I contacted a company called NPBoosted.com about a set of performance coils they offer. They sent me a technical data sheet but to be honest I'm not sure I know what it all means. I know that our stock DENSO's are 40K volts on the output side, as are these. Beyond that I have little idea what the rest mean other than they are higher (I do understand that more primary voltage is good and creates a hotter spark).

I would appreciate any feedback on whether this would improve spark quality on my supercharged engine (91 + 100 octane). Specs sheet is attached and I copied it below in case it cannot be opened.

TOYOTA UF156 ignition coil test report
Model: 90919-02212 / UF156 Date: 2020-04-20
Test condition: indoor temperature: 23±5 °C relative humidity: 60 %
Initial parameter: rated operational voltage 14±0.1 V,
charging time (Dwell) 4.0 ms,
discharge frequency= 50 Hz
Zener voltage 800 V

Original Toyota UF156
Primary current: 4.8A
Discharge time 2.50ms
Discharge current 48mA
Ignition energy 48mJ

Our Coil
Primary current: 6.2A
Discharge time 2.70ms
Discharge current 50mA
Ignition energy 54mJ

Attached Images

Toyota UF156 coil test report may 27 2020.pdf (36.7 KB, 275 views)

First, the test conditions: They are supplying 14V to the coils (reasonable guess for standard engine conditions), pulling current through the primary side for 4.0ms every 20ms (50Hz, or equivalent of 3000rpm on our wasted spark engine). Also note they are running the tests at room temp, not engine temps! Who knows how each will degrade with temp (resistances increase with temperature, lowering output power)

Primary current: How much current the igniter drives in/through the "low voltage" side of the coil. This is what the igniter supplies to the coil with each ignition event. The upgraded coil draws more current, meaning it is lower resistance on the primary side. In this case, about 30% more current draw. This puts more stress on the igniter and hopefully isn't a problem.

Secondary peak voltage: A representation of how 'far' the spark can jump. Higher voltage = longer arc.

Secondary discharge time: amount of time it takes for the coil output voltage to drop from the peak voltage to some percentage of the peak (maybe 10% - it is unspecified).

Discharge current: similar deal, more output current across the same load = more power.

Energy: Basically power x time = energy. The percent increase in discharge time x the percent increase in discharge current (into the same load) = the percent increase in output energy.

In the end, you are getting 12.5% 'hotter' spark. It has the theoretical ability to ignite 12.5% 'more' air/fuel mixture. Whether this matters or not depends on whether your current ignition system is keeping up with the needs (extra spark doesn't help once you get over 'sufficient').

Notice the diminishing returns here: 30% more input power only gets you 12.5% more output power...

-Charlie

Thank you very much, I appreciate the layman's terms explanation. Google search was doing me no good with very technical articles that I was not able to understand.

I did also notice the amps were roughly 30% higher but output was much less than that. I might give these a try, need to look and see if they have any sort of return policy first.

What if you bought 3 MSD6’s to drive your factory coils? Those put higher voltage to the primary side to get the faster hotter spark. They have their own voltage source and use your coils signal to control the MSD6. Plus it’s multiple spark.

MSD makes a DIS setup that gets a better spark also and won’t overload your ignitor box.


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I've looked at their products and they do work well. These coils were just under $100 shipped so it's a cheaper experiment. If they do show a performance increase, then I might consider upping the spark energy again down the road.

I thought about the three MSD6’s when I was rebuilding the engine. Where to put 3 of them will be hard. And I’ve looked for a used DIS 4 and they just don’t show up.


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I'm curious to see if these increase the performance at all. What I really want to see is an upgraded set of plug wires that aren't the size of a pencil. It's odd the plug wires in these are so long and so small compared to basically any other motor I've seen where the plug wires are shorter and twice the diameter. I'm unfortunately probably adding meth injection to mine despite really not wanting to so having a stronger spark to keep from quenching out cylinders would be nice

Well you are in luck, a set of Magnecor KV85's showed up at my door yesterday. I plan on doing a few logs as is, putting on the wires and do a few more logs, then put the coils in and do a few more logs. Stay tuned, I hope to do it in the next week or so.

Please ohm out the wires. I’m curious what resistance they are.


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I've been told they are high resistance, much higher than regular carbon core wires. We'll see!

Yea, I read their site a while ago about low resistance doesn’t matter as much as EMI suppression and high heat resistance does. It was probably worded that way because their wires had higher resistance than a competitor.

I’m betting they are still pretty low. Maybe not 1k ohm per foot like my CarQuest set, but better that a carbon set or the duraspark gold mag core set I also have.


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You can also go to a colder plus. You can get the EK plug in a heat range 6. You can buy the Denso equilivant at advanced auto.

I run the BKR6EKB-11 plugs in my Saturn and 2.5l Subaru. In my Saturn that plug is 2 heat ranges colder and totally eliminated most active knock retard.


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Yes, it does help with ping. I was running the recommend DENSO IK22 Iridiums which are two steps colder and was getting pinging too much. Switched to IK24's which are 3 steps colder and now there's less. Still there on hot days on a steep climb at cruising speed but mostly gone.

So guess what? The Magnecor's resistance was only 17 ohms! I was really surprised. Don't know why some people tested them out way higher. I am posting more data in my build thread.