Originally Posted by Norbie
i think youll find that because C16 is highly leaded it ignites very easy,
i found the difference from running the old avgas to modern unleaded fuel to be significant even though the avgas had more octane
i knew what you were saying - each coil fires twice for each 720 degrees of crank rotation ... my point was that the time to charge (e.g. the 3.5m/s dwell for YelloRolla's setup) and then to discharge it (~1 m/s) is short compared the duration between ignition events in a running engine, e.g. a 4cyl engine at 8000 rpm has ~30 m/s between each waste-spark coil firing.
When you consider that a coil attached to a old-school v8 will fire 8 times during 720 degrees of crank rotation - and does this with relative ease, ergo the waste-spark coil isn't being worked super hard.
But as you point out, the less work load (e.g. CoP would be 60 m/s between sparks) the greater time you have for the coil to dissapate any excess heat.
Originally Posted by Norbie
i think youll find that because C16 is highly leaded it ignites very easy,
i found the difference from running the old avgas to modern unleaded fuel to be significant even though the avgas had more octane
a fool remains undescovered untill he speaks!
Yes, but this coil will be large, relatively speaking, and located in an area with plenty of airflow, as opposed to COP whose location is generally pretty hot, which would suggest a lot of thermal stress.Originally Posted by thechuckster
Everything has a lifespan. If you're running the coil twice as often, you're reducing that lifespan. If the coilpacks are designed for the lifespan of a factory engine (only ever heard of cop coils failing on modified engines), then running them in wasted spark will probably have no bearing on their longevity in the relative timeframe that you're likely to own the vehicle (if you don't care about what happens with the car after you sell it - as far as I understand none of us are building cars to last 20-30 years).Originally Posted by thechuckster
Wasted spark also means you don't need to run a multiplexor (should your ECU not have the desired number of ignition outputs) which is another component that can fail (and possibly more likely to fail than a coil).
My personal preference would be run the 1UZ coils sequentially, however nobody in the industry considers this mandatory (as long as it runs wasted spark), thus no one will put any effort into achieving this of their own volition. If you specifically ask for it, they'll lose respect for you and almost ridicule you and your opinion.
Mos.
Admin, I.T., Founding Member, Toymods Car Club Inc.
2000 IS200 Sports Luxury 1UZ-FE VVTi, 1991 MX83 Grande 2JZ-GTE (sold)
Hi!
Reactivating this topic!
Can someone refer to some scientific research or, at least, some dyno measurements, that shows if there´s engine efficiency variation between wasted spark and sequential ignition systems? I´m focusing specifically in results related to these two firing configurations, supposing the same other parameters (ignition discharge energy, output voltage, spark plug electrodes gap, compression ratio, A/F ratio and so on).
I can't help you with any research results, and I doubt if any exist. Wasted spark fires each cylinder in the same order and at the same timing as sequential ignition. The only difference is that wasted spark produces an extra unused spark that contributes nothing to the combustion process. Where all other parameters are equal, the results will be equal.
Here is a link to a somewhat related topic... http://www.adaptronic.com.au/forum/i...22575#msg22575
Cheers... jondee86
Hi, jondee86. Thanks for your comments.
I´ve real all that topic on Adaptronic forum but unfortunately it doesn´t provide any data about my quest. "Condition #3" that user Andy mentioned on his first post is dispensable, since a hypothetical subdimensioned and/or defective wiring won´t be a reason to keep a wasted spark configuration. The solution for a problematic wiring is make a proper wiring! In addition, in a sequential approach, one coil is charged at a time, as it happens when a doubled output coil is used. The doubled current consumption would happen if individual coils were used in a wasted spark configuration, since two coils would be driven, making worst the voltage drop that Andy mentioned due some hypothetical problematic wiring.
There are some specific scenarios that require or strongly recommend sequential ignition approach, but I won´t mention them here, since I am focusing on some hypothetical engine efficiency difference related to wasted spark and sequential ignition usage. If someone is interested on such scenarios, feel free to ask me.
As we all know, car makers apply effort to save production cost, even on high end cars. So, they won´t let cost raise regarding ignition subsystem for nothing, and sequential ignition system is more expensive then wasted spark one. Again, if someone is interested to know why, I can explain. Thus, I suppose that, except for those specific scenarios I mentioned above, makers will always opt for wasted spark configuration IF NO BENEFIT exist with sequential ignition approach.
I look forward and I will appreciate comments.
Last edited by sraposo; 08-01-2018 at 02:48 AM. Reason: Mispelling
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