Experiences - Comparison "new" Rotax spark plugs vs NGK

Mike Wylde wrote:

Rotax Wizard wrote:

Hi all

Perhaps this thread has run it's full course.  Seems to me that nobody cares what facts are anymore.  Simple truth is Rotax can't sell you NGK and can't support NGK because NGK forbids it.  Simple enough?  You can put in a tractor plug if you want, it is completely up to you.  The only spark plug supplier, for the aircraft engines, is the Rotax private label plug.  

And yes in 2017 Rotax had to change the head on the type 582 to fit the new smaller thread Rotax plugs due to the above noted NGK refusal to allow their plugs to be used.  There is an SI on it under the  582 bullitians.  

Cheers

The above post is irrelevant to this discussion which is about whether the new very expensive plugs confer any advantages or disadvantages.

The fact of the problem with NGK did not force Rotax to change the style of plug. Presumably whichever manufacturer does now make the plugs for Rotax could have instead produced equivalents for the NGK types used which are simple basic traditional plugs.

For example, Champion list their type 809 as equivalent to the DCPR8E.  See

https://www.championautoparts.com/find-my-part/Part-Number-Results.html?part=dcpr8e and

https://drivcat.com/overlays/part-detail.aspx?brandId=CP&pNum=809&partType= 

Not sure I would agree with Mike's statement above...  The new plugs absolutely DO offer at least ONE advantage:  Rotax is able to build and deliver an aviation engine, complete with spark plugs, without breaking their supply chain for their non-aviation (much larger) business lines.

My understanding was that NGK basically came to Rotax, and told them that if they continued using the plugs in aviation engines, NGK would no longer supply plugs to Rotax.  The reasons for doing so are probably product liability related, but NGK has not explicitly stated that, and of course Rotax cannot speak for NGK, so we may never know for sure... 

In the end, what we know for sure is that Rotax is no longer using NGK plugs in their aviation lines, and NGK is still supplying plugs for Rotax's many non-aviation engines.  

As for the high price of the new Rotax plugs, I'm sure the relatively low volume has a large impact on the ability to amortize the cost of the manufacturing facility...  

All that said, I'm using NGK plugs in my 912 ULS.  Regardless of NGK's position on the matter, those are the plugs the engine was designed to use, and will continue using them as long as they are available at reasonable cost.

@James - if that is an advantage, it would be equally applicable if the new plugs branded Rotax were equivalent to the NGK plug (and the compatible ones from Champion/Autolite etc), they don't need to be different for the sake of it.

Of course an advantage to Rotax is that they can charge a lot more for a differentiated product.

In my post I should have said "advantages or disadvantages TO THE USER."

Dear forum community,
the original question was if there is any experience comparing NGK and Rotax spark plugs. Please screw the NGK in your newer Rotax engines (if Rotax spark plugs are installed) and report if there is a difference. Also pay attention to the ignition circle check. I have noticed it and I fear that the Rotax spark plugs will shorten the life of some Rotax types in the long run. Only if you really compare you will notice the difference.

Regarding the story "NGK no longer supplies Rotax". This is the official statement from Rotax. Even if a story is told a thousand times it will not be true. Of course Rotax is supplied by NGK (who gives up sales if there is no compelling reason). Rotax has a whole range of engines (not aircraft engines) that are fitted with NGK or for which there are no explicit Rotax spark plugs. Correct is: "Rotax does not supply NGK plugs for its aircraft engines anymore". So it's the other way around. That is a fact. The why - which could also be interesting - remains in the dark because neither Rotax nor NGK give a position on this. NGK has always excluded aircraft engines from its spark plugs - see the label on the package. Thus NGK has never been in the responsibility and would continue to be - that always went well so far. The problem was probably only staged by Rotax or affects only Rotax - maybe Rotax only meant well but made it bad for the consumer.

I heard a completely different story: during the development of the 914 series, spark plugs were sought that had a higher heat resistance (not heat rating) and were also certified for aircrafts. I don't know why Rotax didn't do the project with NGK. There were probably Rotax internal reasons - the simple wisdom of a purchaser.

The Rotax spark plug is not a high tech spark plug, basically like NGK only with 2 ground electrodes - nothing else. Probably no platinum etc. Ground electrodes interfere with flame spread, so 2 electrodes are worse than one or better would be even none and the principle of sliding spark makes it worse.

The high price is not justified by anything, It was indeed the lifetime with 200h on paper extended but in reality this also achieves the NGK. Also the low quantities do not justify a sevenfold price. Spark plugs are produced fully automatically, the Rotax spark plug is absolute standard and the imprinting of the Rotax logo costs practically nothing. I think already from 1000 pieces a new printing stencil (tampon) is inserted and the packaging costs also hardly more.

The Rotax spark plug replaces the plugs for the 582 (new cylinder head), 912 UL, 912 ULS, 914 and 915 (2-stroke, 4-stroke, suction and injected). Rotax does not disclose any technical data except the electrode gap. The earlier NGK spark plugs were different for each type - different heat value different electrode gap.

How should a single spark plug replace the various NGK's (there are also other spark plug brands suitable for Rotax)? This is only possible because the spark is in principle managed by each spark plug. But the different spark plugs were matched to the different engines. For one engine type or another, the Rotax spark plug can only be a compromise - it can't cover all types optimally - otherwise the many different spark plug types would be invalid anyway and the spark plug manufacturers would have been leading us around by the nose all this time. I do not believe that the Rotax spark plug is a "wonder plug" and represents the optimum for all Rotax aircraft engines.

Let's not wait years to determine what effect the new plug has on our new or old engine. Just change it - you can screw it out again and report your experience.

I had a terrifying experience with the new sparkplugs. The guts blew right out of the end of the plug. Almost a disaster! 

Thanks for your response,

at a german forum a Rotax owner reported that the german service told a customer by phone that the reliability of the "new" spark plugs are poor. This Information is years ago. Can you tell us: is this your experience of the past or in present times? If it happened with spark plugs from 2020 and 2021 then that is an ongoing unsolved time bomb.I am interested in facts. Informations are welcome but better are real experiences like yours.