Something interesting about spark plugs!
 

I just read something interesting about spark plug heat range selection.

It seems, for every 75-100HP you add to your motor, you should go one range/step colder when selecting spark plugs.

I never knew this to be honest! There you go, you learn something new every day ;)

Where did you read that? Not trying to doubt you, but curious. Do you have a link or the whole article. Sometimes, not all the time, things are taken out of context. If you can believe that.. :rolleyes:

It may not be that simple. I am not an expert just a 930 owner/addict.

I have 505 rwhp. So that is what ...about 594 at the motor? I was running cold (NGK 7 range) spark plugs and they kept getting fouled. I swapped them out for some hotter ones and it is better so far. Only more time (and miles) will tell.

I read it in a tech section on the NGK.com WEB site.

If you add significant HP gains to your motor with more boost, you will need a colder plug in order to remove heat from the combustion chamber more efficiently.

If you run a plug that is too hot for your motor, you risk detonation under heavy loads (which is BAD). If you run a colder plug for your motor, the only risk is that the plug will foul quicker.

I personally would rather be changing fouled plugs more frequently, than running the risk of severe engine damage by running a plug that is borderline :confused:

I'm currently running W3CS plugs and they seem to be performing better in my motor than the W4CS plugs I had in there previously.

What about the DPO's? Does the W3CS work better or just cheaper? will the W3CS work on a stock engine..and what did you pay for them?

Thanks

Bob

DPO's are Platinum plugs and have a longer lifespan than the CS's. The DPO's also fire more reliably on stock ignitions at higher than stock boost levels, but since I run a CDI, that's not really an issue for me. W3CS would work fine on a stock motor at stock boost levels. Certainly a cheaper alternative to the DPO's, at the same heat range as recommended by the factory.

I suspect the factory specified a 3 heat range because they knew their customers would be thrashing their cars on/off the track, so they wanted the extra insurance of running a colder plug.

At the end of the day, cost was the factor for me. I was quoted AUD$50 for each DPO plug :eek:, whereas I sourced the W3CS's for USD$2ea NEW :cool: So I purchased a dozen of them. Might pick up another 18 or so and just have them as spares, since I typically change my spark plugs every 5,000-7500km's.

EDIT: I know a warmer plug will stay cleaner longer, but I'm not risking pinging/detonation in my motor, especially at the boost levels I run. $50 on a set of plugs every 7,500k's is more cost effective than an engine rebuild :confused:

Merv, maybe you could get the W3DPO's sent to you from the USA at a reasonable cost.

Yeh, I looked into that, but it was still cost prohibitive, especially since I'll soon require 12 plugs :eek: The W3CS work very well and are significantly cheaper. My source is selling them at $2ea (excess stock), so I'm stocking up on those whilst I can :cool: