Thread: Inductive coil tech, coil-on-plug (COP) tech and more.

This is basically what you need to do. And no, I don't think you need any ignitors at all with the CDI + COP system.



Start on the left on this picture. Your AEM EMS will have 4 ignition signal outputs which will go to the CDI box. The CDI box will have 4 power outputs for the coils and some grounds (in this case, two but you might have 1 or 4). That's basically all there is too it, except you also have power, ground and relay signal for the CDI box's power and on/off needs and the CDI box provides a tach output signal. That's really the gist of it I believe, but whichever CDI box you get will have the correct directions.

on the picture it shows coils 1 and 3 together and 2 and 4 together. Im assuming this is just for grounding purposes and the CDI sends the voltage input to the coil insead of the way a coil normally operates where it has a constant 12v power feed then is grounded by the ecu signal. Im guessing they stagger it like that so there is not two sparks happening at the same time as a waste spark system would do.

And as far as the tach goes, your tach signal is normally fed coming off your ecu harness, would i still use that same ecu tach signal or use the CDI box tach signal and solder it into the tach signal wire that would normally go to the ecu and tachometer since its no longer getting a tach signal from your ignitor.

I guess the aem can also get a tach signal from the crank position sensor as well, ill probably just have to do it as i go. I can pick up on stuff pretty quick.

Again just getting an idea. And thanks for the pic Ben, your awesome.

What do you think of the AEM twin fire CDI box. Seems like its got some punch behind it after reading the specs.

Good specs and good price on AEM CDI box. Don't know anybody using one tho. That is on the top of my list for options, unless there is something I've missed.

I think the tach signal can be done a few different ways. I'm not sure if you'll need to make any use of the CDI tach signal. You'll have to find out when you get the directions. I've never wired one of these up before. The factory system is not as logical as I thought it was either.

All I know is that Dan Martin doesn't think the AEM CDI stuff is worth buying. It has lots of problems and is apparently crap, and discontinued? I can't find the thread though... It's somewhere.

AEM is the cheap solution. Not sure it's the right one though.

I remember something about their cdi coils being crappy but im not sure on the boxes though. And like you said AEM is pretty good about supporting their products. I know there wont be any issues wiring it up and setting it up right. Im not sure if i want to even use the multi-spark feature as i dont think i really require 20 sparks every ignition cycle. I guess if that is adjustable to maybe a couple sparks per cycle then yeah. But with that and boost having a multi spark could cause some problems and im guessing thats why they have the warning on there if incorrectly setup with your vehicle that it can cause damage.

Any other ideas on some boxes that dont cost an arm and a leg. haha I figure im trying to keep the box around the $300-350 range.

No idea on cheap CDI. All I know is that Mallory is trusted, and expen$ive.

Multi-spark is for stabilizing idle and low load/rpm operation. The spark from a CDI driven coil lasts maybe 100x shorter than one from a battery driven coil so lots of times the spark happens too fast to ignite anything at idle or low load or low rpm so having multiple sparks makes sure the mixture ignites. It's a good idea, but as load rises even a little you want fewer and fewer sparks until you only need one.

Yeah im sure its rpm based as well.

I might give the AEM a try with some motorcycle COP's.

Another question is with the extra spark energy should i continue to use the standard bkr7e's or use an iridium 8 heat range plug.

I ran my 7 heat range copper plugs with no issues on my last setup. after 7k miles i pulled them out and they looked great, little sooty from richer mixtures but overall in great shape, no sign of deterioration and detonation. But with an extra 200whp and hotter spark i might want to use something other than the coppers.

Although if you start to have issues, sometimes having copper plugs can be a good thing. Rather the plug melt than the piston. haha

I don't think the extra voltage means anything when it comes to spark plug heat range. The amps will be lower, so the heat produced should be about the same...
Obviously with 200 more HP you might want to go up to 8's. Frankly I'd think 7's are too hot for your current setup but from what you're saying they seem fine.

The issue with too hot of a plug is not worrying about melting the tip (which might happen) it's worrying about pre-ignition.

yeah true, I think the 8's only come in iridium so i might just go with those plugs.

Thanks for all the info Ben, its very helpful.

Cant wait to get this all together and see how well it works out.