So we all know that when we run a tune (I'm recently upgraded from COBB Stage 1 to Dizzy Stage1 93), we're concerned about temps and spark to prevent knocking. The whole "step colder" spark plugs become very important with the timing advancement and increased temperatures (because you know very well that the increased torque/power makes us throttle happy, and throttle happy needs more boost and higher rpm, and boost and rpm increases temp dramatically in the little FiST). Jason over at Dizzy has a really nice chart describing the steps and stages of tuning in his tech articles that recommends NGK LTR7IX-11 plugs. If you go to NGK's site, or any car parts store, you'll find that the plug that "fits" the Fiesta ST is the LTR6IX, but the LTR7IX is the "one step colder". (NOTE: Stores and plug manufacturers will not list the step colder plugs for the Fiesta, just because it's not the OEM heat rating. I verified this with NGK and the step colder plugs will "fit"!)
In search of the best plug possible, I went to NGK's (Sorry Denso guys, I only researched NGK out of personal preference) extremely informational website and learned a few things:
Temperatures - the Heat Rating of a plug basically describes the plugs designed ability to dissipate the heat away from the electrode. If the electrode can cool more efficiently, then it won't stay red hot - too hot increases the risk for pre-ignition and knocking ("DANGER Will Robinson"). The difference in the plug part numbers (LTR"6"IX vs LTR"7"IX) is that heat rating; the higher the number goes, the better the heat dissipation. Essentially, the "step colder" plug (the higher number "7" in the part number) can perform at temps of up to 200oF higher than the "6". If you go too cold, you risk carbon deposits, but I think fixing carbon deposits on the plug (change the plugs) is a lot cheaper than what pre-ignition can cause. NGK Heat rating of 7 is what the Dr. ordered.
Metallurgy - Nickel, platinum, iridium, ruthenium, etc. What'll be the next coolest name, Kryptonium? All this is more than gimmick, it's improvement in technology and material chemistry. Apparently the Ruthenium is the latest and greatest at NGK (still primarily platinum and copper); more reliable, more efficient, better conductivity, more resistant to oxidation, etc. NGK even has a trademark (I'm guessing a patent as well) on their latest Ruthenium HX series. They are claiming an improvement over the Iridium (which was an improvement over platinum, which was an improvement over nickel, which was an improvement over.......ad nauseum).
Ground Electrode design - Here's where it gets interesting. The ground electrode (the "J" shaped arm that reaches over the center electrode, by whatever gap you set) design has also benefitted from advanced research and technology. I remember an old friend of mine that used to build 400+HP Chevy 350's for clients with old drag strip Nova's and such, he once told me that it helps to face the spark plug gap towards the intake valve as close as you can for better combustion. Whether he was off his rocker or not is open to debate, but the guys in the lab are testing and trying to improve this (normal, split, tapered, pronged, etc.). All that to say, the NGK LTR7IX plugs have tapered ground electrode design. NGK also has a ILZTR6A8G, the OEM replacement, and the ILZTR7A8G which is the same plug but the "step colder"; with a conventional flat tip ground electrode. Finally (you guessed it?), NGK offers two ground electrode designs for the new Ruthenium HX plugs (LTR*BHX); one is a thin prong that points directly towards the center electrode (DFE, Double Fine Electrode), and the other is a small flat tip that protrudes out over the central electrode (PSPE, Projected Square Platinum Electrode). The DFE is a patented design specifically for use with non-turbo applications, and the PSPE is specifically for turbo and supercharged applications. In fact, NGK only recommends the ILZTR*A8G (Laser Iridium) and LTR*BHX (Ruthenium HX) for turbo applications. The LTR*IX (Iridium IX) is for specifically listed for "naturally aspirated" engines.
Here's something else! The gap recommended as you tune your fiesta is to drop the stock 0.032" gap down to 0.028". NGK recommends against dropping a gap anymore than 0.005" inches from the gap setting from NGK. I bring this up because the LTR7IX-11 comes from NGK with a 0.044" gap - NGK suggests that dropping the 0.044" down to 0.028" is too radical a bend and the ground electrode can be weakened.
For all these reasons above, I'm leaning towards the NGK Ruthenium HX LTR7BHX (w/ PSPE electrode). It's the latest & greatest technology, it's electrodes are designed specifically for turbo, it comes with a 0.032" which can be "safely" closed to 0.028", and the "7" model is the "step colder" operating temp. My local ADVANCED Auto Parts has them in stock for $14.99/plug.
What are you using and why? Please feel free to add or even correct anything here - I'm just asking!
In search of the best plug possible, I went to NGK's (Sorry Denso guys, I only researched NGK out of personal preference) extremely informational website and learned a few things:
Temperatures - the Heat Rating of a plug basically describes the plugs designed ability to dissipate the heat away from the electrode. If the electrode can cool more efficiently, then it won't stay red hot - too hot increases the risk for pre-ignition and knocking ("DANGER Will Robinson"). The difference in the plug part numbers (LTR"6"IX vs LTR"7"IX) is that heat rating; the higher the number goes, the better the heat dissipation. Essentially, the "step colder" plug (the higher number "7" in the part number) can perform at temps of up to 200oF higher than the "6". If you go too cold, you risk carbon deposits, but I think fixing carbon deposits on the plug (change the plugs) is a lot cheaper than what pre-ignition can cause. NGK Heat rating of 7 is what the Dr. ordered.
Metallurgy - Nickel, platinum, iridium, ruthenium, etc. What'll be the next coolest name, Kryptonium? All this is more than gimmick, it's improvement in technology and material chemistry. Apparently the Ruthenium is the latest and greatest at NGK (still primarily platinum and copper); more reliable, more efficient, better conductivity, more resistant to oxidation, etc. NGK even has a trademark (I'm guessing a patent as well) on their latest Ruthenium HX series. They are claiming an improvement over the Iridium (which was an improvement over platinum, which was an improvement over nickel, which was an improvement over.......ad nauseum).
Ground Electrode design - Here's where it gets interesting. The ground electrode (the "J" shaped arm that reaches over the center electrode, by whatever gap you set) design has also benefitted from advanced research and technology. I remember an old friend of mine that used to build 400+HP Chevy 350's for clients with old drag strip Nova's and such, he once told me that it helps to face the spark plug gap towards the intake valve as close as you can for better combustion. Whether he was off his rocker or not is open to debate, but the guys in the lab are testing and trying to improve this (normal, split, tapered, pronged, etc.). All that to say, the NGK LTR7IX plugs have tapered ground electrode design. NGK also has a ILZTR6A8G, the OEM replacement, and the ILZTR7A8G which is the same plug but the "step colder"; with a conventional flat tip ground electrode. Finally (you guessed it?), NGK offers two ground electrode designs for the new Ruthenium HX plugs (LTR*BHX); one is a thin prong that points directly towards the center electrode (DFE, Double Fine Electrode), and the other is a small flat tip that protrudes out over the central electrode (PSPE, Projected Square Platinum Electrode). The DFE is a patented design specifically for use with non-turbo applications, and the PSPE is specifically for turbo and supercharged applications. In fact, NGK only recommends the ILZTR*A8G (Laser Iridium) and LTR*BHX (Ruthenium HX) for turbo applications. The LTR*IX (Iridium IX) is for specifically listed for "naturally aspirated" engines.
Here's something else! The gap recommended as you tune your fiesta is to drop the stock 0.032" gap down to 0.028". NGK recommends against dropping a gap anymore than 0.005" inches from the gap setting from NGK. I bring this up because the LTR7IX-11 comes from NGK with a 0.044" gap - NGK suggests that dropping the 0.044" down to 0.028" is too radical a bend and the ground electrode can be weakened.
For all these reasons above, I'm leaning towards the NGK Ruthenium HX LTR7BHX (w/ PSPE electrode). It's the latest & greatest technology, it's electrodes are designed specifically for turbo, it comes with a 0.032" which can be "safely" closed to 0.028", and the "7" model is the "step colder" operating temp. My local ADVANCED Auto Parts has them in stock for $14.99/plug.
What are you using and why? Please feel free to add or even correct anything here - I'm just asking!
