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maybe it’s a language difference, but I’m not understanding your replies at all. Otherwise it seems to me that you’re mixed up or don’t have the proper understanding. I’m fairly certain that the dwell settings you listed are not exceeding the overall duty cycle limit if that’s what you’re getting at.
I've just been playing around with the values and all info I find tell me that the IGN-1A coils can stand some more duty cylce than the OEM coils. I guess they do their job using the OEM dwell setting but doing this they get a lot less charging time than the suggenstion by AEM. I did not measure primary current though, so I cannot tell which dwell would be the suggested from the table you posted. Still, lokking at the lowest 4A and 14V there is 2,3ms. The OEM table provides this charging up to 6000rpm, thereafter the coil is limited by dutycyle and the dwell goes down to 1,5ms at 9000rpm. Using a dutycyle limit of 32,5% the coils could still be charged 2,2ms at 9000rpm (14V). To be honest, I don't know if there is a benefit from this, I'd guess there will be a stronger spark chnaging the coil longer but obviously the spark is strong enogh even with the OEM dwell.
I just tought there is no reason not to use the capability of the hardware a little more by bringing them closer to the window they are supposed to work in.
This is why I made the spreadsheed. It lets you enter a base dwell you'd like to see at a specific voltage. It then sets this dwell value under the condition the maximimum duty cyle is not busted (you can enter that as well, in this case the value represention the max duty is set) and the value is not lower than the OEM value (in this case the OEM value is set). My original question was how the voltage affects the dwel. What I used in the table is a linear approch, so if dwell should be 2ms at 14V, it would be 4ms at 7V as an example. From the table you posted I can see, that this is not true. The relation is not linear, looking at the 4A row the dwell is 1,9ms at 16V, but it is not 1,9Vx2=3,8ms at 8V, it is 4,6ms. I could probably fit a function that can make the voltage adjustment based on this data. On the other hand I don't really get why voltages as low as 7V are important in this table. This could only be factor when starting the engine from battery maybe. The only 2 rows that should be important for normal engine operation should be the 14V and the 12,75V rows I guess.
Anyway, I flashed dwell setting for a 3ms target at 13,9V now using a maximum duty cycle of 32,5%. So fare no problems, the map looks like this now (upper part is ms, middle duty cycle and bottom is raw data values for Mazdaedit):
I just did not want to go up to the limit AEM specifies (40%). So I left 7,5% to this leaving more time for the coils to cool off.
7,5% is quite random though, I could have chosen 5 or 10 as well.
3mS is more than enough for those coils NA, but possibly your numbers are off some because values greater than 3.5mS would not be so unusual for a turbo rotary application given certain conditions.
even then you can use quite a bit more in certain areas where it might be applicable because in general it’s not likely going to be on that high load map cell setting for an extended period of time. It will be moving and changing with rpm/load. Well depending on the ecu and dwell map type and values any way.
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The coils are AEM smart coils (30-2853). It's my understanding that these are IGN-1A, just labeld by AEM.
Driving the car on track means usually spending the most of the time in the +6000rpm range where the coils are typiclly limited by duty cycle in the normal 14Vish V range. AEM gives this information for the coils:
TECHNICAL SPECIFICATIONS
Output (no load): 40kV minimum
Output (50pF load): 40kV +/- 10%
Output Energy: 103 mJ +/- 7%
Peak Secondary Current: 102 mA +/- 10%
Arc Duration: 2.9mS +/- 10%
Turns Ratio 71:1
Maximum Current: 19 Amps
Maximum Battery Voltage: 17 Volts
Base Dwell: 3.0 mS
Max Continuous Dwell: 9 mS but don’t exceed 40% duty cycle
Max Intermittent Dwell: 80% duty cycle, 5 seconds maximum
Mating Connector: Packard/Delphi 12162825 “Pull to Seat”
Mating Contacts: Packard/Delphi 12124075 “Pull to Seat”
High Tension Wire Terminal: HEI “spark plug top” Style
This is why I intended to stay below 40DC and 9ms dwell (plus some margin). The rather high dwell values in the lower rpm range came from the OEM dwell map. I didn't see a reason to drop dwell below the OEM values as this does neither violate max dwell nor mac DC provided by AEM.
Of course I could up everything to 40% DC but I'm not sure if there would be a benefit running the coils at their continious level of DC and put more stress on them if as mentioned they run on the OEM map with a max DC of 23% as well. So I guess the 32,5% I choose for the time beeing is a compromise between these two...
You’re way overthinking this, many people have been using these coils on rotary engines for over many, many years.
The IGN-1A coils were specifically designed for high rpm use on Mercury 2-stroke boat racing engines. That’s why they make great rotary engine coils. Your duty numbers are off a lot, not that it really matters.
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Where you’re off is that you only considered the Time duty factor, but it’s not just time. There are other duty factors as well, such as Amperage. That’s why you can safely run higher values at low supply voltage etc.
You have some basic misunderstandings. Per the specs below the 40% limit is at the max recommended continuous value of 9mS. You can see how that changes in the next spec for max intermittent limit:
Max Continuous Dwell: 9 mS but don’t exceed 40% duty cycle
Max Intermittent Dwell: 80% duty cycle, 5 seconds maximum
So these also have to be considered, which is where the chart I posted previously comes into play
Maximum Current: 19 Amps
Maximum Battery Voltage: 17 Volts
Lance Nist at Pantera EFI is the source supplier of the IGN-1A coil to all the other sellers, and more or less the guru for them as well. He has already confirmed that these coils will be within the rated duty cycle for 5 mS @ 9000 rpm on a rotary engine. Though that’s fairly close to the limit. The dwell rarely needs to be that high for pretty much most; if not all, the applications on this forum though.
So if you go back to where I stated that 3.5mS is likely about all anyone here will ever need, and that 3mS is way more than enough for an NA Renesis, then you likely will never need to be concerned about exceeding the coil duty. Because nobody is going to spinning any 13B engine high enough under ignition loading to worry about duty with dwell down in that range. That would only occur with higher dwell settings (or extreme voltage).
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Ok, so I could run more dwell. On the other hand the engine does alright well on the OEM dwell setting with these coils also. Whats the benefit of pushing the coils to their limit on a NA application?
I just did not want to go up to the limit AEM specifies (40%). So I left 7,5% to this leaving more time for the coils to cool off.
7,5% is quite random though, I could have chosen 5 or 10 as well.
spark event is also part of the duty cycle. coil work equally hard producing spark as discharging. its negligible on low ignition frequency but at high rpm, it is very important and alters the calculation a lot
I certainly pushed the GM coils to the limit, both dwell and sustained rpm limiter stalling … probably might tone it down some today except immanevergonna run those coils again.
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07-08-2022, 02:42 PM
