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Spark Plugs for Newbies
- Thread starter DaleFredriks
- Start date
![[dunno]](/images/smilies/icon_smile_dunno.gif "Dunno [dunno]"){kind=icon}
![[driving]](/images/smilies/icon_smile_driving.gif "Driving [driving]"){kind=icon}
I find that parts houses and resellers like Mountune speak from both sides of their mouths on spark plugs, they recommend the Iridium or Ruthenium plugs and sell them based on the fact the the two metals are used because the metal reduces displacement of the electrodes so the plugs last 100K or more miles without having a detectable change in gap. Then make typical marketing bull shit statements like "we change ours at 10K miles to "insure" top performance" a total BS statement that sells lots of expensive plug designed for long life. Same with user claims that the metal makes a "hotter", "stronger", or more "powerful" spark. The number of people in the public and this forum that make silly statements of increased power or quicker starting or refer to a "butt" dyno are adrift in the placebo zone. If changing your plugs made your car faster that is all you would hear from NGK advertising but they can't because it is not true! All these metals do is reduce electrode "wear" and make the gap distance last longer to reduce maintenance costs for the manufacturer (100K service interval) and end user to insure the car from the factory will run clean for 50K miles. Why pay for long life plugs and replace them at 10% of their life, just keep them and send the money to me and I'll have a Sioux Princess ask the four winds to make your car faster. Guaranteed to work as well as changing your plugs and proven to require much less work on a stock FiST or MP215 modded one!
BTW, the Ruthenium plugs have reached the point the electrode gap will not change appreciably for 150-200K miles, almost a "lifetime" plug for the average car. That does not stop the insulator from being contaminated from oil or ash build up but the proper heat range can control that somewhat. As to higher performance plug requirements I'll leave that discussion to the the people that are into that. I am totally satisfied with the MP215 power level for my needs.
BTW, the Ruthenium plugs have reached the point the electrode gap will not change appreciably for 150-200K miles, almost a "lifetime" plug for the average car. That does not stop the insulator from being contaminated from oil or ash build up but the proper heat range can control that somewhat. As to higher performance plug requirements I'll leave that discussion to the the people that are into that. I am totally satisfied with the MP215 power level for my needs.
![[nono]](/images/smilies/icon_smile_nono.gif "No No [nono]"){kind=icon}
When switching to E85 running a hotter plug is advised at times as it helps with cold starting (As noted above). This is more advised with n/A motors however, but it depends on the engine, design, N/A vs. Boost etc. Otherwise E85 has a cooler burn compared/higher knock to regular pump gasoline and the timing/boost can be adjusted accordingly. It depends on your goals for your car. For a race motor things swing different along the pendulum than a full street car.
I disagree here is a great post that explains it.
The dude who posted this engineers ignition systems.
"I'm going to have to jump in here real quick and comment on heat range and cold starting. Heat range has EVERYTHING to do with cold starts. Look at it this way...if we weren't worried about cold starts and fouling, we'd just put stone cold plugs in everything for maximum protection against preignition and call it good.
Hotter plugs have longer ceramic tips; think of tip length as the length of the path to the heatsink (cylinder head). Cold plugs have short tips to dissipate the heat quickly. It's that physical length that's so important because it represents what we call the "shunt path". In other words, the resistance along the insulator tip determines whether it's easier to conduct ignition current across the gap or along the insulator to ground. A new or plug at operating temperature has a shunt resistance that's basically infinite. When an engine is starting, and the mixture is enriched, and fuel and soot are distributed on the insulator. These deposits are conductive, dropping the resistance of the insulator surface and potentially allowing current flow to ground - up inside the spark plug. Once the insulator is shunted, the current flows along the insulator to ground, and there's no spark in the gap (so most likely no start).
Spark gap is critical to cold starting as well. Colder plugs must use smaller gaps, hotter plugs can use larger gaps since their shunt path is longer. That's why worn plugs start misfiring, the gap resistance becomes higher than the shunt resistance, so the current doesn't always flow through the gap. Using a wider gap on a colder plug will have you misfiring quickly during a cold start, or not starting at all. Conversely, wider gaps on hotter plugs (to a point) make for easier starting because the fuel won't foul the gap as easily, and it's statistically more likely to get a combustible mixture in between a larger electrode gap...but you've got to have the tip length to support the gap. There's a lot more to it, but that's the nickel version. It also has to do with voltage drops along the circuit, with higher energy deliveries being at the points of greatest voltage drop. Consider the drops along the way at the spark plug suppression resistor, terminations, etc.
There is no operating of an engine requiring more "demand voltage" than cold starting. This is because the voltage required to stimulate electron flow across the gap is higher when the metals are coldest. This pretty much limits spark gap since if we go too far and there isn't enough voltage available to break down, or ionize, the gap we probably don't start. Cold starting can use all the ignition voltage you have available, especially when you consider that battery voltage is lower, and dropped further by the current draw of the cranking motor, etc. And there's quenching...energy drawn from the gap byy the relatively cold surroundings. Kind of like lighting a cold fireplace compared to re-lighting one that's already hot but out of wood...it lights much easier warm (takes less ENERGY). There's a lot more to it, and I can answer questions if needed. 20+ years engineering ignition systems and spark plugs."
https://r.tapatalk.com/shareLink/to...&share_fid=14159&share_type=t&link_source=app
Sent from my LG-LS997 using Tapatalk
The dude who posted this engineers ignition systems.
"I'm going to have to jump in here real quick and comment on heat range and cold starting. Heat range has EVERYTHING to do with cold starts. Look at it this way...if we weren't worried about cold starts and fouling, we'd just put stone cold plugs in everything for maximum protection against preignition and call it good.
Hotter plugs have longer ceramic tips; think of tip length as the length of the path to the heatsink (cylinder head). Cold plugs have short tips to dissipate the heat quickly. It's that physical length that's so important because it represents what we call the "shunt path". In other words, the resistance along the insulator tip determines whether it's easier to conduct ignition current across the gap or along the insulator to ground. A new or plug at operating temperature has a shunt resistance that's basically infinite. When an engine is starting, and the mixture is enriched, and fuel and soot are distributed on the insulator. These deposits are conductive, dropping the resistance of the insulator surface and potentially allowing current flow to ground - up inside the spark plug. Once the insulator is shunted, the current flows along the insulator to ground, and there's no spark in the gap (so most likely no start).
Spark gap is critical to cold starting as well. Colder plugs must use smaller gaps, hotter plugs can use larger gaps since their shunt path is longer. That's why worn plugs start misfiring, the gap resistance becomes higher than the shunt resistance, so the current doesn't always flow through the gap. Using a wider gap on a colder plug will have you misfiring quickly during a cold start, or not starting at all. Conversely, wider gaps on hotter plugs (to a point) make for easier starting because the fuel won't foul the gap as easily, and it's statistically more likely to get a combustible mixture in between a larger electrode gap...but you've got to have the tip length to support the gap. There's a lot more to it, but that's the nickel version. It also has to do with voltage drops along the circuit, with higher energy deliveries being at the points of greatest voltage drop. Consider the drops along the way at the spark plug suppression resistor, terminations, etc.
There is no operating of an engine requiring more "demand voltage" than cold starting. This is because the voltage required to stimulate electron flow across the gap is higher when the metals are coldest. This pretty much limits spark gap since if we go too far and there isn't enough voltage available to break down, or ionize, the gap we probably don't start. Cold starting can use all the ignition voltage you have available, especially when you consider that battery voltage is lower, and dropped further by the current draw of the cranking motor, etc. And there's quenching...energy drawn from the gap byy the relatively cold surroundings. Kind of like lighting a cold fireplace compared to re-lighting one that's already hot but out of wood...it lights much easier warm (takes less ENERGY). There's a lot more to it, and I can answer questions if needed. 20+ years engineering ignition systems and spark plugs."
https://r.tapatalk.com/shareLink/to...&share_fid=14159&share_type=t&link_source=app
Sent from my LG-LS997 using Tapatalk
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