Coil on Plug, Pro's vs Cons

[bewstin]

Alright, I've read about 4 posts now that have talked about COP setups. It seems to be a very biased subject in terms of whether or not it is an upgrade.
I'm not going to lie, I love the way this setup looks, and always have. Until i did research on here about it, i always thought it was a much better setup then the stock coil's and wires. Apparently a lot of seasoned DSMers say that its a downgrade from the stock ignition system without a ignition booster. Then there's a ton of people that say how awesome it is and how they've never had problems with it.

All in all I would really love to get a COP setup for my car. My link comes in in 1 week, and once my FIC 1200's, 255, and AFPR get here, I'm going to schedule a day for my tune. I will be shooting for at LEAST 370HP but would really like to make over 400 (dunno if the stock cams will get me there). Should I just stick with the stock ignition setup, or will i be safe with COP???

 

[bastarddsm]

Pro's: none.
Con's: they suck.

The only ignition setup to run is good stock coils, OEM wires, and Copper Plugs. I prefer Autolite #63's for a stockish car, and like AR2594's on my setup.

IF you need a CDI box use a Dynatech.

 

[Calan]

Pros - They look clean and get the coil pack out of the way, and if done correctly can deliver more spark to the plugs.

Cons - They are expensive (biggest new part scam on the market IMO) unless you DIY. Also, they need a good CDI box to work properly, and a CDI box that will last more than a few months will cost a mortgage payment and first-born child.

FWIW - I have a brand new "upgraded" Arc2 box that is on it's way back to Dynatec, after it failed 4 days after installation.

 

[curt-s]

I don't run COP, but the stock ignition system with every part in good condition with proper plugs can handle that power and more. It's all about choosing the right components for the power and making sure everything is in tip-top running order. Lots of engines pushing high horse on stock ignition.
COP is visually pretty though..

 

[jrohner]

Pro: they look higher tech
Con: downgrade from stock.


I still don't see how having COPs is 'cleaner' looking than having plug wires with a cover so you can't even see them besides where they go on the coils.

 

[ForcedFour_com]

With a CDI they will work very well. With a stock ECU it is a downgrade, mostly because the dwell time is not correct. If using an ECU that you can adjust dwell then they can be an upgrade without a CDI if quality coils are used. I have had luck with both an MDS DIS2 and an ARC2 with COP.

 

[bastarddsm]

and if done correctly can deliver more spark to the plugs.

I don't believe that at all. Do you have equipment for measuring the energy that the coil can output?

If you ran sequential spark you could increase the inductance of the primary and increase the spark energy while still allowing time for full saturation of the H field. I'd have to measure inductance of the coils to know, but if they are more than a stock dsm coil, they will have LESS energy than stock at higher rpms.

Also CDI ignitions don't have that much more spark energy than a regular transistor ignition. They do have a much faster voltage rise which prevent low voltage flash over, which is what we call "spark blow-out"

Finally, power output isn't effected by spark energy directly. As long as the flame is lit, it's enough energy.
However in some extreme situations an extremely strong spark can reduce ignition delay, but that doesn't have much effect on power. The extremely strong spark (400+ml) can also improve flame speed, controlling detonation. This is only occurs on extremely high cylinder pressures with alchol type fuels and extremely rich mixtures. Think TAD or fuel car, and Pro MAG 44 or MSD 8.

 

[Ludachris]

Here's why I got rid of mine... if you are at the track and are troubleshooting a spark issue, or just want to check your plug gaps, it can be a pain in the ass to have to mess with a coil on plug setup compared to conventional plug wires. I always had a hell of a time getting those boots back on with a solid contact, and I didn't feel like dealing with it anymore. Not to mention the plate had a way of scratching up the valve cover when installing it.

Looks cool, but I like easier access to the plugs at the track.

 

[Calan]

I don't believe that at all.

Of course you don't. In fact, I was just in a discussion as to which point it would be that you chose to argue with this time.

Sorry, but I don't the have the time or motivation for it today.

Here's why I got rid of mine... if you are at the track and are troubleshooting a spark issue, or just want to check your plug gaps, it's a pain in the ass to have to mess with a coil on plug setup.

Good point. ^

 

[bastarddsm]

Sorry, but I don't the have the time or motivation for it today.

Don't have motivation, or don't have a clue?

 

[Seamus]

Stock coils or if you have a real standdalone, second gen rx7 trailing coils work amazing. I used them back when I ran e6k's and e6s. They are a little known trade secret on some of the fastest mustang racers. They are cheap too.

I know some really fast 4g63 shop cars run COP, but i have to believe its an easy way to get a highly visible part they sell in front of customers eyes.

 

[Ludachris]

Don't have motivation, or don't have a clue?

Necessary? How does this help the OP? And can this be taken as anything but flamebait?

 

[Calan]

Don't have motivation, or don't have a clue?

Oh I could definitely be wrong. But I've never seen a wire of any type that has less resistance than a coil connected directly to a plug.

 

[bastarddsm]

Oh I could definitely be wrong. But I've never seen a wire of any type that has less resistance than a coil connected directly to a plug.

Lol you are. Prepare for a lesson.

#1. Basic relations, V = IR P=IV E = Pt These can be used to derive the losses of spark energy due to the resistance in a plug wire. It ends up being Power lost in the plug wire in Joules = (5*10^-9)/R

This assumes a typical ignition setup having .1J energy, 45000v output, .001s spark duration.

With a 5k ohm wire (typical) that's 10^-13 J in losses.

I can derive it out for you if you wish, but no matter what the "actual" conditions are, the losses in the wire are several orders of magnitude smaller than the energy. Why do you think we use really really high voltage for power transmission?

2. Now onto stock coils vs. COP output.

Energy contained in a magnetic field E = .5LI^2 Where L is the primary inductance, and I is the primary current. Now this energy in the magnetic field is converted to "spark energy" by the secondary, and there are efficiency losses. The only way you can improve that is by going to a better transformer design. Maybe a Torroid, but I don't see any COP's with a toroid core.

Next we look into, the current. We know from above, that the current in the coil at steady state is equal to the Voltage/ DC resistance. From basic E&M studies you can learn that the inductance in a solenoid is proportional to the square of the number of turns and the current in the coil, L = N^2*I. We also know that the DC resistance is proportional to the length of the wire. What all this means, is that if we attempt to increase the energy output by increasing the inductance by increasing the number of turns, we end up increasing the DC resistance which decreases the primary current. You end up counteracting everything, end up with the same energy, and only slightly more inductance.

Finally we can look at the charge time. I'm just going to write this. I = (V/R)*(1-e^(-t/(L/R) Meaning if we increase the inductance, we increase the charge time. Therefore if we have a fixed charge time (like in a dsm with a short dwell) You could actually loose spark energy! Which makes sense because no one can make a COP run worth a fu(k without a CDI. Spark tech is the exception, but I believe they have custom coils made.

I need to take the time and measure a dsm coil for it's inductance, and the dwell time. My guess is it's pretty optimized, and has as short of a dwell time as possible for a the stock coils.

If you want to increase coil output, increase the primary voltage, not the inductance.

At the end of the day it doesn't matter much as I said before, you just need a sharp voltage rise at the spark plug to overcome the tendency for low voltage flashover.

 

[dsmcurse]

^^^i was just about to say that^^^

 

[Black-Out]

Love the break down sir.......
William-

 

[delta448]

Therefore if we have a fixed charge time (like in a dsm with a short dwell) You could actually loose spark energy!

If you use ECUFlash, coil dwell time is editable. I'd be surprised if Link doesn't offer that as well. Not ideal, especially with still being waste-spark, but if the coils can take it, there's more spark energy to be had with a simple re-flash. I agree that a higher V would do the same thing, again granted the COP coils of your choice can withstand it.

As far as OEM parts go, stock DSM ignition coils are kickass. 90% of us will never need anything other than the stock coils and there's so many other ways that the money would be better spent.

Don't fix what isn't broke.

 

[mysticj]

Pro's: none.
Con's: they suck.

The only ignition setup to run is good stock coils, OEM wires, and Copper Plugs. I prefer Autolite #63's for a stockish car, and like AR2594's on my setup.

IF you need a CDI box use a Dynatech.

I never ran aftermarket COP, I just use Hyundai ignition setup. Why? Tired of the external transistor and I have a Cyclone IM.

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[bewstin]

Well i'm sold on the stock ignition setup. I won't be getting COP after reading all the downsides. Honestly i wanted it for the look. I'm 100% about function over appearance, so I've definatly been turned off to the COP setup. Thanks for all the info and helping me make up my mind haha.

 

[bastarddsm]

I never ran aftermarket COP, I just use Hyundai ignition setup. Why? Tired of the external transistor and I have a Cyclone IM.

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Thats basically a stock system......Just more compact.

Well i'm sold on the stock ignition setup. I won't be getting COP after reading all the downsides. Honestly i wanted it for the look. I'm 100% about function over appearance, so I've defiantly been turned off to the COP setup. Thanks for all the info and helping me make up my mind haha.

I like the stockish look. I relocated my coils to where the PS reservoir used to be and run the wires over the cam gear cover.

 

[WES_393]

Here's the reason I hate COP:

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I bought a COP setup/plate from a freelancer. Very nice piece and plugged right into the stock coil pack plug. Worked very well with one exception: Coils exploding. While hooking up my gauges, I left the ignition forward to find the hot fuses. Within 5 minutes I heard a loud pop, looked up to see tons of smoke. Come to find out coil #1 popped completely blowing out the side and covering my bay in tar-like crap. First thought was a missing ground wire or messed up wiring in the plate setup. So I spent hours tracing and inspecting wires, zero problems found. I replaced the burnt coil with a new one from Oreilly. I turned the key forward watching the coil plate and sure enough, within 60 seconds coil #3 exploded again and filled the shop with fumes.

Took the new coil back and used the money for a used coil pack and NGK wires. Never had a problem since. My guess is that the ignition system was charging the coils to fire, but the coils couldn't handle not discharging for a few minutes and got too hot. Whatever the reason, I will never waste money on COP ever again. Although I have contemplated using the newer 4g ignition system which is much like the Hyundai COP/Wire hybrid shown above. Just not sure if any gains would result from using 2 less plug wires.

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[bastarddsm]

^ nope. Stay stock stay happy. Stock coils, NGK wires.

 

[WES_393]

I figured. Stock is cheap, simple, and reliable anyways. So I guess the general consensus is keep the stock setup as long as possible.

 

[Calan]

Lol you are. Prepare for a lesson.

Cute. But FWIW, I learned Ohm's law and "Eli the iceman", and was working on satellite transmission systems for the military before you were born. At this point, I'm both too old and just plain not interested in any refresher lessons on that subject.

Anyway, as for this:

The only ignition setup to run is good stock coils, OEM wires, and Copper Plugs.

if done correctly {a COP setup} can deliver more spark to the plugs.

I don't believe that at all.

Just to be clear on this (coil theory aside, which was very well written BTW), you are saying that under no circumstances (I.E. "done properly"), can a COP setup deliver more spark energy to the plugs than a stock ignition. Right?

 

[c2ypt1c]

Lol you are. Prepare for a lesson.

#1. Basic relations, V = IR P=IV E = Pt These can be used to derive the losses of spark energy due to the resistance in a plug wire. It ends up being Power lost in the plug wire in Joules = (5*10^-9)/R

Cute. But FWIW, I learned Ohm's law and "Eli the iceman", and was working on satellite transmission systems for the military before you were born.

I love it when people regurgitate ohms law from wikipedia and think they are Charles-Augustin de Coulomb...a lesson in ohms law? Really? V = IR, wow...my physics professor said it best - "this course can be summed up into five equations"