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Spark Plug Options

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325K views 620 replies 128 participants last post by  FWD_Fracas  
#1 · (Edited)
So, with the big turbos coming out, spark plug upgrades will be following very closely. When increasing the power by that much it is important to move to a slightly colder plug in order to keep cylinder temps down and reduce chances for pre-ignition/detonation.

The factory spark plug for the focus ST is an NGK plug PN: LTR6DI-8. If you break down the part number this is what you get.

LT (Long thread reach plug Tapered seat type 25mm) R (Resistor) 6 (heat range) D (Metal Shell Plating Spec Change) I (Laser Iridium) - 8 (0.8mm or .032")

The heat range for NGK plugs goes from 2 to 11 with 2 being the hottest and 11 being the coldest. This means that there are a couple options to go with for a colder spark plug.

The first is the NGK LTR7IX-11. This plug comes with a gap of 1.1mm or .044" and will require you to regap them to a range of .030" - .032". The IX at the end of the part number stands for High Performance Iridium.

The second option is the Denso ITV22.

I stands for iridium, and the letter T is the Thread Diameter x Hex size (14x16.0). The letter V represents the thread reach of 25mm with tapered seat. The heat range is designated by the number 22. This is equivalent to the NGK 7 and therefore one step colder than stock. The number 20 corresponds to the stock heat range or NGK 6.

We are going to be running the NGK LTR7IX-11's in our car with the GTX2867. We are not sure what gap we are going to run yet but will be experimenting with that a bit to see what works best.
 
#145 ·
I read somewhere that tuners consider safe -0.5 to -1.0 of timing being pulled. I might be wrong though. I will try one step colder too when the winter is over.
 
#144 ·
Just a lil addition, I've seen audis come with two different brand plugs in the same engine same cars while still new cars.
 
#151 ·
First a disclaimer that I'm no expert on the subject of spark plugs. With that said, colder plugs will likely have negligible to zero effect on exhaust/cat temps. If the plug itself gets too hot, it can cause detonation, which is basically a second explosion when the piston is traveling down and happens when previously unburned fuel in the cylinder is ignited by the hot plug. Of course, detonation is bad for your engine and should be avoided. If the plug gets super hot, you can run into pre-ignition which is far worse and can be fatal to your engine almost immediately. Pre-ignition happens during compression when the piston is traveling up and the fuel ignites from the super hot plug before it has a chance to spark. This pre-ignition tries to force the piston down but it is still on the upstroke. Colder plugs means just that. The plug is colder to help avoid detonation and pre-ignition, but does not affect exhaust or cat temperatures.
 
#148 ·
NGKs are what I run in everything else I own so Ill be looking at them if I feel the need to change em out!

Matt
 
#153 ·
#156 ·
I know ;)
 
#168 ·
Whiteblurrvt man you got to learn to read sarcasm. But enough of the turbo pics, this is a spark plug thread topic. So let's keep it on track!
 
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#170 ·
Just posted my logs in the datalog thread for BTB runs between stock and 1 step colder. Only problem is I don't know what I'm looking for or at..Lol

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#172 ·
I believe so. It's logged using LiveLink for SCT and Torrie's config file.

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