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Coil Dwell Disassem and Denso Coil Behavior

 
Old Jul 8, 2015, 07:45 AM
  #16  
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Great stuff, being a percentage of cycle time makes sense. Seemed like it was some fixed value when I was looking at it years ago but the way you explain it makes much more sense.

Glad I went for the 16AWG wire when I did my harness for the coils with a dedicated relay and wired straight from the battery. Sounds like I'll be overcharging them with factory dwell settings now though.

I believe one of the benefits of the densos is their quick dwell time. Faster saturation also means a faster discharge time. Two 50mJ coils but one with a shorter discharge time means it's got a hotter arc/higher voltage output, which IMO is the most important aspect of a coil on a turbo motor.
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Old Jul 8, 2015, 09:29 AM
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Originally Posted by absolut525 View Post
Would there be any gain from tuning the ECU with stock coils?
I used to live in Astoria Oregon. Not too far from Portland. Im moving up to Alaska in a couple months.
Yes. I used modified dwell settings to run 40psi in my 2.4 on stock coils and a reasonable plug gap with factory plugs.
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Old Jul 10, 2015, 11:18 PM
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Very nice work as usual.


Originally Posted by SR Concepts View Post
I moved to Oregon because the weather is what I missed from England
Most people miss bacon or Marmite, but never the weather!
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Old Jul 11, 2015, 07:23 AM
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I am new to my evo having only owned it for about a week now, but from my gvr4 days, the original configuration of the coils is wasted spark, so when we converted to COP on those, it was literally coil on plug, but they were dual fired still. My evo9 came with a nice looking cop setup from the previous owner but I believe it is still the same conversion method where it dual fires.

How does this affect the performance of the coils as they are used in this topic?
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Old Jul 11, 2015, 08:11 AM
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Originally Posted by TrendSetter View Post
I am new to my evo having only owned it for about a week now, but from my gvr4 days, the original configuration of the coils is wasted spark, so when we converted to COP on those, it was literally coil on plug, but they were dual fired still. My evo9 came with a nice looking cop setup from the previous owner but I believe it is still the same conversion method where it dual fires.

How does this affect the performance of the coils as they are used in this topic?
Wasted spark means the COPs fire 2x more frequently than sequential, but the Toyota Denso coils seem to be able to handle it just fine. The more universal issue with any COP on the Evo that maintains wasted spark is that the power wiring to the coils is undersized. Increasing the dwell time seems to work as a solution but I could imagine that it could put some load on the wiring if run at high rpm for extended times, e.g., circuit course.
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Old Jul 13, 2015, 06:51 AM
  #21  
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Originally Posted by burgers22 View Post
Very nice work as usual.




Most people miss bacon or Marmite, but never the weather!
Well I have both those
As well as all the canned British beans I could ask for

The weather part comes from me living in California for a while and seeing it rain 1 time a year...much too hot.

Sorry off topic
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Old Jul 21, 2015, 07:20 PM
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Another great finding from Mychailo! Thanks!

I just substitute some addresses for 94170715 using the previous map value:

<table name="Ign Coil Base Dwell-Time" category="Ignition - Coil Dwell" address="41ea" type="2D" level="2" scaling="CoilDwellTime">
<table name="Battery" address="65ec" type="Y Axis" elements="9" scaling="BatteryVoltage"/>
</table>

<table name="Ign Coil Dwell-Time Reduction Start RPM" category="Ignition - Coil Dwell" address="1746" type="1D" level="2" scaling="RPMLimit"/>

<table name="Ign Coil Dwell-Time RPM Reduction Factor" category="Ignition - Coil Dwell" address="41fa" type="2D" level="2" scaling="Percent256-8">
<table name="Battery" address="65ec" type="Y Axis" elements="9" scaling="BatteryVoltage"/>
</table>

<table name="Ign Coil Dwell-Time Upper Bound" category="Ignition - Coil Dwell" address="420a" type="2D" level="2" scaling="CoilDwellTimeUpperBoundPercent">
<table name="Battery" address="65ec" type="Y Axis" elements="9" scaling="BatteryVoltage"/>
</table>

<table name="Ign Coil Dwell-Time Cranking" category="Ignition - Coil Dwell" address="41ea" type="1D" level="2" scaling="CoilDwellTime"/>

<table name="Ign Coil Dwell-Time Cranking Upper Bound" category="Ignition - Coil Dwell" address="420a" type="1D" level="2" scaling="CoilDwellTimeUpperBoundPercent"/>


I was trying to set up dwell time for Spoolinup COP installed at JDM EVO 8, and I tried 2.5ms dwell time I saw online, and reduced the dwell to ~2.5ms to minimize heating of coils, but surprisingly it gave "weaker feel", so I changed back to stock setting, and it was good again.

I didn't know why that time, but Mychailo's wiring limit theory makes perfect sense. So can it be improved by reporting this to Matt @ Spoolinup so that he can change the COP wiring to a thicker wires? or upstream wires also need upgrade? or even separate relay + direct battery wiring (mentioned by 03whitegsr) is needed?

As for EVO 7 coil being hotter than EVO 8 coil, Part catalog says, from later version of CP9A (I guess EVO VI), they use MD363552 and EVO IV~V uses MD321461, but it is now superseded by MD363552, so I don't think we can get earlier, "possibly hotter" coils any more. EVO IX uses different part number, but I guess that is because of difference spark plug and boot they use.

Some local EVO guys use Hyundai Sonata (Sirius engine) coils because they are way cheaper to get (Mitsubishi pulled out of this country ), only difference is two bolt holes rather than three. Not sure it is hotter than EVO stock coils though.

Last edited by ace33joe; Jul 21, 2015 at 08:14 PM. Reason: Address edit
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Old Jul 21, 2015, 10:13 PM
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Thanks for doing 9417. A heavier gauge wiring solution would be a nice feature, but its not absolutely necessary. For the rpm range we run, the main issue with stock wiring is that it might get a bit warm, or even hot. A heavier gauge solution would eliminate this issue. Coil output would be the same either way as long as the dwell was increased for the stock wiring as noted in one of my earlier posts.
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Old Jul 22, 2015, 01:04 AM
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Originally Posted by mrfred View Post
Thanks for doing 9417. A heavier gauge wiring solution would be a nice feature, but its not absolutely necessary. For the rpm range we run, the main issue with stock wiring is that it might get a bit warm, or even hot. A heavier gauge solution would eliminate this issue. Coil output would be the same either way as long as the dwell was increased for the stock wiring as noted in one of my earlier posts.
Thanks for your additional advice and explanation.

I thought reducing the dwell time can also extend "cooling" time at higher rpm, but as you pointed out, unless it is kept high rpm at racing event, it may make little difference to coil longevity.

I might suggest wire upgrade to local racing EVOs with Spoolinup COP.
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Old Jul 22, 2015, 01:08 AM
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Oh BTW, since stock EVO 8 coils flows less current, can I expect it to be fully charged with about 3.6ms dwell time according to the graph shown above?

I might set it up to maintain that dwell time upto 7k rpm then taper down with stock rate.

Hope I can squeeze max out of the current ignition system.
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Old Jul 22, 2015, 08:56 AM
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Originally Posted by ace33joe View Post
Oh BTW, since stock EVO 8 coils flows less current, can I expect it to be fully charged with about 3.6ms dwell time according to the graph shown above?

I might set it up to maintain that dwell time upto 7k rpm then taper down with stock rate.

Hope I can squeeze max out of the current ignition system.
3.6 ms is a good start for the stock coils, but the coils might not be able to handle it for extended periods. I've read that when coils overheat, the output can be reduced, and of course, they could fail in the long run. If you increase to 3.6 ms, definitely keep notes on how how power feels at high rpm at first and after a several laps.
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Old Jul 22, 2015, 06:01 PM
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Originally Posted by mrfred View Post
3.6 ms is a good start for the stock coils, but the coils might not be able to handle it for extended periods. I've read that when coils overheat, the output can be reduced, and of course, they could fail in the long run. If you increase to 3.6 ms, definitely keep notes on how how power feels at high rpm at first and after a several laps.
Do you think I should start with stock 3.46ms setting? I know once it is fully charged it is basically heating up the coil with max current, so even .x ms can make the difference in coil overheating.

I need to do 20min track sessions in ~90F summer days, so I may play it safe.

Thanks again for your advice.
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Old Jul 22, 2015, 07:11 PM
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Originally Posted by ace33joe View Post
Do you think I should start with stock 3.46ms setting? I know once it is fully charged it is basically heating up the coil with max current, so even .x ms can make the difference in coil overheating.

I need to do 20min track sessions in ~90F summer days, so I may play it safe.

Thanks again for your advice.
If you mean 3.46 ms across the rpm range, then sure. Not a big deal if you fry a coil, so can't hurt to experiment.
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Old Jul 22, 2015, 07:23 PM
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Originally Posted by mrfred View Post
If you mean 3.46 ms across the rpm range, then sure. Not a big deal if you fry a coil, so can't hurt to experiment.
Haha, Frying a coil on track might not be fun. I will try a bit more conservative reduction at high rpm. Thanks for advice.
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Old Sep 25, 2015, 07:10 PM
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Hey MrFred. Any chance of reposting the tables for 8859 from post 1. The EvoM code bug won't allow me to see it and a fix doesn't seem to be available. Not sure if there's some way of posting it up thay allows it to be seen, maybe a pm, hopefully there is. Thanks.
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