tom111

Hi,

I would like to buy a new iridium plugs for my 26cc Zenoah & my 29cc CY, NGK sells the below 2 models:

NGK CR8HIX Iridium Spark Plug
NGK CR7HIX Iridium Spark Plug

Which one should I get??? I know that the difference is that the CR8HIX is a colder plug, which means that it will cool off faster than the CR7HIX, which is not always a good thing in case the plug will drop below to its normal working temperature which is ~450 Celsius.

Thanks.

SAVAGEJIM

I dont know about the "8," but if the "7" iridium is of similar temp range of the cmr7h, then I personally say go for the "7."

splcrazy

i think the 8 is shorter than the 7 , im using iridium in my baja's 5b's and ive also used stock normal plugs and i cant tell the differance in performance except that irdium costs more

Mudgy

Numbers for this manufacturer have nothing to do with the reach, thread type, or if it is a taper fit/washer type. Most makes, the number dictates the heat range.
Heat range is acheived by length of the insulation cone over the electrode... read more here...
http://www.ngksparkplugs.com/techinf...000&country=US
edit:

I suppose if spark plugs are rated like glow plugs...then a cold plug is better for leaner / high octane conditions, whereas a hotter plug may be good for oily mix/low octane/rich settings?

BTW, NGK (IMO) are the best to use...Champion is junk, and Bosch can't handle hi RPM. AC delco is also rubbish, Nippon Denso...not too bad as second fiddle to NGK.

Gotta think of it this way:
the humble spark plug would be the most highly stressed engine component:

One end copping compression and combustion properties
The other end getting a shot of lightning shoved through it every cycle...now that's a component dealing with a lot!!

cyclops1970

My Feedback: (5)

plus the iridium has a more precise ingition pattern , sparks in same spots which will burn more effiently

tom111

The “8” model is just a colder one, reduction in “1 number”: for example between the “8” series to the “7” series will result in increase of 70-100 Celsius degrees in the temperature that the plug works, the plug needs ~450 degrees so as Mudgy mentioned if you run your engine richer the temperature is lower therefore you will need a hotter plug, if you run it leaner than the temp of the engine is hotter than you will need a colder plug… the “warm” & “cold” refers to the ability of the plug to transfer heat from the combustion chamber, a colder plug will do it better & will cold faster…

The Iridium just offer better acceleration, high fuel efficiency and long engine life, at least that’s what they say… and it is only few $$$ more, but the basics with the series numbers & working temperature are valid also with these plugs…

rckiwi

I think you will find with NGK the higher the number the cooler it is, Champion are the other way, lower number colder!

tom111

Yes, with NGK - Higher number = Colder plug, with chanpion I am not sure, but if that's the case so its confusing [sm=confused.gif]

srt10

My Feedback: (20)

What about these plugs, anyone tried them?

http://www.e3sparkplugs.com/index.htm

tom111

These plugs looks good! But I am not sure which of their model will fit to the CY \ Zenoah engines & how much do they cost?

Mudgy

read carefully! they claim some models have a longer reach to improve the detonation characteristics, if this invades your squish zone too much, you'll pop a hole thru the top of yer pot!!
In the '70's Alfa Romeo used double electrode (earth side) plugs, aircraft have used quad electrode (earth side) to guarantee a spark for decades.
They are correct about the "sharp edge"
A spark will travel to a sharp(90deg) edge to conduct the line of electrons. A worn or (cleaned) plug will perform poorly. Hence the earth electrode design they have. A spark will fly to only 1 sharp edge at a time, so having 3 earth electrodes either means 3 times the plug life, or 300% chance of a fat spark igniting every time. Jeez, for the hours clocked up on a RC motor, these would only be an alternative if the price was right. If it was chalk & cheese (between costs) I wouldn't bother. I am in no way connected to NGK, either, but the ol' tried'n'tested will win in my books any day.
However, if you are racing for sheep stations (instead of 2 dollar tin cups!) and need that 1/100th of a second from your lap times, well....knock yerself out.
The reason I mentioned Bosch being crook (I was a Bosch agent for 10 yrs)
We once tuned a RX 3 Mazda, put Bosch plugs in, and it ran like a dog.... Put NGK's in, and all was fixed. As you know , Mr Robert Bosch invented the spark plug, but that doesn't mean they are the best. I have found the NGK's work very well for Hi rpm applications, so 2 stroke seems to be an NGK dominated area. Hey, if these e3's are the next new thing, well, we need to give them a go...who knows? could be the next leader in this field?


time will tell

srt10

My Feedback: (20)

Looks like an E3.12 will fit our motors.. and around 6bucks

Cacique_2002

I was told to use the colder plug whenever the air temp is below 70 deg F, it the air is warmer than that then use the hotter plug. Remember that the engine runs on a air-fuel mixture, so I guess the air temp had a lot to do with it.

srt10

My Feedback: (20)

Using a cold plug in cold weather could cause the plug to foul sooner

Cacique_2002

sorry maybe I got it backwards, use the hotter plug in cold weather and use the colder plug in hot weather.

srt10

My Feedback: (20)

This explains alot..
http://dirtbike.off-road.com/dirtbik....jsp?id=332655

tom111

Thanks, this is a great guide, it surely explains it all... I will need a hotter plug than what I have now, I just get to the fouling zone to often.

srt10

My Feedback: (20)

Yah, its good stuff..

txtkiller

The oil ratio has a lot to do with that. The stock plugs are just fine. A fouled plug can be fixed easy.[8D]

srt10

My Feedback: (20)

25:1 will not foul a plug.
Carb setting could be the cause.

tom111

I run my cars with 1:25 & I like to run it as rich as possible, just before the engine chokes out of gas… this might be the cause since it lowers the temperature, from the other hand I have this problem only with my new 29CC engine, I never had this issue with my 26CC Zenoah (with the same settings)

By the way – how can I fix so easily a fouled plug? I emailed NGK & they answered that I need a sand blaster in order to clean the fouled plugs…

Mudgy

don't sand blast 'em, you'll round off that "sharp edge"
If it can't be solvent cleaned, replace it...they are pretty cheap, after all.

SAVAGEJIM

I dont know, the NGK Iridium plugs go fro no less than $10 USD. At least I have not seen any cheaper than $10 USD.

tom111

Yes, 10$ is the minimum for the Iridium ones...

txtkiller

Yes it will. The carb settings don't foul a plug. I was told straight from a NGK rep. it would.[8D] Too much oil can cause a plug to foul out. I switched to 32:1 problem solved.They also told me how to clean the plug out properly.