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Denso spark plugs

T

Tweetr

Member
I need to replace the Denso spark plugs in my RV-4 with LSE Plasma II ignition. My local AutoZone doesn't have the Denso W24EMR-C or W27EMR-C plugs in stock. They also were unable to cross-reference these plugs with those of other manufacturers. Does anyone have cross-referenced part numbers for these plugs? NGK, Bosch, or whatever?

Thanks,
Tom Stearman
RV-4 with 1150 hours
(completed June 2000, still unpainted!)
 
just do a google search. I think they are really motorcycle plugs, and the lightspeed site has them for sale as well, you just need to buy 8 minimum.
 
Yeah, I know I can order them. I need equivalent part numbers so that I can buy them locally. My airplane is down and me need da spark plugs!
 
I don't know if you are willing to run plugs other than the Denso's, but the Auto Zone should have NGK 5422's or BR8ES. They are cheap and work very much good. I have been using these with my Lightspeed for around 250 hours now.

Best,
 
Bryan already touched on it, but I want to expand a bit...

Denso W24EMR-C = NGK BR8ES
Denso W27EMR-C = NGK BR9ES

Different heat ranges.

Klaus sells the Denso plugs relatively inexpensively, but I switched to NGKs and never looked back.

Link to a cheap source for the NGKs ($1.70/ea):
http://www.rvproject.com/pricewatch.html

I've seen them on Amazon shops before for less $ in larger quantities.

If you happen to be ordering from Aircraft Spruce, they even sell them (for slightly more $):
http://www.aircraftspruce.com/catalog/eppages/ngkplugs.php
 
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Thanks!

That's what I needed, thanks! My local O'Reilly's carries the NGK BR8ES and BR9ES.

Incidentally, Klaus Savier said he has less luck with the NGKs than the Densos. He thinks the Densos are better plugs. I'll pick up a set of NGKs, then order a set of Densos to keep on hand. He recommends changing plugs every couple of hundred hours. We're putting much more energy through them than automotive electronic ignitions do.
 
Tweetr said:
Incidentally, Klaus Savier said he has less luck with the NGKs than the Densos. He thinks the Densos are better plugs. I'll pick up a set of NGKs, then order a set of Densos to keep on hand. He recommends changing plugs every couple of hundred hours. We're putting much more energy through them than automotive electronic ignitions do.
Click to expand...

How does 1100+ trouble-free hours on NGKs sound in terms of "luck"? :)

Haven't had any issues whatsoever with the el cheapo NGK plugs. But I still do change the plugs every 150-200 hours. For less than $7, I can rationalize doing that. I do see measurable electrode wear.
 
Denso/NGK spark plugs

I have 1400+ hours on my RV8 now (IO-390-X) engine, fuel injected, Lightspeed Plasma 3 ignition. I have tried just about every brand of sparkplug in this engine and have always returned to the Denso sparkplugs from Klaus @ lightspeed ign. Since I do a lot of Air Racing with my RV8, I am always looking for the best performance that I can get. In order to rate my experience with sparkplugs on a number basis of 1 to 10 with 10 the best, I rate the Denso 27ESR-U the best @ 10. and the various NGK models @ 8 or 9.
I usually clean and regap them @.027 every 50 to 75 hrs. When the electrode begins to show excess wear usually after 150 hrs. I replace them. (they are cheap compared to Champion aircraft plugs) After comparing prices at local auto and speed shops, I find that Klaus's prices are very competitive, and his service is excellent.
Dick Martin
RV8 N233M
the fast one
 
Dick,

I'm surprised you use such a small spark plug gap (you mentioned .027").

I use .034" and regap if they're over .036". I figure I'm getting more spark energy out of the bigger gap, but that's just an assumption.

Curious why you use a smaller gap?
 
Dan,

My engine came with a Lightspeed Plasma II in place of the right mag. Denso W27EMR-C plugs were installed, so I'll swith to the NGK BR9ES. I know the heat range is different than the BR8ES plugs. How do you decide which plug to use?

Mike
 
dan said:
How does 1100+ trouble-free hours on NGKs sound in terms of "luck"? :)

Haven't had any issues whatsoever with the el cheapo NGK plugs. But I still do change the plugs every 150-200 hours. For less than $7, I can rationalize doing that. I do see measurable electrode wear.
Click to expand...
Standard issue on the Rotax 912S. The low price makes a big difference when you have to replace them every 50 hours...
 
alcladrv said:
Dan,

My engine came with a Lightspeed Plasma II in place of the right mag. Denso W27EMR-C plugs were installed, so I'll swith to the NGK BR9ES. I know the heat range is different than the BR8ES plugs. How do you decide which plug to use?

Mike
Click to expand...
My Lightspeed Plasma II came with W24EMR-C plugs originally, so that's why I went with the NGK BR8ES instead of the BR9ES.

I'm sure some spark plug expert out there will tell us about the critical difference in heat range between W24 and W27... :rolleyes:
 
Spark Plug Source

Believe it or not....
http://www.sparkplugs.com
has everything you need. I went all over town looking for replacements for my LS II Denso plugs with no luck but found them in two minutes at this website. Klaus and others really believe in the Denso plugs. :cool:
 
Dan,

I can comment on the gap for the Denso of NGK plugs. At 185 hours one of the coils of my LightSpeed Plasma II died. I talked to Klaus and he ask when I had last re-gapped them. I had not re-gapped the plugs in 185 hours and gaps were pretty wide due to erosion. Klaus said that wide gaps stress the coils, which will work as hard a needed to make the spark. He recommended regapping plugs at least every 100 hours and recommended a gap of .026 to .030, especially with high compression pistons (I have 9.2 to 1).

Dan Miller
RV-8 N3TU. 185 hours since July
 
I just replaced the worn Densos for NGK BR9ES. Gapped them to .032". Couldn't find a gap reference in the LSE installation manual, or maybe just missed it. No Densos available at the local motorcycle speed shop. Engine ran up fine, but haven't flown it yet. I would not expect any difference in performance. Longevity might be at the heart of the matter here. In a side by side comparison, the Denso just looks a bit nicer, more refined machining or something. Hard to nail it down. I might order the Densos from sparkplugs.com and change them out at next oil change and keep the NGK's as spares. Or, not. ;)
 
Brian Denk said:
I just replaced the worn Densos for NGK BR9ES. Gapped them to .032". Couldn't find a gap reference in the LSE installation manual, or maybe just missed it.
Click to expand...

It's in the manual. Here's a quote from: http://www.lightspeedengineering.com/Manuals/CdiManual_PlasmaII_II+_III.htm
2.8 SPARK PLUGS

Engines normally timed at 25 degrees BTDC:
These are normally engines with compression ratios less than 8.7:1. Gap spark plugs fired by the CDI to .032"-.040".

Engines normally timed at 20 degrees BTDC:
These are usually engines with compression ratios of 8.7:1 or higher. Gap spark plugs fired by the CDI to .026"-.035".

Turbo / Supercharged engines should gap the spark plugs to .026? - .035? while turbo normalized engines should gap the spark plugs according to the compression ratio.

Install the spark plugs and inserts using 15 and 25 lb/ft respectively, using anti-seize.
Click to expand...


And here's a quote from another "Spark Plugs" document on the LSE web site: http://www.lightspeedengineering.com/Products/Sparkplugs.htm
Gap spark plugs fired by Light Speed Engineering's PLASMA CDI systems to .032"-.045" for standard compression engines (7 - 8.5:1) and .026"-.034" for high compression engines (8.7 - 10:1). Turbo and Supercharged engines should run a spark plug gap of .026" - .034". Install the spark plugs and inserts using 15 and 25 lb/ft respectively, using anti-seize.
Click to expand...

FWIW, my 8.7:1 compression ratio is right on the line, so I picked a gap that straddled the line as well. .034" gap on my NGK plugs.
 
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