Yeah, I have a DMCH headlight switch, so it's not bone stock. :nervous:Quote:
Originally Posted by stevedmc
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Yeah, I have a DMCH headlight switch, so it's not bone stock. :nervous:Quote:
Originally Posted by stevedmc
Here's what Ron is trying to explain…..
The spark plug will fire at whatever voltage is sufficient to bridge the gap.
If you have a coil that can produce up to 1.21 jigga-volts, but the air/mixture/etc breaks down at 25 volts, guess how much voltage is going across that gap? 25V.
Now, let's say you double that gap. If we wave our hands and summon magic (seriously, I don't feel like looking up the equations right now), we'll see that the voltage at which the spark occurs (breakdown of atmosphere) increases, because of the larger gap.
Simply increasing the gap WILL increase the voltage at the plug. If that voltage exceeds what your coil is capable of creating, no spark will happen.
The key to all this is just WHEN that breakdown occurs. Just putting in a higher voltage coil and a wider gap will not necessarily improve things without other changes.
The timing would probably need to be altered at best. Those modern engines running larger plug gaps also likely have much more intelligent electronics to fire things at just the right time.
Of course, ignore that last paragraph if you want. I'm not 100% sure that they are all doing that, but if your goal is maximum efficiency and performance, that'd be the best way. They also have lots of other new features…..
--buddy
No "intelligent electronics" in the 1970's (no moreso than the Bosch ECU).Quote:
Originally Posted by nullset
American manufacturers did advance ignition timing for emissions purposes in the 1970's, which led to increased chances of misfiring. That's where the larger diameter distributor caps came from -- to increase spark duration. Negative effects of advanced ignition timing are discussed in several places of the afore mentioned SAE paper (for example, p. 59 and p. 61).
DeLorean base timing was advanced from 10 degrees (Volvo North American spec on the exact same engine) to 13 degrees for the same reason -- to reduce emissions. Unfortunately spark duration was unchanged (Volvo PRV ignition is 100% identical to DeLorean ignition -- even the ECU's are identical). DeLorean owners may want to note Delco engineers' findings on p. 55: "Figure 22 demonstrates that the disadvantages of a short spark duration ignition system can be offset by increasing the spark plug gap..." There is little we can do to change spark duration, but the negative effects of advancing base ignition time 3 degrees can be offset by increasing plug gap.
BTW: My engine is timed 10 degrees BTDC, which is one reason my car is faster than the rest of yours. Note that my distributor is curved for that base ignition time -- it has a much more steeper advance curve than a stock DeLorean unit. Do not retard your ignition back to 10 degrees BTDC and expect the same results without also swapping out the distributor.
Historical curiosity: it appears that DeLoreans were originally supposed to be timed 10 degrees BTDC just like their North American Volvo cousins -- note Figure 28 on Page C:05:03 of the Workshop Manual. DMC did not piggyback on Volvo's PRV certification -- D19, D20, and D21 were used for DeLoreans' own certification. Apparently in the process ignition timing was advanced and the distributor was dumbed down. DeLoreans lack two major emissions devices present on Volvo B28F -- EGR and air injection.
Bill Robertson
#5939
I like how you take the one part of my post that I explicitly stated I didn't know whether it was accurate or not, and write a novel on why you disagree.Quote:
Originally Posted by content22207
You also didn't address the first part - the part where I explain why increasing the plug gap DOES increase voltage, as Ron indicated.
Debate technique: If you are found to be wrong on one point, quickly throw something else out there to distract the person you're debating with and keep moving constantly.
--buddy
I agree with your explanation of ionization.
The low compression, lean burn combustion chamber conditions that started in the 1970's, and which were very much present when DeLoreans were introduced in 1981, are counter productive to combustion. To offset these inhibiting characteristics, American and Japanese manufacturers adopted higher voltage ignition and widened the spark plug gap, which led to higher current ionization and better combustion. Some manufacturers also increased spark duration by enlarging the distributor cap and rotor.
Bosch stands virtually alone in keeping its spark plug gaps unchanged after the switch from breaker points to breakerless ignition.
I disagree completely with your assertion that HEI depends upon "advanced electronics" (your words. not mine) beyond basic breakerless ignition technology, and I disagree with your assertion that timing must be altered for HEI, both of which are as wrong as can be. Historical evidence such as Ford's Duraspark module compared the Bosch ECU disproves the former, and Volvo base timing compared DeLorean timing disproves the latter.
Bill Robertson
#5939
Sorry, I missed this one:Quote:
Originally Posted by stevedmc
No, I never thought that and have said quite clearly that widening the gap alone will increase the voltage all along because it is impossible to do, so I assumed you knew I didn't believe that part (My mistake). An honest mistake, but again, my mistake.
Quote:
Originally Posted by stevedmc
I just don't see the "without increasing the voltage" part.Quote:
Originally Posted by Ron
You flatly put words in my mouth...which contradicts something I said was impossible. Wow.
It seems to me you would get all of this from here.
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What do you call this?Quote:
Originally Posted by stevedmc
You quoted the above and posted.Quote:
Originally Posted by Ron
Looked like YOU were to me!Quote:
Originally Posted by stevedmc
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No. The debate was whether changing a coil alone would increase performance.Quote:
Originally Posted by stevedmc
and then on to include the definition of "performance" in this thread...Quote:
Originally Posted by Ron
I guess it is safe to assume you didn't mean it was "Wrong" that increasing secondary voltage increased energy at the gap, so, since you claimed it isn't from widening the gap and that it will not fire w/o increasing the voltage, I have to throw the question back at you. I already answered it anyway, again, widening the gap raises the voltage.
You don't know what you are talking about. You are not on the same page...- Show me where I said anything about changing input voltage...you began all this by saying it was wrong for me to say changing the plug gap would increase energy at the gap (OR by using a larger coil...surely you didn't mean it.)Quote:
Originally Posted by stevedmc
Are you skimming posts?
I'm sorry you were silly enough not to follow directions or change out several things at once back then. The rest sounds like you should of redone your wiring to begin with to me.
I have to admit, after decades as a mechanic, I don't have a lot of experience second guessing the engineers on this type of thing. So I'll shut the hell up.
The problem is the Bosch Blue coil does not produce an infinite supply of voltage. Quite the contrary -- it produces a very finite amount of voltage (about 18,000 volts max, IIRC). There *WILL* come a point where the plug gap can not be widened any further and the coil will be able to supply the voltage necessary to jump it. I suspect .026" is very close to that limit.Quote:
Originally Posted by Ron
Coil output is of course a multiple of input. Increasing primary voltage into the coil will increase secondary output voltage. Unfortunately the Bosch Blue coil does not seem to be able to handle more than 6-8 volts input, which does make sense when you consider that it was designed in the late 1960's when that was a typical coil supply voltage (due to breaker point limitations already discussed).
Rumor is that running more than 8 volts into a Bosch Blue coil for an extended period of time will damage it.
Higher winding coils (so called "performance" coils) produce more secondary voltage for the same amount of input voltage, simply because they have a higher ratio of secondary to primary windings. If you replace a Bosch Blue coil with a higher winding coil, you will be able to jump a larger plug gap, even with no other changes to the ignition system.
What Steve discovered was that his high winding coil also had a finite amount of voltage it could produce. He exceeded the gap that his coil could reliably jump, and started misfiring accordingly.
This is the crucial difference: his high winding coil was not limited to 6-8 volts input. By increasing the amount of voltage going into his coil, he could increase the amount of secondary voltage produced by the coil. The widened plug gaps that before could not be jumped reliably now were jumped regularly.
That is why we caution owners not to widen their plug gaps without also increasing primary voltage supply, even if they are running a higher winding coil.
I can't speak for MSD coils, but a Pertronix coil, with 12.5 volts primary voltage, definitely has no problem producing enough secondary voltage to reliably jump a .05" plug gap -- I do so every time I drive my car all the way to New York/New Jersey, or New Orleans, or Kentucky, or Florida next summer (these distances are cited merely to indicate the extended periods of time a Pertronix coil can operate off 12.5 volts).
Bill Robertson
#5939
And just what in that post do you think I didn't know (other than Steves experiences), what does any of it has to do with increasing the performance by changing the coil alone on a stock car and whether it is fair for you to not include emissions as a part of "performance"?
And last but not least, if increasing the plug gap doesn't increase voltage at the plug and a widened plug gap will not fire w/o an increase in voltage, how the hell do you explain worn plugs and wide gaps in a running engine.
[You can't have it both ways even if there are two of you. Do you really think I don't know that you too know (knew) what was going on..LMFAO]
Bullshit.Quote:
Originally Posted by content22207
I have it from more than one reliable source that widening it at all will not allow the spark to jump, because there will be no increase in voltage, which is required to make the longer jump.
:screwy: