Ngk Dp9ae

[scottdom]

I've been running the stock plugs for ten years now, but have been reading and researching the NGK DP9AE plug because they claim it is a cooler plug that will reduce the head temp by 5-10 degrees. Does anyone have any experience with this plug?

[honda400ex2003]

dpr9z is the cooler one for the 400 i believe. that one may work also but i would suggest running the dpr9z instead. the stock one is dpr8z. steve

[scottdom]

was there a big difference between the z and the ae? did you ever use it and could you tell a difference with the temps? thanks for your input.

[honda400ex2003]

I havent used the cooler plugs before and i am not sure if there is a difference between ae and z. sorry bro. lol. I would just get a dpr9z and use that to cool it down. I have heard that they make quite a difference though, mostly it is used out in the desert or to make it so an engine does not ping so easy. otherwise i would not really see a major difference in them. with the correct jetting i would say that you should not have any overheating issues anyway without temps being 100+. The cooler plug may also require a bit of a jetting change since you will not be burning as much of the fuel with the spark since there is less of it to burn it all. i am not completely sure on this though, just a thought. I am not actually sure how they achieve a cooler running plug but i would assume it puts out less spark thus making it cooler. steve

[honda400ex2003]

5-10 degrees is not that much to worry about unless you are right on the edge of like 250+ for an oil temp all the time. Just riding a bit different by shifting sooner could lower the temps more than 5-10 degrees. steve

[F-16Guy]

A cooler plug does not mean cooler engine temps, it means cooler PLUG temps. A spark plug has to reach and maintain a certain temperature to be hot enough to prevent carbon build-up, yet not get so hot as to melt the electrode. With modified engines, the average combustion temps can increase, so the plug must be able to shed that extra heat to stay in the proper heat range. A plug's heat range designation has to do with it's ability to shed or retain heat to stay in the optimum heat range, not weather or not it makes your engine run hotter or cooler. If your jetting is correct and you're melting electrodes, go to a cooler plug. If your jetting is correct but you're carbon fouling plugs, go to a hotter plug.

[honda400ex2003]

thanks for the info f-16! i read a bit about the temps of the plugs from another one of your threads about it last night. good info, steve