Quote from: explorergotoluvit on April 10, 2014, 12:28:09 AM
spark plugs should i replace them? starting to learn a lot about the ecoboost in this forum thanks to you all
Finally a topic I can chime in on; since I'm new to the whole forced induction thing too. But plugs is a universal performance-engine issue.
For those who stay stock, replacing the plugs to "upgrade" is not necessary until the maintenance schedule dictates it. However, in performance engines it's a must.
I see your an LMS guy, but I'm not sure which tune you're running. Might want to add that to your sig line.
If you're running a tune that requires you to use a higher octane fuel you should step down to a colder plug. But good news...there's a reason!
When fuel is refined further it becomes more concentrated and potent as it becomes more potent the octane rating goes up (just like booze) and with that also comes a raise in flash point, meaning it takes more heat to ignite the fuel. The reason you want a higher flash point is: as you increase the performance of your engine, by cramming more air and fuel into your cylinders, you're increasing the compression. As the gas mixture is compressed it gets hot, more compression means higher temps. If the plug itself is hot enough, this aids in raising the temp in the cylinder which is now acting as a glow plug, and the gas mixture detonates before the actual spark is delivered. This pre-detonation is known as spark-knock, and is a BAD THING.
What makes a plug actually hotter or colder? The amount of ceramic around the center electrode. The ceramic acts as a heat sink, so the more ceramic, the colder the plug, the less ceramic the hotter the plug and the more deposits it burns off.
As far as
upgrades go: Due to marketing, there are a lot of misnomers out there about what a plug upgrade gets you, and why. The application of high value metals used in plugs such as platinum, gold, silver, and noble metals such as iridium, magnesium, etc. were adopted for their high melting point and heat resistance, and has nothing to do with conductivity. Their ability to withstand high temps means they can make the center electrode much smaller and with sharper edges. By being smaller, they collect less deposits.
Firestone actually tried marketing polonium tipped plugs at one point under the questionable theory that the radioactivity would ionize the air within the gap, enhancing spark formation.
Yay capitalism!
Decreasing the gap is also important. I've a heard a good rule of thumb (for v8's anyway) is to decrease the gap 0.004" per 50hp added when increasing performance. Seems like most guys are running 0.030" in the 3.5L TT EB.
