Saturday, June 3, 2017

Spark Plug Heat Ranges

When the space for the ceramic looks much deeper, there is actually more total insulation against the heat going out of the back of the spark plug and into the engine compartment. This determines the heat of the plug, not whether it's made out of iridium, platinum, copper, or even nickel like on my old 89 Yamaha XT600 Spark Plug. (Related video) 

In the case of my 2004 Nissan Frontier, I noticed that one of the old spark plugs was a colder temperature index of 5 instead of 9. On NGK's it's very easy to tell the temperature ranges as a 1 is coldest, a 9 is the hottest, like what is supposed to be in my Nissan Frontier, but this was a 5, which was probably making for a little spark knock as the spark plug wasn't staying hot enough, unlike it's 5 other friends who were doing more of the work. The slight miss of this engine for the last several years? Mystery solved!

Side note: I hate anti-seize. As it ages, it becomes anti-remove, or whatever you want to say about how it makes it hard to remove a spark plug!

What are some reasons you'd change your heat ranges? A lot of people assume hotter means more performance, but as you can see for my Nissan Frontier, they've already chosen the hottest plug. The truth is, you're not going to be able to do better than what the manufacturer decided you needed for the heat range of your engine unless you've done significant modifications, which may change the needs of your engine.

Most commonly, people go colder on the heat range of their spark plug because of forced induction, be it a super charger or turbo charger, with great over all engine temperatures, having a lower heat range on the spark plug can be a preventative against knock or more minor power losing per-ignition.

I've seen people do okay with a hotter plug a lot of times when they always short tripped their vehicle or for some reason the engine was staying too cold, but honestly, they're usually lying to themselves. I bought a more expensive plug, it's hotter? No, if you check how the manufacturer rates the heat ranges, you'll find it's pretty difficult to buy plugs that are even in the wrong heat range unless you do a special order, knowing how the numbers for that spark plug manufacturer and how they tell you what heat range it is.

Let's get back to why I say people are lying to themselves. You see, just because it's an iridium and it gets a better spark, it doesn't mean you've actually changed the heat range of your spark plug! That's spark. The heat range is the temperature of the spark plug when it's NOT igniting the fuel/air mixture.

If a visual and practical example, help you learn, be sure to check out my video about this below: