<div class="bbWrapper">I'm on my third set of stock coils, my first set fried because I had the spark edge i nthe haltech set to falling (the "on signal was interpreted as an off signal, and the coils melted after about 30 seconds.) The second set of Mazda coils ran at 10ms after about a week. Since they're a constant charge type coil, 10ms at 6-7000 RPM on a waste spark setup didn't leave much room for "off" time for the coils. (Basically constantly on with that much dwell) and after a week or so they overheated and melted. My third set are some NAPA ones (Airtex IIRC?) and they're still running strong for a year and a half now at 8ms. <br />
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I knwo what you're saying about the equal length setup, but I don't buy it. Think how much energy and how quickly it's sent through those wires. The "delay" or "different resistance" just isn't great enough to do anything. Look in the FSM for the resistance inspection on the coils.<br />
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Coils have no impact on how much boost you can run, to a point. I've never had spark blow out on me at 24psi with 8ms dwell time and a .028" gap (tight I know) so I'll leave it at that.<br />
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8 ms of dwell on stock coils?<br />
how long did they last?<br />
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i run bosch HEC715's, which are some of the biggest bosch coils going - running individual coils (as opposed to wasted spark) and they die quickly at 4.5ms of dwell.... 4 is considered safe and they can support far higher dwell than the stock ones ever could.<br />
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The 1.8 coils may still be wasted spark, but being off the engine, and not covered by the engine cover, they are likely to dissipate heat far better. In addition, because you can have equal length leads with the 1.8L coil packs (equal length is better than uneven, even if the equal length is longer - equal length means equal resistance which in turn helps with equal spark - the same amount of power is applied to each plug, instead of one being stronger than others etc). measure the reistance on the stock leads - and you'll see that they are terribly missmatched.<br />
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As for how much boost your coils can handle, it doessn't overly matter. Sure, more boost (well, higher cylinder pressure) will require a bigger/better spark, but the AMOUNT of boost should have no bearing on how well the coils operate - its simply a case that less dwell, and less available power in the ignition system will ultimately limit how much boost you can push.<br />
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I'd be very keen to know what state the stock coils were in after prolonged operation at 8ms dwell.
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