Spark plug change interval

Discussion in 'General Discussion' started by Paul G, Jan 13, 2020.

Car Parts
  1. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    . 040" works great with Iridiums with oem coils/wires.
     
    AMS3 likes this.
  2. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    . 040 also works great with aftermarket coils and wires.
     
    AMS3 likes this.
  3. Kiwi SRT10

    Kiwi SRT10 Active Member Supporting Member

    Messages:
    120
    Likes Received:
    67
    Joined:
    Dec 16, 2019
    Location:
    New Zealand
    woah woah Easy tiger. I got Felpro intakes gaskets off Rockauto and also Spark plugs at the same time. I didn't bother with fancy million mile plugs as I will never do that many miles. I would need a million dollar fuel budget first lol:D
    I know what you mean about coils. Considering heat is their enemy I would rather see them in a different cooler place too. I can't have everything my way....apparently. Does look tidy tho. I wonder how many coils fail due to heat??
     
    AMS3 likes this.
  4. Kiwi SRT10

    Kiwi SRT10 Active Member Supporting Member

    Messages:
    120
    Likes Received:
    67
    Joined:
    Dec 16, 2019
    Location:
    New Zealand
    Thanks Ronnie
    You are a wealth of information for us newbies
     
    AMS3 likes this.
  5. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    Excerpts from: https://www.autoserviceprofessional...on-coils-What-every-tech-needs-to-know?Page=7

    Even though the coil may be capable of an output of 40,000 volts, this almost never happens in real life. What will happen is that the voltage will rise as high as it takes in order for the spark plug gap to ionize. Based on the variables discussed earlier, the voltage required could be as low as 3,000 volts or as high as 30,000 volts.

    The lower voltage can be enough to ionize the gap under high speed, light load conditions. The maximum required voltage happens under heavy acceleration where the load is high and the fuel mixture is rich.

    Typical ignition firing voltages are between 8 kv and 22 kv. Having a higher voltage available from the coil may not be an advantage.

    The engine computer will know in advance when it wants a spark from the coil. The target is to start the dwell period enough in advance of spark event for the primary coil current to reach full energy storage. This time depends somewhat on battery voltage and more on the exact internal temperature of the ignition coil. This may be harder to predict. For this reason, most coil electronics include a coil current limiting feature. When the target current level is reached, the coil driver transistor is turned partially off, limiting any further rise in the current. The goal is to keep the coil current limit time as short as possible to avoid excess heating in the coil driver.

    When the connection to the spark plug opens or the plug becomes un-fireable, the voltage from the coil will rise. Oftentimes this will create a breakdown in the insulation of the spark plug boot or wires. This results in an arc that passes through the side of the boot and nails the nearest point at ground potential. Once an arc has occurred, the pinhole created by the arc represents permanent damage to that boot.

    When it gets bad enough, the arc will occur first even though the spark plug has been restored to normal firing condition. The solution is to replace the damaged boot and damaged spark plug. END


    So...Coil relocation may not be a good idea; not if Internal Coil Temperature is calculated into the ECU, and it sounds like it is.
    As mentioned earlier, plugs will require only enough voltage from the coil to fire. Eg: 70,000 volt coils DO NOT fire at 70,000 volts every time they discharge.
     
    TrailMix, Kiwi SRT10 and AMS3 like this.
  6. CaptnCrash

    CaptnCrash Full Access Member

    Messages:
    212
    Likes Received:
    31
    Joined:
    Jul 1, 2014
    Very good Ronnie. Also there's a slight wrench in the Viper motor ignition plan most people don't realize. The Gen III uses what they call a wasted spark system. Simply this is where a single coil handles 2 cylinders. The net of this is (1) it fires the plugs twice as much resulting in significantly more wear, and (2) it limits RPM potential because a coil can only fire so many times per second. Physics imposes this limit because of the time it takes the field to collapse and rebuild in the winding's. Coil construction can have some effect on this but not a whole lot. (3) they do get hotter internally. (4) you are firing 2 plugs at the same time instead of just one which requires good wires and plugs to be successful. You will change plugs more often. (5) this arrangement does help with emissions.

    Coil relocation probably not going to help here and MOPAR in the FSM is very specific about wire routing and the use of the proper retainers because this all has an effect on the energy transfer.

    Yes I know the GEN I / II Vipers had the coils mounted between the intake and firewall, but the requirements for routing and retainers was the same.

    Gen IV and beyond have coil near plug like a GM LS motor and normal firing. The wires are very short so less loss and with a coil per plug less chance of misfires.
     
    Kiwi SRT10 and AMS3 like this.
  7. AMS3

    AMS3 Active Member

    Messages:
    157
    Likes Received:
    29
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    Good question.
     
  8. AMS3

    AMS3 Active Member

    Messages:
    157
    Likes Received:
    29
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    So I was thinking of getting the Demon Coils and wires that Kiwi is looking at. My engine as of now is stock. I have the Venom under pulley that will be getting installed, and a larger throttle body, for now that is. Is Demon overkill for me, or will it be good?
     
  9. AMS3

    AMS3 Active Member

    Messages:
    157
    Likes Received:
    29
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    You guys are fantastic with your knowledge of these vehicles. Just sucks to have to remove the intake to access all of this.
     
  10. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    I wasn't aware the Gen III used a wasted-spark system. To have a plug fire on the exhaust-stroke in an attempt to reduce emissions apparently works.
     
  11. GSJake

    GSJake Member

    Messages:
    113
    Likes Received:
    14
    Joined:
    Feb 13, 2018
    Is there a pattern Ronnie?
    Thanks.
     
  12. beastmode1

    beastmode1 Full Access Member

    Messages:
    274
    Likes Received:
    42
    Joined:
    Oct 2, 2014
    Location:
    Denver, CO
    THE WELSHM, I am looking to replace my spark plugs in the 10 what would you recommend? You used the Bosch Multi fire what part number and did you have to gap them? Please advise.
     
  13. beastmode1

    beastmode1 Full Access Member

    Messages:
    274
    Likes Received:
    42
    Joined:
    Oct 2, 2014
    Location:
    Denver, CO
    D
    Did you have to gap them and what gap specs?
     
  14. Kiwi SRT10

    Kiwi SRT10 Active Member Supporting Member

    Messages:
    120
    Likes Received:
    67
    Joined:
    Dec 16, 2019
    Location:
    New Zealand
    Here's a thought. Back in the early school days we were taught electricity is like water will flow the easiest route ie the path with the least resistance. What if you have 11.5:1 compression and foot hard up it, won't the spark all go out the exhaust cycled plug?? Cause it's easy?
    I don't pretend to know electronic systems, just thinking out loud
     
  15. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    My street engine is currently 11:1
    No issues with a 040 gap when racing and shifting at 6600.
    I haven't tried 050 and don't really see the need. The burn patterns on all 10 are awesome and I'm happy with that. There are NO fuel washed areas with the exception of right "under" the injector,which is normal. I zero decked the block and the heads have high-swirl Chambers making it easier to compress and light off the mixture.
    I DO try hard to have as much of the combustible mixture as possible burn INSIDE the engine! Better power and better mileage. If the 2nd spark wants to see what's behind the exhaust valve, that's fine !
     
  16. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    Yes, there is but if you want to be a Rebel and not follow it, you are fine using: "From the center, out to each end".
    Do it in a couple of stages, say 100 then 200 inch pounds.
    Don't bother removing the fuel rails, just leave then bolted up.
    Access the bolts from the top "holes" (a 1/4" drive ratchet and extension works great).
    #9 can be a character-building exercise. If you use a piece of electrical tape to attach your bolt to your socket when reinstalling it, that helps. Or some heavy grease, or tiny robots also help.
    Take your time.
    The wiper bezel makes a nice place to rest your forehead while kneeling on the bumper.
     
    GSJake likes this.
  17. AMS3

    AMS3 Active Member

    Messages:
    157
    Likes Received:
    29
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    #9 can be a character-building exercise. If you use a piece of electrical tape to attach your bolt to your socket when reinstalling it, that helps. Or some heavy grease, or tiny robots also help.
    Take your time.
    The wiper bezel makes a nice place to rest your forehead while kneeling on the bumper."

    Now that's some funny stuff, LOL! I'm an ex Navy guy, and we have colorful language. I wish we were advanced enough in this world to be able to download the knowledge from one brain to another, you are a wealth of knowledge, just like the others on here.
     
  18. VIPR PWR

    VIPR PWR Full Access Member

    Messages:
    4,899
    Likes Received:
    127
    Joined:
    Jun 12, 2007
    Location:
    FL
    I changed my plugs out the first time at approximately 12000 miles.. after changing them I noticed I was getting worse mileage about 2mpg worse ... truck idled and ran fine .. couldn’t figure what happened ... so I just drove it for another 50000 miles before I finally noticed a slight mis fire at light throttle cruising .. not at idle and not under wot ... drove it from SC all the way back to Tampa FL area ... decided to check codes .. yeap had 2 misfire codes ... started pulling plugs and found one plug bent post ... see pics .. had me worried that something happened in that cyl. To bend it ... then my 1 brain cell realized that hey you’ve had piss poor mileage since you replaced them years ago ..
    I had to have bent it when installing the plugs back then ... replaced the plugs and mileage was back up ,, felt a little more power .. no problems at all ....
    I don’t recommend waiting 50000 miles between plug changes .. but I didn’t have any problems except the mileage from the first change .. check out the pics and see what you think about the wear on them , color of them .. and the bent post on the one that still operated fine for a very long time ...
     

    Attached Files:

  19. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    [QUOTE="Now that's some funny stuff, LOL! I'm an ex Navy guy, and we have colorful language. I wish we were advanced enough in this world to be able to download the knowledge from one brain to another, you are a wealth of knowledge, just like the others on here.[/QUOTE]

    I've always remembered a quote from a Holley Engineer, years ago, and it stuck with me:

    "When your theory and results disagree, believe the results and invent a new theory".
     
    VIPR PWR and AMS3 like this.
  20. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    2,939
    Likes Received:
    231
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta


    That black plug wasn't really doing it's part to contribute.
    The rest look normal (as far as I can tell from the photos)
    What happened to the other (3) plugs? I hope they didn't look like the black one. ;)