Ngk bp5es bp6es

I asked…and received this answer …from NGK: …part numbers for BP6ES are 7333 for USA, silver box made in Japan: and 7811 yellow red box-made in France, EU and UK part number. The plugs…NGK says…are the same.
There are similar for BP5ES, the next step hotter, also has …two part #s…and for other plugs…do note however…some places automatically substitute the new BPR6ES…or BPR5ES , resistor plugs, with 5,000 ohms per plug, rather than 1,000 ohms. NGK says the BP5ES BP6ES is no longer being made…NOS can be found. All now replaced by the resistor…double check if buying on web. I did…and now have a life time supply. I don’t need no stinkin ohms.

What is the angst about having resistor spark plugs?

not much Paul…but when I have a choice of ohms, more, or less, in my ignition system, I choose less. I don’t need resistor plugs for any purpose that they provide. I run primary wires with very little resistance per foot, why then add a sparky with 5,000 ohms…when I don’t need it… Nick

What do you think you’re gaining?

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I don’t think, or know that I gain anything. I do know I do not need a resistor sparkplug, Jaguar did not fit them, if they even existed anywhere then, the spark plug wires then…were low resistance. Lucas coils are well known to overheat, and fail. Modern cars need it, modern cars have very high output coils, some with coils right at each plug. Why would I want to introduce resistance into a system that does not need it, never had it. I wouldn’t, so I don’t. If someone likes to listen to the radio while in a Jaguar…fine. If they pull up next to me…and Springsteen turns into zzzzzssst zzzzssssst oh well. Nick

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You know what? What is the effect of resistance on performance and why?

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not even the auto electrical engineers agree…I have read extensively…it depends…and is different for modern high voltage cars, with computers, that sense and read everything, and adjust, than it is for an old Jag with a Lucas coil and distributor. A performance difference could be slight in some cars, important in others. Resistance can either nano delay a spark but at the same time build current, or not…depends. I am not claiming, nor concerned about performance anyway…it may well be minor…could be an issue. I simply do NOT NEED resistance in the system…why would I need it? Did all the car manufacturers for decades overlook some need for it…? No…it was not needed til radios showed up. I don’t need ignition system resistance. Your turn now…tell me why I would want or need 5,000 more ohms per spark plug and who knows how many thousands of ohms (and it is in thousands per foot) in modern wires…I will wait here…

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So let’s do a test. Here are two different scope traces. Which trace is a low resistance secondary, which has a high resistance secondary?

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a scope test of what system…how much zap is the zapper putting out, and over what path, made of what does the zapper send the zap, did a computer intervene and adjust the zap? , C,mon man…I am not an auto electric engineer…but I know my car did not arrive from the factory with resistance wires or plugs…and there ain’t any in there now…I was waiting.past my bed time for you to tell me WHY I would need or want resistance…oh…I know you will say it builds a better spark…well 50% of the actual electrical whizzes say yes…and 50% say no…so what do you say… We have all been happy with Champion N8, N5C or N9Y, or N12Y, the NGKs…for years…now you will tell me it was all wrong?

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According to NGK they were introduced in the 1960, so the XK engine predates them.

From the NGK web site:

*At the moment the spark jumps the gap it causes a high frequency burst of energy, known as RFI (radio frequency interference). RFI, as its name suggests, creates static on your radio and interference with other electronic equipment, including the vehicle’s on-board electronic control units (ECUs). *

Resistor plugs were developed in the 1960s to suppress some of the spark energy, thus lowering RFI to an acceptable level. Most resistor spark plugs use a monolithic resistor, generally made of graphite and glass materials, to filter the electrical voltage as it passes through the center electrode.

Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. It is for this reason that most racing plugs are non-resistor types. However, in most automotive applications, a resistor plug is required for proper vehicle operation. Use of non-resistor plugs in vehicles that call for a resistor type can result in rough idling, high-rpm misfire, and abnormal combustion.

Using resistor, or non-resistor, plugs will make absolutely NO measurable difference whatsoever in performance. ZERO, ZIP, NADA, NONE. Using non-resistor plugs has NO benefit whatsoever, but absolutely can and will annoy other drivers nearby, by interfering with their radio reception, especially AM radio. Same goes for resistor wires.

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As I have asserted before, backed up by dyno results. However, it’s not old school.


hey y’all…I am not sayin…and never have…that there is a benefit to non resistor plugs…there however may be an issue…when adding the 5,000 ohms per plug when, IF hi ohm resistance wiring is also used…as modern car wiring is in the thousands of ohms per foot. Just sayin…resistor plugs are not needed…unless you listen to the radio…a travesty in an open Jaguar anyway. As John Walker posted from the NGK web site…there are some auto electrical engineers who DO think it matters…Nick

from NGK…(see…you guys not buying the non resistor plugs have caused this !!)

Thank you for your inquiry. The stock numbers are different for each market. 7811 is European market stock number but the part number is the same, BP6ES.
Unfortunately since the demand for non-resistor plugs are decreasing, the cost of production was out-weighing the sales so the decision was made to discontinue production of most non-resistor plugs.

Lela Martin

Racing Sponsorship / Technical Support – Aftermarket Division

NGK Spark Plugs (U.S.A.), Inc.
(877) 473-6767 option 2 |

There has been much discussion about the new EDIS system requiring resistor type plugs, much of the testing and write-ups coming from folks in the UK I believe.

I have a specific interest in this issue due to my trying for months now to nail down an idling problem. As you might recall I have the EDIS system, and used the MSD system before it. In both cases I had and still have the idling problem.

Given what John has found on the NGK site, what’s your view of non-resistor plugs possibly causing problems with the electronic ignitions systems I’ve mentioned?

Non-resistor plugs WILL cause problems with most electronic ignitions, and CAN cause premature failure of the electronics. On EDIS, even if it doesn’t fail, you are very likely to see missing, sometimes quite severe. I’ve experienced it myself, as have many others. Most electronic ignition systems warn that resistor wires and/or plugs MUST be used for these reasons.

And, for the Nth time, there is NO performance downside to using resistor plugs and wires. NONE.


RAY…whew…never ever said there was a downside…but for a standard points older system there is also no upside…all the ol cars ran on non resistor for ever. Y’all used to love N5C, N11YC…and the BP5 or 6 ES…now ya argue against em. And…add hi resistance wiring and you WILL have a problem . Granted…once anyone decides to modernize the ignition system…well then…other changes are required…, just to rattle the can…why stop with EDIS and resistor plugs, and the wires needed…power windows are nice, 5 speeds, Mazda seats, air conditioning. My old cars feel like they did back then and I now and then have to adjust or install points. But we have cooked this bad recipe before…lets leave it. Nick

I admit that I have not been following this thread too closely, but where is anybody arguing against the older plugs? I think I missed that.

yup. musta missed it…Nick

Ok… where?