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How to avoid blown spark plugs in your tuned Stinger

Discussion in 'The Ultimate Kia Stinger Tuning Forum' started by Kia Stinger, Apr 3, 2018.

  1. Kia Stinger

    Kia Stinger United States Administrator Staff Member

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    Thanks to @KLR STINGER for this information:

    Any misfires from these piggybacks are 100% due to spark blow out on the transient increase in cylinder pressure during the onset of boost. The 3.3T pistons seem to have a high compression height with small quench area. This could be exacerbating the blow out issue. No matter what the piggyback maker says, you need to use the best quality plug you can with it gapped down to .022-4. This should resolve the misfire conditions that most seem to be having.
     
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  2. KLR STINGER

    KLR STINGER Canada Active Member

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    In addition you have to consider two things when exploring spark options for FI cars. Effective heat range and Gap.

    Heat range denotes how effective the plug is at pulling heat from the ground electrode and shell into the head. Every step colder in heat range, means about 70 degrees cooler electrode. The reason this is important in tuned FI cars, is that the large increases in combustion chamber pressure and heat from tuning (which is what is actually generating more torque and HP) causes the electrodes of the plugs to becoming glowing hot embers. At certain temps, this can lead to pre-ignition (also known as detonation), which can have terrible consequences for the piston ring lands where end gasses accumulate. Running a colder plug is cheap insurance because that 70 degrees colder can mean the difference a cracked ring land, or fused ring, thus saving you engine. General rule of thumb is for every 75-100 hp added, drop to the next colder range. the 3.3T run NGK 7 heat range, so running an NGK or equivalent 8 or 9 is good insurance.

    Gap has a direct correlation to spark blow out commonly experienced as misfires. Tuned cars running more than factory boost, need to be gapped down to ensure that the spark plug can do its only real job, which is to consistently fire ignition. Whatever heat range you choose to run, the plugs must be gapped between .022-26. Every car is different, some like alittle more or a little less, and unfortunately its trial and error, but .024 is probably a good starting point. Given the factor plugs have come out gapped at .036 I am not surprised at all at the amount of spark trouble people are having.

    Note that in some circumstances, too cold a plug and too tight a gap can have cold idle quality issues, but small price to pay to may consistent power production.

    There may also be several options when it comes to plugs. The physical specifications of the OEM plugs are as follows

    Hex Size: 16mm
    Thread Size 14mm
    Thread Reach : 26.5mm
    Seat type: Gasket

    With those spec you should be able to reverse engineer a number of fitment and heat ranges.
     
    Last edited: Apr 3, 2018
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  3. ihatecats78

    ihatecats78 United States Member

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    Forgive my ignorance, but does reducing the gap decrease horsepower if the vehicle is running stock boost? Can anyone explain why Kia has such a large gap initially?
     
  4. KLR STINGER

    KLR STINGER Canada Active Member

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    No, decreasing gap allows you to make MORE power, due to firing the combustion process more effectively and reliably. Too tight a gap can cause some idle quality issues, but in the range of .022-.026 won't cause any issues.
     
  5. ihatecats78

    ihatecats78 United States Member

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    Thanks for the reply.. So if what you're saying is true, then why would Kia call for a larger gap from the factory? Emissions?
     
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  6. TorkMe

    TorkMe United States Active Member Authorized Vendor

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  7. KLR STINGER

    KLR STINGER Canada Active Member

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    I mean, it's possible, but Torque limiting strategies in most pcms restrict torque demand/delivery through less intrusive means than causing misfires. Throttle control and spark retard are the common front line controls to manage, and these do not usually cause misfires. I would also expect that to happen in lower gears as a protection for driveline parts, not in higher gears under load.
     
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  8. TorkMe

    TorkMe United States Active Member Authorized Vendor

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  9. KLR STINGER

    KLR STINGER Canada Active Member

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    Interesting. I guess once tuning is online should be easy enough to determine and correct. Magic seems to have the SIM2K-260 cracked, so assuming the definitions are similar to other SIM2k variants, full tuning should be around the corner
     
    Last edited: Apr 4, 2018
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  10. Clearly Canadian

    Clearly Canadian Canada Stinger Enthusiast

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    I literally understood nothing in this entire thread, lol. I’ll take that as a sign to leave my car stock. :notworthy:
     
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  11. TorkMe

    TorkMe United States Active Member Authorized Vendor

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  12. GTB

    GTB United States Active Member

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    Just re-gapped the stock plugs to .28, Followed torks video. The car runs absolutely amazing now. tuned with JB4.
     
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  13. ihatecats78

    ihatecats78 United States Member

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    @KLR STINGER What aftermarket spark plugs do you recommend.. I noticed that HKS are about $25 a piece.. I've seen NKG for significantly less. Does the brand of spark plug make that big a difference?
     
  14. GTB

    GTB United States Active Member

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    Re-gap the stock plugs. Colder aftermarket plugs will foul out. read JB4 Review
     
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  15. StungBlueGT2

    StungBlueGT2 United States 1000 Posts Club! Sustaining Member

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    Thanks Sal for reposting this and great thread of information!

    One thing I haven’t seen mentioned is general cost to regap plugs if not inclined or able to change them personally? After reviewing the “install” videos I’m not sure I want to tackle that job. However I could find a experienced Kia mechanic to regap them and curious what the labor cost would be approximately. Would about an hour labor or $50-75 sound fair? Any suggestions are appreciated and thanks in advance all.:thumbup:
     
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  16. GTB

    GTB United States Active Member

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    I wouldn't be surprised if quoted 200 to 400 hundred dollars. it took me about 2 to 3 hours (Took my time) with the how-to video and I'm no stranger to the wrench. If you need a shop to do it, Find a very very very very reputable speed shop or mechanic perform this task. Best of luck :thumbup:
     
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  17. Kamauxx

    Kamauxx United States 2500 Posts Club!

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    Agreed. If I were to pay a shop to do it I would have to trust them a lot. It's too easy for the shop to just say "okay, we did it, give me money please" when in fact they didn't do a thing.

    @StungBlueGT2 do you have a friend who knows his way around a wrench that you trust? That may be a good in-between option.
     
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  18. Kamauxx

    Kamauxx United States 2500 Posts Club!

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    What size spark plug socket is needed to remove the stock plugs?

    5/8?
     
  19. GTB

    GTB United States Active Member

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    Yes sir
     
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  20. StungBlueGT2

    StungBlueGT2 United States 1000 Posts Club! Sustaining Member

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    Thanks for the feedback and that’s closer to what I was expecting.

    I was apprehensive when people said they completed the job in an hour, but thought a Kia tech or experienced shop might be able to replicate those times. I guessed 2+ for most and probably 3+ if I tried to tackle it...

    I'd prefer not use a shop, however I cannot work on vehicles in my neighborhood and don't have access to a local garage so a tuner shop may be my best option. I appreciate the tip and will heed the advice about "shady" shops. I would only take it somewhere I trust and would let me watch their work.:thumbup:
    Unfortunately I'm the most mechanically inclined of my friends, but will admit that my experience is with rebuilding old school carbureted engines like my Trans-Am. I'm confident I could handle the job, but I'd prefer only having someone familiar with Kia/Hyundai engines and specifically the 3.3T to touch my baby!;)
     
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