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Thread: Sequential or Waste spark?

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    Deal with the Frog Backyard Mechanic Cool1's Avatar
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    Default Sequential or Waste spark?

    Ok ladies and germs. I now have my engine running so its time to choose some Coils and Igniters for perminate use.
    With the setup I am currently using, I am able to run sequential or waste spark. My question is, is there anything to gain by going sequential? I understand that with a stock engine there'll most likely be no gain at all, but what about later on once I upgade turbo and try and gain every little bit?
    I dont want to go the cheap now and then have to fork out again later on to upgrade

  2. #2
    Junior Member Too Much Toyota
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    Default Re: Sequential or Waste spark?

    sequential lets you run fatter CDI spark, waste-spark simplifies your control circitry (only one crank signal required).

    Unlike seqential injection which mostly benefits idle and cruise (with reduced emissions as a spinoff), sequential spark will give most of its benefits at very high rpm+boost (when you are most going to need good dwell time and a fat CDI spark).

    Is motor a drag motor or general flog-mobile?

    personally, my MSnS will run either and i like the simplicity of waste-spark. One side-effect of waste-spark is the 'wasted' spark helps clean the plug, particularly if you are running uber rich or have lots of burnt oil vapour.

  3. #3
    Deal with the Frog Backyard Mechanic Cool1's Avatar
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    Default Re: Sequential or Waste spark?

    The car will start off as a road rally car but will then become more drag orientated.

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    Toymods Club Member Backyard Mechanic Big T's Avatar
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    Default Re: Sequential or Waste spark?

    There was a decent thread about this in the old forums here :

    http://forums.toymods.org.au/index.p...t=0#msg_717037

    I too would be interested to see peoples' opinions about this seeing as i have to decide on an ignition system soonish.

    Eddie.
    4agte finally completed. 234rwkw @ 8125rpm. Tis fun

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    i wrote the Automotive Encyclopaedia roadsailing's Avatar
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    Default Re: Sequential or Waste spark?

    I was always a big advocate for one coil per plug, and i still am on NA engines.

    depending on your setup, you could use coil on plug for a neat looking setup, or individual remote coils for durability (coil on plug can be prone to overheating)

    apparently wasted spark can give you a bit of a power increase with a turbo engine, igniting CO exhaust or something. dont know too much about it.

    The "wasted" spark won't suck too much energy, as the electical resistance of the plug gap is a lot lower than on the compression stroke, so less current will flow accross it.

    I wouldn't bother with CDI, a decent electronic ignition should be all you need.

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    Deal with the Frog Backyard Mechanic Cool1's Avatar
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    Default Re: Sequential or Waste spark?

    I dont know the difference between CDI and HEI Anyone care to explain?

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    i wrote the Automotive Encyclopaedia roadsailing's Avatar
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    Default Re: Sequential or Waste spark?

    HEI = high energy ignition

    CDI = capacitive discharge ignition

    basically a conventional system (HEI i guess) uses a coil to store energy, wheras a CDI system uses a capacitor to store energy.

    CDI gives a higher energy spark, but for a shorter duration of time (which can cause problems in some instances).

    AFAIK in practise there is not enough of a benefit to use CDI, its much better than points ignition, but not that much better than electronic ignition.

  8. #8
    Deal with the Frog Backyard Mechanic Cool1's Avatar
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    Default Re: Sequential or Waste spark?

    Ahhh ok. Thanks boss.

  9. #9
    Current UZA80 owner Chief Engine Builder JustCallMeOrlando's Avatar
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    Default Re: Sequential or Waste spark?

    I with agree with all the details outlined above. Do you already have an ECU capable of running either setup? If so, why not go sequential?
    Teh UZA80 - Project Century - Remotely p00'd by association

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    Default Re: Sequential or Waste spark?

    Yes I have a setup that capable of either. So sequential it is!

    Next question, what coils and igniters?

  11. #11
    Junior Member Too Much Toyota
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    Default Re: Sequential or Waste spark?

    you'll need to determine if the ECU can do dwell control, or requires the igniter to do that, then acquire the appropriate over-priced bosch (or rebadged bosch part) to do so.

    Coils? there was another thread about coil-packs recently?

  12. #12
    Roadhouse Automotive Encyclopaedia emp?'s Avatar
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    Default Re: Sequential or Waste spark?

    i know with my setup its starting to blow the spark out, im looking into ways to fix that at the moment, anyone have any ideas? im running sequential now with bosch coils on a microtech lt12x ecu

  13. #13
    Junior Member Too Much Toyota oldcorollas's Avatar
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    Default Re: Sequential or Waste spark?

    are the coils getting enough charge time to saturate them at the moment? what is the dwell set to?

    normally dwell is what? 3ms? but being sequential, you can use more (with possible damage to coil? then again, dumb ignitors have longer dwell anyway..)

    you could try upping the dwell time briefly to see if it fixes the blow-out prob, but apart from that... higher voltage at coil? different coil with larger step up in voltage? resistance of wires and plugs will not make much difference if they are in good nick..
    "I'm a Teaspoon, not a mechanic"
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  14. #14
    Roadhouse Automotive Encyclopaedia emp?'s Avatar
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    Default Re: Sequential or Waste spark?

    can you adjust the dwell on the microtech? i got no idea
    the coils are hec715's with new eagle 8mm leads which are about 10cm long and iridium plugs, i was thinking maybe spitfire coil on plugs might be better?
    this is when the boost starts getting above 24psi so its not a huge problem just yet

  15. #15
    Junior Member Too Much Toyota oldcorollas's Avatar
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    Default Re: Sequential or Waste spark?

    i have no idea, but coil dwell should be something that is settable on all ECU's.. unless you have smart external ignitors that take care of the dwell time for you??

    if it has internal coil drivers, it should have either dwell time, or current limiting.... one of the two... i hope

    24psi?? ahh, so only a problem when driving to the shops?
    "I'm a Teaspoon, not a mechanic"
    "There is hardly anything in the world that a man can not make a little worse and sell a little cheaper" - John Ruskin (1819 - 1900)

    AU$TRALIA... come and stay and PAY and PAY!!! The moral high horse of the world!

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