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Plugs for GT

1349 Views 66 Replies 7 Participants Last post by  2023BD
Here is some info I learned this morning. Believe it or not I did not have to go to Facebook to find it either. ;)

So the stock plugs on the Forte GT are 18849-08080 (NGK 97080 - SILZKR8E8G) heat range 8
NGK.com: SILZKR8E8G NGK 97080 Iridium Spark Plug - Best Car Spark Plug Replacement

The suggested replacement is NGK 1422 - 1LKR8E6 (heat range 8)
NGK.com: ILKR8E6 NGK 1422 Iridium Spark Plug - Best Car Spark Plug Replacement

Heat range 9 suggestion is NGK 97312 - 1LKR9Q7G (heat range 9)
NGK.com: ILKR9Q7G NGK 97312 Iridium Spark Plug - Best Car Spark Plug Replacement

Several people here are using the stock plugs stock gap (.031) with a Racechip with no issues on 87, 91 and 93 fuel
Several people are also using the heat range 9 and also have no issues.
Several people are using stock plugs or upgraded plugs with a closed up gap (.025-.028) and again no issues
I personally feel for under 250 hp the heat range 8 stock or NGK 1422 will do
If getting a more serious tune 250+ hp go with the NGK 97312 heat range 9

One person mentioned getting slight detonation with stock plugs and gap which might be remedied with a tighter gap.
Steve g - I keep my GTS on 7 always with stock plugs and premium fuel (California’s idea of premium) If it’s over 100 degrees outside I can get slight detonation under a really heavy load. Not worth re-gapping plugs over it.

Here is what I found interesting. The difference between the stock plug and the NGK 1422. The stock NGK plug uses a 1mm Iridium center electrode diameter and the NGK 1422 uses a .6mm Iridium center electrode diameter. The reason is that a smaller center electrode diameter requires less voltage to get a strong spark which also means you should not need to reduce gap compared to the stock plug. So the NGK 1422 should have a stronger spark than stock based on this theory. The second change is the stock NKG plug has an extended projection center electrode which puts the spark closer to center of combustion chamber. The NGK 1422 has a standard projection center electrode which pulls the spark slightly closer to the edge of combustion chamber. You can read all day about this projection stuff. One interesting thing is that less projection slightly retards timing and also works better if the combustion chamber temps are high. There are several other things as well but that was interesting.
NGK.com: NGK Center Electrode Designs

I decided to order a set of the NGK 1422 to try for the fun of it. I will let you know in a couple weeks if I notice any differences. Like I said right now I have no issues with my stock plugs and stock gap but maybe these NGK 1422 will make it feel even better. Worth a shot for $50. I have not decided on gap yet but might try them at the stock .031 since the larger gap tends to provide better fuel economy assuming the gap is not too big for the spark under full throttle loads with increased boost.
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Here is some info I learned this morning. Believe it or not I did not have to go to Facebook to find it either. ;)

So the stock plugs on the Forte GT are 18849-08080 (NGK 97080 - SILZKR8E8G) heat range 8
NGK.com: SILZKR8E8G NGK 97080 Iridium Spark Plug - Best Car Spark Plug Replacement

The suggested replacement is NGK 1422 - 1LKR8E6 (heat range 8)
NGK.com: SILZKR8E8G NGK 97080 Iridium Spark Plug - Best Car Spark Plug Replacement

Heat range 9 suggestion is NGK 97312 - 1LKR9Q7G (heat range 9)
NGK.com: ILKR9Q7G NGK 97312 Iridium Spark Plug - Best Car Spark Plug Replacement

Several people here are using the stock plugs stock gap (.31) with a Racechip with no issues on 87, 91 and 93 fuel
Several people are also using the heat range 9 and also have no issues.
Several people are using stock plugs or upgraded plugs with a closed up gap (.25-.28) and again no issues
I personally feel for under 250 hp the heat range 8 stock or NGK 1422 will do
If getting a more serious tune 250+ hp go with the NGK 97312 heat range 9

One person mentioned getting slight detonation with stock plugs and gap which might be remedied with a tighter gap.
Steve g - I keep my GTS on 7 always with stock plugs and premium fuel (California’s idea of premium) If it’s over 100 degrees outside I can get slight detonation under a really heavy load. Not worth re-gapping plugs over it.

Here is what I found interesting. The difference between the stock plug and the NGK 1422. The stock NGK plug uses a 1mm center electrode diameter and the NGK 1422 uses a .6mm center electrode diameter. The reason is that a smaller center electrode diameter requires less voltage to get a strong spark which should also means you should not need to reduce gap compared to the stock plug. So the NGK 1422 should have a stronger spark than stock based on this theory. The second change is the stock NKG plug has an extended projection center electrode which puts the spark closer to center of combustion chamber. The NGK 1422 has a standard projection center electrode which pulls the spark slightly closer to the edge of combustion chamber. You can read all day about this projection stuff. One interesting thing is that less projection slightly retards timing and also works better if the combustion chamber temps are high. There are several other things as well but that was interesting.
NGK.com: NGK Center Electrode Designs

I decided to order a set of the NGK 1422 to try for the fun of it. I will let you know in a couple weeks if I notice any differences. Like I said right now I have no issues with my stock plugs and stock gap but maybe these NGK 1422 will make it feel even better. Worth a shot for $50. I have not decided on gap yet but might try them at the stock .31 since the larger gap tends to provide better fuel economy assuming the gap is not too big for the spark under full throttle loads with increased boost.
Yes. I assume my issue is the extreme dry heat (100+) and California’s wonderful eco friendly flammable dogwater they call gasoline. I think a stronger ignition (MSD maybe) would benefit me far more than bending electrodes around to find some sweet spot. But again the issue is so far and few between I’m not putting in the effort to remedy unless I have coil failure or something...
Yes. I assume my issue is the extreme dry heat (100+) and California’s wonderful eco friendly flammable dogwater they call gasoline. I think a stronger ignition (MSD maybe) would benefit me far more than bending electrodes around to find some sweet spot. But again the issue is so far and few between I’m not putting in the effort to remedy unless I have coil failure or something...
Maybe that smaller diameter electrode coupled with less projection on the NGK 1422 would give you a stronger spark, better hot combustion chamber performance and slight retard that would overcome the high heat detonation you think your getting. You should be able to keep the stock gap and as well since the spark should be stronger. And the NGK 1422 is the stock heat range as well
Here is some info I learned this morning. Believe it or not I did not have to go to Facebook to find it either. ;)

So the stock plugs on the Forte GT are 18849-08080 (NGK 97080 - SILZKR8E8G) heat range 8
NGK.com: SILZKR8E8G NGK 97080 Iridium Spark Plug - Best Car Spark Plug Replacement

The suggested replacement is NGK 1422 - 1LKR8E6 (heat range 8)
NGK.com: SILZKR8E8G NGK 97080 Iridium Spark Plug - Best Car Spark Plug Replacement

Heat range 9 suggestion is NGK 97312 - 1LKR9Q7G (heat range 9)
NGK.com: ILKR9Q7G NGK 97312 Iridium Spark Plug - Best Car Spark Plug Replacement

Several people here are using the stock plugs stock gap (.31) with a Racechip with no issues on 87, 91 and 93 fuel
Several people are also using the heat range 9 and also have no issues.
Several people are using stock plugs or upgraded plugs with a closed up gap (.25-.28) and again no issues
I personally feel for under 250 hp the heat range 8 stock or NGK 1422 will do
If getting a more serious tune 250+ hp go with the NGK 97312 heat range 9

One person mentioned getting slight detonation with stock plugs and gap which might be remedied with a tighter gap.
Steve g - I keep my GTS on 7 always with stock plugs and premium fuel (California’s idea of premium) If it’s over 100 degrees outside I can get slight detonation under a really heavy load. Not worth re-gapping plugs over it.

Here is what I found interesting. The difference between the stock plug and the NGK 1422. The stock NGK plug uses a 1mm Iridium center electrode diameter and the NGK 1422 uses a .6mm Iridium center electrode diameter. The reason is that a smaller center electrode diameter requires less voltage to get a strong spark which also means you should not need to reduce gap compared to the stock plug. So the NGK 1422 should have a stronger spark than stock based on this theory. The second change is the stock NKG plug has an extended projection center electrode which puts the spark closer to center of combustion chamber. The NGK 1422 has a standard projection center electrode which pulls the spark slightly closer to the edge of combustion chamber. You can read all day about this projection stuff. One interesting thing is that less projection slightly retards timing and also works better if the combustion chamber temps are high. There are several other things as well but that was interesting.
NGK.com: NGK Center Electrode Designs

I decided to order a set of the NGK 1422 to try for the fun of it. I will let you know in a couple weeks if I notice any differences. Like I said right now I have no issues with my stock plugs and stock gap but maybe these NGK 1422 will make it feel even better. Worth a shot for $50. I have not decided on gap yet but might try them at the stock .31 since the larger gap tends to provide better fuel economy assuming the gap is not too big for the spark under full throttle loads with increased boost.
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So those vides are right on. IF you experience an issue try a reduced gap, otherwise stick with the stock .028-.031
One of the videos said the same thing I experienced, rough running when lean if gap is too small which is why I went back to .031

One thing you want to remember is that you want to run the largest gap you can that does not create any issues. A larger gap will be the most efficient and create the most complete burn. That is a simplified explanation but you get the idea I am sure. If increased boost starts to create a problem then try to reduce the gap to .028 and then again to .025 but that is only if there is a problem to begin with.

At the power we are running with basic pump gas tunes and piggybacks the heat range 8 seems to be just right. But you can use heat range 9 if you choose and still experience no issues as well.
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So those vides are right on. IF you experience an issue try a reduced gap, otherwise stick with the stock .28-.31
One of the videos said the same thing I experienced, rough running when lean if gap is too small which is why I went back to .31
At the power we are running with basic pump gas tunes and piggybacks the heat range 8 seems to be just right. But you can use heat range 9 if you choose and still experience no issues as well.
Since alot of RaceChips owners (I was one of them) are not able or choose not to data log thier runs to see how the boost ramps, the boost curve and hold at throughoutb the run, and other data that can be collected. It's hard get more knowledge data that can go with this topic of Spark Plugs and gap. At the time of owning the RaceChip GTS I wasn't thinking of data logging. My experience running Map 7 full time in FL weather on 93 octane with just a AFE closed box intake and stock plugs. Was fine for a while till I started getting misfire symptoms. I even unplugged the RaceChip and scheduled appointment with my dealership
(i have the kia documentation of the vist). They couldn't replicate it. Plugged the RaceChip and under map 7 boost load wierd stuff again. Got to a point at idle i got hiccups. Thats when I was done using RaceChip and pulled my stock plugs and they looked bad. I move on to JB4 and new HKS M45xl plugs. I did stock gap and on map2 or 3 noticed roughly the same from RaceChip. That's when gapped them under recommendations and my issues disappeared. I have bought and tested 4 sets of HKS M45xl plugs for testing purposes when I was gaining more knowledge. Stock gap, .026, .024,.022. .026 was a bit better. .024 no issues, .022 no issues. I'm currently on .022 because that was the last set I put in and left in. Now on ECU tune. Still running 93 and E85 mixing like I was on JB4. Now I'm also running water methanol injection same set at .022. Holding 24 boost throughout pulls. If anyone here with a RaceChip GTS and can data log run that would be great data to go over. This is my experience story 🙂
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I can data log with the obd fusion app but it only gives info in 1 second increments. Not as detailed as I wanted to be able to see. :(
At the time of owning the RaceChip GTS I wasn't thinking of data logging. My experience running Map 7 full time in FL weather on 93 octane with just a AFE closed box intake and stock plugs. Was fine for a while till I started getting misfire symptoms. I even unplugged the RaceChip and scheduled appointment with my dealership
How long ago did you have the Racechip? I am wondering if your issues were happening at higher rpm (5000-6500). It is possible that the lastest tune that the Racechip runs is set for less boost at the top end to prevent that from happening now. I honestly think my car is just as strong in 5 as it is in 7.
How long ago did you have the Racechip? I am wondering if your issues were happening at higher rpm (5000-6500). It is possible that the lastest tune that the Racechip runs is set for less boost at the top end to prevent that from happening now. I honestly think my car is just as strong in 5 as it is in 7.
I bought RaceChip when it was first batch launched. Under heavy load in that rpm range. I'm sure revisions have been done.
A lot of people miss this service manual warning:

Sleeve Font Rectangle Parallel Elbow
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A lot of people miss this service manual warning:

View attachment 92354
Yet its been done at professional level without issues with well made plugs in good condition or low mileage for many years.
A lot of people miss this service manual warning:

View attachment 92354
That’s what I learned over 25 years ago. Makes sense.
So I got the NGK 1422 plugs. I want to run a .028-.031 gap. Problem is the plug does not seem to be designed for this. The plug came with about a .02-.022 gap The tip needs to be opened up so much that the spark tip contact surface is no longer flat above the electrode, it is at an angle. I am trying to figure out if there is a better NGK Laser Iridium with the .6mm electrode that was designed for a .028-.031 gap.

I found some close alternatives, but a couple have special notes like extended shell or special gasket which I don't think I should try. The NGK 93819 might be what I am looking for I just need to look at the details a little closer.
NGK.com: ILKR8Q7 NGK 93819 Iridium Spark Plug - Best Car Spark Plug Replacement
So I got the NGK 1422 plugs. I want to run a .28-.31 gap. Problem is the plug does not seem to be designed for this. The plug came with about a .2-.22 gap The tip needs to be opened up so much that the spark tip contact surface is no longer flat above the electrode, it is at an angle. I am trying to figure out if there is a better NGK Laser Iridium with the .6mm electrode that was designed for a .28-.31 gap.

I found some close alternatives, but a couple have special notes like extended shell or special gasket which I don't think I should try. The NGK 93819 might be what I am looking for I just need to look at the details a little closer.
NGK 1422 was designed to come out the box at .024

Heat range 9, .028 gap, 0.6mm electrode. These are the plugs most will be running now vs the HKS M45xl plugs. I'll be running these on my next set with lowering the gap as well.
Look up HKS M40XL, heat range 8 like stock, 0.6 electrode. Gap not sure. Busy at the moment to look into full specs.
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