom kit they sell);

It has been made to fit the coil on plug version since the coils are cheaper than buying the older coil pack & HT leads. They are also neater with fewer components to go wrong & when used in cars such as Escorts, there are no problems trying to locate the coil pack.

I already have a perfectly good coil pack and HT leads so my build will stick with that but if you are replacing these then it looks like the economics alone is a good enough reason to go COP to me

FuryRebuild - 13/4/15 at 09:29 AM

I've been trying to find the reference in Haynes fuel injection book, but can't at the moment. I also have a ignition book as well that i'm trying to find.

For me, packaging is also important. I'm lucky that in my fury, the coil pack and thermostat housing fit as per, but I don't want to use the coil pack.

Better sparks mean a better burn.

BaileyPerformance - 13/4/15 at 11:04 AM

COP produces no better spark than a coilpack.

We tend to favor Ford coilpacks as we have found these to be better over most COPs assuming you have decent leads.

In my opinion COPs can suffer from overheating due to there location, (reducing there output)... a happy coil is a cool coil!!

ceebmoj - 13/4/15 at 04:40 PM

Thanks for the input.

@baily performance how have you found the conventunal coil to be better?

BaileyPerformance - 14/4/15 at 03:29 PM

quote:
Originally posted by ceebmoj
Thanks for the input.

@baily performance how have you found the conventunal coil to be better?


Very high RPM engines or high boosted engines need a high power spark with long duration, we swapped from COP to Ford coilpack on a Hayabusa engine (running megasquirt) and picked up a small amount of power and a chunk of torque. (1.1mm plug gaps)
This was probably due to the factory coils been "just good enough", the ford coilpack to a tough thing that will stand high dwell, the COPs are not and will not tolerate over dwell (overheat)

dave_424 - 14/4/15 at 04:23 PM

I use a ford coilpack on my turbo ZX9 engine, I used some dwell settings found online for megasquirt and it works a treat so I agree that they can withstand high/incorrect dwell settings just fine.

I run 15psi of boost and 13k rpm rev limit and have had no spark problems

Oddified - 14/4/15 at 05:17 PM

What sort of increased dwell times are you talking about here in these extreme circumstances? just interested that's all

Ian

BaileyPerformance - 14/4/15 at 06:29 PM

quote:
Originally posted by Oddified
What sort of increased dwell times are you talking about here in these extreme circumstances? just interested that's all

Ian


Using Megasquirt,
Normally 3.5-4.0mS dwell is fine for a Ford coilpack, and produces a decent spark, we have run them a 8mS without an issue. The current to the coipack is over 15A-20A at these settings, so the wiring needs to be large enough to avoid voltage drop.

Megasquirt uses some very manly ignition drivers which will take some punishment.

A typical COP is 2.5mS.

On big boost turbo cars the extra dwell avoids spark blowout, even with over 1mm plug gaps.

Chris_Xtreme - 15/4/15 at 07:25 AM

you could always go for CNP and choose the LS2 truck coil.. They read like they are very good and I went for 8 of them.. (to be honest mainly to do something different to a couple of ford units as I don't have a mega high performance car)

http://www.megamanual.com/seq/coils.htm

you will need different HT leads as the coils have different sockets, I got mine made up in the US.