Am I ruining my engine?

Discussion in 'OT Driven' started by Doog, May 1, 2009.

  1. Doog

    Doog New Member

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    So im an auto parts store worker, probably a cliche one at that. I'll admit I'm not a guru by any means but I know enough to help out the average joe.

    So I decided to tune up my 86' 300zx turbo. I get a healthy discount so buying the most expensive plugs wasnt a problem. Best we offered happened to be iridium.

    Well, the day after I changed them I was talking with a customer and he was mentioning that a colder plug is best with a turbo engine.

    Well im getting a little pre-ignition, metal on metal sound. Dosnt sound nasty but it's not purring.

    Eh so im putting that info out there. Any input, recommendations, whatever.
     
  2. Boomdart

    Boomdart New Member

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    I don't know really...not without actually hearing it or knowing any previous history.

    However, did you make sure to gap your plugs correctly before you put them in? I couldn't imagine it's the piston hitting the spark plugs unless you really got the wrong spark plugs...plus I doubt they'd work for very long if that was happening.

    Is the 300zx your only car? IIRC they have oil-filled rocker arms/tappets, if they lose the oil in them they'll be a little noisy. You don't have to replace them, just soak them in oil while pressing/depressing the tappet to draw in the oil. This is not related to the spark plugs at all, but if it's just a little metal tapping noise it could be your problem.

    Someone correct me if I'm wrong here, don't want this guy taking off his rocker arms to do this if he doesn't have to. A lot of engines don't have what i'm talking about.
     
  3. Anudist

    Anudist Turnin' Jesus on, one lightswitch at a time.

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    Pre-ignition is never a good thing. Is it solely since you changed the plugs? A one step colder plug is a common change when tuning a turbo charged engine, but if you're car is mostly stock, using the factory recommended spark plug heat ratings is the best way to go. Iridiums really only last longer than standard plugs.

    Check to make sure your gaps are correctly set on the spark plugs as well.
     
  4. PanzerAce

    PanzerAce Active Member

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    Fail. Go get regular old non-coated, non-fancy shit plugs in the factory specified heat range, and make sure they have the proper gap.
     
  5. deusexaethera

    deusexaethera OT Supporter

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    ^^^ x2.

    Plain old copper sparks hottest and cools down fastest compared to any other metal used for sparkplug electrodes; it's only downfall is it wears out fast, not like that's really a big deal when they cost $2 apiece.

    Those hot-shit sparkplugs are a complete ripoff anymore; it's such a utilitarian piece of equipment, with virtually no room for improvement except to make it last longer, that there is no point even touching them unless they wear out -- assuming they even wear out on newer cars. Those iridium ones have a ridiculous lifetime.
     
  6. PanzerAce

    PanzerAce Active Member

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    I figure if 3 bucks a pop spark plugs are good enough for guys that actually race their cars, it's good enough for me.
     
  7. deusexaethera

    deusexaethera OT Supporter

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    Well, if the car comes with fancy sparkplugs, then there's no reason not to use them unless you modify the engine, because the engine designers will have taken into account the thermodynamic characteristics of the fancy sparkplugs. I think all new Nissans come with iridium-tipped plugs now, or at least all of their naturally-aspirated engines have them. And in that case, why not? It's one less thing to have to worry about; hell, you could probably weld them in place, given how durable iridium is.

    I remember probably 15 years ago a rep from my dad's company (nuclear defense contractor) did a demo at my middle school of various things they were working on, and one of them was a heat-storage device that was going to be used in satellites to ignite thruster fuel without any electronic ignition required. It consisted of a block of carbon encased in a 1/8" coating of pure iridium, and it would collect heat from sunlight focused on it by a lense or reflector of some sort. It would get hot enough to melt the carbon inside, and it would stay glowing yellow-hot for the entire time the satellite was behind the Earth on a 24-hour orbit. The iridium could care less about being that hot for that long; the predicted lifetime of the igniter was something like 50 years, far longer than the satellite would even be in orbit.
     
  8. amac88

    amac88 New Member

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    Ive talked to a master ASE tech about this, he recommended using the regular plugs the car comes with, no matter what. Even professional racers dont use the fancy iridium plugs. Use what the car comes with.
     
  9. PanzerAce

    PanzerAce Active Member

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    Because if a engine only lasts 3 hours, but the plugs last thousands of miles, wtf is the point? :mamoru:
     
  10. nindia

    nindia OT Supporter

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    i installed iridium tip plugs in my dads 4runner...didn't run the same...not bad...but not the same. next time around...i got regular "denso" or whatever oem brand plugs...gapped them properly...installed...ran like it used to (in a good way, before the iridium plugs)

    ever since then i've stuck to regular OEM spec plugs in anything i do plugs in
     
  11. 4W4K3

    4W4K3 New Member

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    Climbing on the bandwagon...

    I put fancy iridium plugs in my 86' MR2 and than washed my engine. Car failed to start afterward, I got the plugs wet and I wasn't getting any spark. I got a ride to the auto store and bought the cheap copper NGK's that Toyota recommends, put them in, and the car started right up.

    Thinking I had been duped I swapped the Iridiums BACK in after drying them all off. Car ran like complete shit. Took them out and threw them in the trash, put the coppers back in and went on my way.

    So, maybe I got defective plugs? OR maybe getting them wet ruined them?! Never seen that in my life, I wash my engine with copper plugs in all the time.
     
  12. PanzerAce

    PanzerAce Active Member

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    No, it's just that non copper plugs just suck balls.

    Which is probably why copper plugs are twice as much as Iridium or other fancy plugs at autozone :rofl:
     
  13. alltracman78

    alltracman78 New Member

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    Oh really?
    What makes coppers better than everything else?
     
  14. deusexaethera

    deusexaethera OT Supporter

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    Copper conducts both electricity and heat really well (better than pretty much everything except silver), so they spark hotter and cool off faster than any other kind of plugs. The only advantage of the platinum and iridium plugs is that they last longer.

    I believe the iridium plugs also need significantly higher voltage to spark properly, which makes them pretty much useless for older engines.
     
  15. pew pew pew

    pew pew pew OT Supporter

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    i always rocked NGK plain v-power in my GTI despite adding boost and stuff... just had to replace them more frequently but they were easy to change and like a buck fifty a piece. just hope he didnt give you plugs with a long electrode because umm.. that would explain your metal on metal noise :hsugh:
     
  16. Doog

    Doog New Member

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    Smashy Smashy. No pistons touching the elctrodes there, the noises ended up being the clutch on a defective a/c compressor.

    Finally got my wires in and the a/c is blowing cold, its actually running great. Though, on an off day ill probably toss some copper v powers back in there. I really would feel better following OE. Lesson learned, but at this point I dont see many draw backs. Engine runs well, gas mileage is slightly improved (remember I did a full tune up) throttle is jumpy and same with pick-up. Sounds were verifyed by a mechanic not to be detonation/pre-ignition, compressor just happened to go out at an inoppurtune time that caused some panic.



    Question though, it was mentioned that iridium plugs require more voltage to spark like a copper. Would tossing a preformance coil in there alleviate that problem? Or would it be straight fucking retarded? Common sense would point towards that being a terrible idea in terms of pre-ignition.I dont want to kill the fucking poor old ass bastard engine, just kinda gathering information of all the possibilties.


    And yes, I know there is a slight shade of picard.jpg to this thread...

    Everyone started somewhere you bastards, atleast im trying to learn :squint: I'd happily look like a jackass to get good info from people that know what they're talking about. Fuck it. :o
     
    Last edited: May 19, 2009
  17. alltracman78

    alltracman78 New Member

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    Copper does those.
    However did you ever bother to check the resistance of plug wires or coils?
    They're several THOUSAND ohms each. Not to mention the air gap the spark has to jump.
    The relatively small difference in the plug resistances doesn't really matter; the total resistance of the circuit [coil to plug wires to plug, across plug gap and back] isn't all that different from copper to iridium.
    The ignition circuit is designed to be high resistance, to create a higher voltage spark.

    Also, while copper conducts heat better, it's a MUCH thicker electrode that iridium [thinner metal holds less heat than thicker metal], which means it effectively holds LESS heat than the much thicker copper.

    And, because iridium is thinner it doesn't foul as easily as copper.
    And, because iridium has a sharper "edge" on the electrode the spark is more concentrated [it jumps to the edge of the center electrode, not the center of it] so it tends to be stronger.

    All this means that iridium plugs DON'T suck balls. Many more engines run fine with iridiums than don't.

    BTW, older engines didn't used to run coppers, the electrodes used to be made of nickel. Copper plugs didn't come out until the 60s or 70s.


    Professional racers tend to use the fancy iridium plugs over the copper ones.
    Here's a list of NGKs racing spark plugs. Not ONE is a copper alloy.
    http://www.ngksparkplugs.com/products/spark_plugs/racing.asp


    I wouldn't worry about a "stronger" coil right now, unless you're running non stock or are having bad misfire problems.
    But, to answer your question, a stronger spark won't cause preignition. It actually helps to alleviate it.

    If your engine is running fine with the iridiums [no surprise], I wouldn't bother getting new plugs. "If it ain't broke, don't fix it".
    But you can't go wrong with using the factory recommended plugs, as long as the engine is stock.

    Nothing wrong with that man, everyone has to start somewhere. :)
     

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