Author Topic: NGK D8EA vs. Champion RA6HC  (Read 4175 times)

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Offline fmctm1sw

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NGK D8EA vs. Champion RA6HC
« on: September 11, 2012, 11:45:19 am »
I stopped by the local Autozone asking for D8EA plugs.  They had none and told me they had the equivalent in the Champion RA6HC.  I noticed the "R" right away and said, "That's a resistor plug, that isn't going to work for me."  The guy insisted that they were the the same because "that's what came up on the screen."  I had him look up another store that had D8EAs.  So am I right or wrong about this?  Resistor plugs and the 350F (stock coils) are a no-no right?
re: burnouts thread 
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Dude is that a tire ? or an O-ring..??

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Offline goldarrow

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NGK D8EA vs. Champion RA6HC
« Reply #1 on: September 11, 2012, 11:54:11 am »
A little while back I went to autozone and ask for valve lapping tool, the sale guy then asked me "what the F@$):& was that" yes literally with F word. Despite that, I bought the tool anyway, cut up rubber parts, used it to my need, put back in package, returned it few days later.

This is why I love sohc4 to death. Know what you are looking and know where to shop.

I ordered x22es-u along with other stuffs from amazon.com $10 shipped for set of 4

« Last Edit: September 11, 2012, 11:59:52 am by goldarrow »
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Offline dave500

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Re: NGK D8EA vs. Champion RA6HC
« Reply #2 on: September 11, 2012, 01:20:07 pm »
the R is for resistor type,,champion plugs belong in lawn mowers only.,use only ngk or denso.

Offline PeWe

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Re: NGK D8EA vs. Champion RA6HC
« Reply #3 on: September 12, 2012, 04:37:45 am »
« Last Edit: September 12, 2012, 05:15:17 am by PeWe »
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Offline Duanob

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Re: NGK D8EA vs. Champion RA6HC
« Reply #4 on: September 12, 2012, 09:00:50 am »
champion plugs belong in lawn mowers only..

Briggs and Stratton lawn mowers: yes

My Honda mower gets NGK.

AuotZone is a freakin joke as far as the people working there. They know nothing. I go to NAPA when I can. Or my local Carquest carries NGK D7EA plugs and oil filters to fit my bike. Everything else comes from the interwebs.
The only problem left on my bike is the nut that holds onto the handle bars! ;)

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Offline Jiminy Indy

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Re: NGK D8EA vs. Champion RA6HC
« Reply #5 on: September 12, 2012, 10:57:34 am »
Just for information sake, what does a resistor plug do that's not good for the engine. I think I knew at one point they introduced resistor plugs to reduce static and interference in car radios - but I could be all wrong. Just wondered what it fouls up on a non-resistor engine - I guess it's the same question that started this topic. Anybody know?
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Offline TwoTired

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Re: NGK D8EA vs. Champion RA6HC
« Reply #6 on: September 12, 2012, 12:48:03 pm »
Just for information sake, what does a resistor plug do that's not good for the engine.
Anybody know?
Yes, I know. 

The short answer is that is that a resistor plug is not bad for an engine in general.  Millions of engines use resistor plugs designed to use them.

The original SOHC4 design did not use resistor plugs, they used resistor plug caps, and were optimized with this feature in a specific quantity in the system.  Resistor plugs add more resistance to the circuit and alters the operating parameters.
To understand the full impact requires you understand how the original design worked.
(Lengthy description omitted.)

The result is that resistor plugs added to the SOHC4, reduce spark current while lengthening the spark event time,  and yield marginal spark heat and reliability when spark plugs wear, points deteriorate, and system voltages are low.
These are considered bad or "not good" for the engine's operational characteristics.

Any other questions?
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC

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Offline Jeff.Saunders

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Re: NGK D8EA vs. Champion RA6HC
« Reply #7 on: September 12, 2012, 02:10:36 pm »
You can also buy resistor plug wire as well.  Under no circumstances would you want to run more than one of the three resistor options.  If you do, you can create problems - esp. if you run electronic ignitions. 

While each company says their plug is an equivilent, the reality is there are differences in the heat ranges.  A few years ago, I had a detailed chart showing the Champion versus NGK plugs and there was a slight overlap between the different plugs.
« Last Edit: September 12, 2012, 02:12:22 pm by Jeff.Saunders »
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Offline TwoTired

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Re: NGK D8EA vs. Champion RA6HC
« Reply #8 on: September 12, 2012, 03:33:44 pm »
You can also buy resistor plug wire as well.  Under no circumstances would you want to run more than one of the three resistor options.  If you do, you can create problems - esp. if you run electronic ignitions. 

There are exceptions:
The CB550s had 10K? spark plug caps, for a total of 20K? in the coil secondary.  (Steel wire core leads and no resistors in the plugs)
The replacement caps available today are usually 5K?, which is half the original specification.  Spark plug internal resistance is usually 5K? for each instance.  So, 2 plug caps and two 2 R spark plugs would give the same 20K resistance as factory spec.

I will mention that at least some Canadian Cb750's specified both resistor plug caps AND resistor spark plugs.  (I believe the combo yielded the same 20K resistance, as mentioned above.)  American models had the same plug caps and no resistor plugs, for a 10 K total secondary resistance.

Resistance wire has an ohms/ft rating, which can vary from manufacturer to manufacturer.  If you are making your own, length used is important and it's installed value should be considered along with spark plug and plug cap selection.

The attached picture describes a spark event.  It is typical of all ignitions that employ firing spark plugs from stored energy in coils regardless if triggered by point contacts or electronic means.  (Other schemes of spark generation can also be employed, but only a very few modified SOHC4s use those schemes.)

1 is the point at which the spark arc actually begins.  It is determined by the spark gap(s) and the atmosphere conditions and contents between the electrodes.  Time period 2 is the event duration where current flows in the circuit.  Here is where the resistors have any influence in the coil secondary circuit.  Low resistance shortens the event with any given coil charge storage capacity.  (Spark is intense, but very short).  Higher resistance lengthens the event and reduces current flowing everywhere in the secondary.   Spark is not quite as hot, but there is more time to involve more of the contents pass by the spark electrodes.  High currents can induce coil heating and effect their longevity.   High currents deplete more of the energy stored in the coil which must be replaced before the next event. (This requires more power from the bike's electrical system.)  So indirectly, the spark resistance has some impact on the total draw from the bike's electrical supply.

Nice to have simple questions answered, no?

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC

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Offline Bailgang

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Re: NGK D8EA vs. Champion RA6HC
« Reply #9 on: September 12, 2012, 05:24:12 pm »
A little while back I went to autozone and ask for valve lapping tool, the sale guy then asked me "what the F@$):& was that" yes literally with F word. Despite that, I bought the tool anyway, cut up rubber parts, used it to my need, put back in package, returned it few days later.


I went to a local auto parts store that had a newbie behind the counter and told him I needed an oil pressure sending unit for my 70' Pontiac GP. He was leafing through a book and seemed to be hung up in the AMC section so I said "dude, it's a Pontiac" and he replied, "American Motors means the American made cars" (I'm not making this up) I said haven't you heard of Rambler or cars like the Javelin? All I got was a "huh?" look so I told him to keep turning the pages. Lo and behold once he got past AMC, Chevy appears then Chrysler and so on and his huh look went to "what the F..." as I tell him to keep turning the pages until he arrived at Pontiac.
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Offline killersoundz

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Re: NGK D8EA vs. Champion RA6HC
« Reply #10 on: September 12, 2012, 06:36:51 pm »
I purchased D8EA's at O Riley's. about 8 bucks for 4 of them.
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http://forums.sohc4.net/index.php?topic=107447.0

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Offline Jeff.Saunders

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Re: NGK D8EA vs. Champion RA6HC
« Reply #11 on: September 12, 2012, 06:51:32 pm »
TwoTired - good point.  Doubling resistance with aftermarket electronic ignitions is a bad idea.  We had a customer do this on A Kawasaki GPZ 1100 with bad consequences. 

The key is to match what the factory did on each specific bike unless there's reasons to change.

These days, I'm not sure if resistance helps or hurts.  I struggle to get my head around how ethanol has impacted this.  From all I've read, the ethanol mix in fuel slows down the combustion a touch - so does having a stronger spark help, or would a slight delay on the spark help fully ignite the fuel charge in the cylinder.   Hmmmm... 
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Offline Jiminy Indy

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Re: NGK D8EA vs. Champion RA6HC
« Reply #12 on: September 13, 2012, 04:38:24 am »
So (ahem) for the electrically-challenged amongst us, if I understand this correctly you could run the higher resistance plugs without an immediately noticeable change in performance (say you were stranded somewhere and AutoZone (shudder) was the only available place or plugs). Longer terms it shortens coil life & point life and you won't get optimal performance, but you "could" run them for a bit if necessary without, say blowing up your engine or causing irreparable harm, correct?

Obviously from above not something you would want to do, but something you could do if the situation dictated.
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Offline kslrr

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Re: NGK D8EA vs. Champion RA6HC
« Reply #13 on: September 13, 2012, 08:34:03 am »
...These days, I'm not sure if resistance helps or hurts.  I struggle to get my head around how ethanol has impacted this.  From all I've read, the ethanol mix in fuel slows down the combustion a touch - so does having a stronger spark help, or would a slight delay on the spark help fully ignite the fuel charge in the cylinder.   Hmmmm... 

The ethanol slightly increases the Octane rating which means that the timing could be advanced slightly, though the over all Octane rating of the gas has not changed, so any changes in the timing would be mute.
« Last Edit: September 13, 2012, 08:37:02 am by kslrr »
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Offline TwoTired

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Re: NGK D8EA vs. Champion RA6HC
« Reply #14 on: September 13, 2012, 12:09:40 pm »
So (ahem) for the electrically-challenged amongst us, if I understand this correctly you could run the higher resistance plugs without an immediately noticeable change in performance (say you were stranded somewhere and AutoZone (shudder) was the only available place or plugs).
Yes

Longer terms it shortens coil life & point life
No, just the opposite.


and you won't get optimal performance, but you "could" run them for a bit if necessary without, say blowing up your engine or causing irreparable harm, correct?

Yes. Probably won't notice a performance hit until there is plug and point wear.  So, with the SOHC4 you would need to address plug replacement and point attention at shorter intervals than book values to maintain performance.  (In the instance where too much resistance has been added to the ignition secondary).

At the plug, spark leaps from the sharp edges more readily than the flat, smooth areas, and it takes less voltage to do so.  As the plugs wear, there is spark erosion of those sharp edges, making them smooth.  To get the same spark activity, a higher voltage is needed to create and maintain the spark intensity and duration of time.  So, plugs are more prone to end of life misfires as they get used up and tax the ignition system capability. 

With the points, it is all about time, and the ability to charge up the coils.  Point surface degradation and rubbing block wear alter the energy storage time of the coils.  This timing becomes more critical at high RPMs when time between firing event becomes shorter.  This is where to expect misfires or loss of power due to inadequate ignition strength and duration and why the tune up intervals are specified, to keep the engine power near peak levels.

Compare the coil to a bucket of water.  The spark plugs dip a ladle full out of it on a regular basis.  The resistors in the secondary determine the size of that ladle.  RPM is how often the ladle is dipped.  The point timing dwell angle, determines how much water is put into the bucket (coil).  The goal, of course, is to never let the ladle retrieve less than a full measure.

Traditionally, the spark resistors in the output have been described as reducing Radio interference, which it does, as well as having other benefits.

When current passes through a wire it creates an electromagnetic field around it, in a radiation strength relative to the voltage and current passing through it.  Since we need high voltage to jump a spark gap, small changes in the current make a large impact on the radiation strength emanating from the wire.  This energy is lost to the ignition circuit and simply thrown away.  The resistors reduce the current, which reduces the lost energy.  Since the spark is pulsed on a repetitive cycle, the power and frequency can confuse receiver than are sensitive to those frequencies, particularly when the the power arriving from a transmission station is weaker than the power coming from ignition wires.
Traditionally, radio interference was a major concern.  However, with the integration of very low voltage computer equipment (some of these devices operate on 1.2v), any wire in proximity to a radiation wire becomes a receiver antenna that absorbs and transfers power to whatever is attached.  Noise spikes at computer equipment can either confuse it to make it operate unpredictably, or if the power received is large enough, destroy transistor junctions and render it permanently inoperable.

In this way, ignition resistors provide a dual benefit of improving spark AND protecting nearby sensitive equipment.  Both are important considerations.

Hope this helps,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC

Popeye: "Wrong is wrong, even when it helps ya."

Offline Jiminy Indy

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Re: NGK D8EA vs. Champion RA6HC
« Reply #15 on: September 13, 2012, 01:14:30 pm »
Makes perfect sense.

Thank you sir - great explanation.
Of all the things I've lost, I miss my mind the most.

"Shot up the alley and then cut across the street" - now that's some violence you can appreciate!