Do fancy spark plugs really make that much difference ?
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  1. #1
    Tadpole
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    Default Do fancy spark plugs really make that much difference ?

    Please forgive my ignorance on what may be a trivial issue for some folks, but,
    I read with interest on some of the fuel consumption threads that changing spark plugs to either Beru UltraX or Bosch Super4 gave 8-10% better fuel consumption. This sounds like a lot. Does this mean that if I use normal plugs then 10% of my fuel is going out the exhaust unburned ? or is there some other principle involved here ?

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    James.

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    I've put Bosch 4's in one R19 and Iridium in the other. Don't think it makes any difference to the fuel consumption.
    Used 7.7l/100km on a 1800km trip on or just below the speed limit and 7.93/100km on a 600km trip (half on the speed limit and half above - 120 to 140)

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    1000+ Posts alan moore's Avatar
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    I run Bosch Super 4s in the 306, don't know if they make any difference, but I do get 38 MPG (7.5 L/100k ) on day to day driving to work. Half of the trip is on the freeway.

    Years ago while playing with a single cam 2L BMW on Webers and much modified, a 4Hp gain at the wheels difference was achieved with Splitfire plugs over new standard NGKs. Maybe the difference in this case had more to do with the large chamber, poor plug placement, 11.5 comp ratio, Avgas, and needing 25 degrees initial advance to get the flame front to work over the really ugly lump on the pistons.

    In four valve motors like my 2L 306 the plug is placed in the centre of a much better shaped chamber.

    But maybe if I had used the some of these new Super4s or Beru plugs in the BM, I might have got the same advantage. Saying that, multiple earth electrode plugs have been around for decades, I just did not test them in the BMW.
    '56 Renault 750 (16TS Power)
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    Just guessing (as I've never experienced a difference, merely because I never check consumption) I'd say that better burn characteristics - assuming this is the case - mean that you need less fuel to give X amount of power - therefore for a given speed, you'll have a lesser throttle opening. As I say, just a guess.

    Stuey


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  5. #5
    Tadpole
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    Found the NGK website a little bit more informative out of the spark plug manufactureres. I followed the link to the IRIDIUM IX.
    They say fuel efficiency is related to ignitability performance.
    So with their 0.6mm electrode you can have a lean limit 17.6 parts air to one part fuel (as opposed to 15.1 for normal plugs) . They seem to be implying the lean limit is proportional to electrode diameter. If this is a key factor then the DENSO iridium with a 0.4mm electrode should be better again.

    So will my ECU lean out the mixture to 17.6 to take advantage of this ?

    Conversely I found these audi guys saying copper is the way to go with turbo cars because of heat dissipation issues
    http://forums.audiworld.com/a4/msgs/1541554.phtml

    James.

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    1000+ Posts Fordman's Avatar
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    Default NGK Iridium IX

    I also found the NGK website to be informative - they have a table which shows approximate life expectancy for various types.
    The smaller diameter produces spark at lower voltage but needs a harder electrode (eg iridium is harder than platinum) or it wears out too soon.
    Reading between the lines, a 0.8 dia platinum plug is good for 100,000 kms and the 0.6 dia Iridium is good for 50-60,000 kms but has a better spark. If they made a 0.8 dia Iridium it would last about 150,000 kms by their logic. Denso have the 0.4 Iridium which seems to be for racing motor cycles mainly but would have lower life than NGK?

    My recent experience is that the NGK Iridium plugs work as they claim. I developed a slight miss under load (up hills with a fairly well laden EF Falcon) while driving across the Nullarbor in September, with NGK standard plugs which had done about 20,000 kms and should have still been OK. After I got back to Perth it got worse over a couple of weeks on metro roads. I wanted to get platinum plugs to match the original OEM but instead got the "new" Iridium IX NGK's, even though I suspected it was not the plugs, but they were due for change anyway. Immediately, the miss was gone, the engine pulled well and I thought it was miraculously cured. However, after about a month the miss gradually started again. Then I found one of the plug leads hidden under the manifold was arcing externally (I could hear it and see it in the dark). Replaced that lead and now runs well. What the Iridium plugs were doing was producing a good spark at the lower available voltage and in effect covering up the problem with the lead until it got worse.

    If they last for 50,000 kms I would be happy.

    Cheers.

  7. #7
    BiX
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    I have found a good set of plugs make a huge difference. I used to change plugs my car every 5000km. I was finding with the carbies tuned how i liked them, that they would foul around town or sat at idle for a few minutes. I went to the NGK iridium and haven't had a problem since. I have also found that i need only cahnge them about every 20k which means cost wise they are on par with the Bosch ones i used to run.

    Indexing plugs can make a difference of a few hp (one make series like formula Vee etc do this), and also going to twin plugs in a 2valve motor can add 10 to 15% more power and makes it more drivable(this is used on alot of aero engines and also alot of motorbikes)

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    i use the beru plugs in my 205 gti and i wouldnt change em for the world[well maybe for the world].i noticed better starting ,idle and engine power.they combust better by giving better spark so they burn all the fuel not just %85 as in most plugs[thats what they mean about better milage as ypou use all the fuel].they are multi probe so gapping is not an issue and you are supposed to get very good mileage.i have not done a mileage check with these plugs.
    i had a major service about 3 mnths ago[cam belt ,water pump,all filters ect]the mechanic put ngk plugs in.the car went ok but was missing a certain something from before.
    i changed dizzy cap and leads about 3 weeks ago and deciced to put in new beru plugs.
    when i put them in [before the leads and cap change]i noticed it straight away and my car had that little but noticable difference back.now they are not cheap[$8.50 rrp]but are supposed to last a long time.
    i used to use golden lodge plugs in my old 504's and found them to be the best plug i ever used but i cant find them anymore and im not shure if they make em for the 205.
    if anyone knows where to get them[excluding the italian job]please tell me.
    so if you can spare the coin,give them ago,you wont be sorry.
    p.s.i have heard scare stories from another mechanic who swears by ngk[cause they stock em and make money via mark up]about beru plugs fouling in motors over 100.000km but i have not had any problems with mine and my motor has 176.000km nor have i heard bad reports from other users,only good reports.-BAZZ

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    1000+ Posts HONG KONG PUGGY's Avatar
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    Quote Originally Posted by JimB


    Conversely I found these audi guys saying copper is the way to go with turbo cars because of heat dissipation issues
    http://forums.audiworld.com/a4/msgs/1541554.phtml

    James.
    James,
    As well as a few French cars, I also have a Saab 9000 turbo. The recommended plug for them was NGK BCP7ES copper. Even these days if you get it professionally tuned, the plug you get NGK copper as first choice, (or a platinum plug if you ask for it,) and all the Saab forums still recommend these for turbo cars. One thing I did notice when choosing a replacement plug was that Bosch do not recommend use of their Super4 plug in turbos, where as they do list the 2 electrode platinum as one choice. I'd like to know why this is just for curiosity.
    The other thing is....resistor or non resistor?
    There are so many types and varients of plugs today it makes your head spin
    Chris

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    Quote Originally Posted by alan moore
    I run Bosch Super 4s in the 306, don't know if they make any difference, but I do get 38 MPG (7.5 L/100k ) on day to day driving to work. Half of the trip is on the freeway.

    Years ago while playing with a single cam 2L BMW on Webers and much modified, a 4Hp gain at the wheels difference was achieved with Splitfire plugs over new standard NGKs. Maybe the difference in this case had more to do with the large chamber, poor plug placement, 11.5 comp ratio, Avgas, and needing 25 degrees initial advance to get the flame front to work over the really ugly lump on the pistons.

    In four valve motors like my 2L 306 the plug is placed in the centre of a much better shaped chamber.

    But maybe if I had used the some of these new Super4s or Beru plugs in the BM, I might have got the same advantage. Saying that, multiple earth electrode plugs have been around for decades, I just did not test them in the BMW.
    Hi Alan,
    as you are getting this great fuel consumption with a 306 in town what is it on a long trip? The R19 gets 9 to 9.5 in town at best doing relatively short trips - it's an automatic
    Cheers

  11. #11
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    Hi,

    Hope it is OK to join the discussion.

    Splitfire plugs were mentioned without any discussion of them.

    I drive an R10 with a 1.4 motor.

    I have never found a plug that matches Splitfires.

    As a conservative observation using Splitfires, my 10 loves unleaded in preference to leaded, when it was available; begs to be valve-bounced; becomes so competitive that I have to drive with the handbrake half on; grunts going up hills at other cars, just for fun, not because of the required effort to go up the hill; begs to go everywhere in 2nd gear at full revs and always makes me go through round-a-bouts in an opposite lock slide at about 20kmh, with one rear wheel squeeling loudly.

    I know it is terrible to drive an R10 and have a friend who has a twin turbo Lexus Soarer (and also loves rice), but I convinced him to try Splitfires in it. This was after I took him around the block in the R10 at Mach 3. He still stutters and clenches his fists when he tells others of the experience. I have now convinced him that twin turbo Lexus Soarers are really quite conservative cars. He didn't believe that cars could the things that the 10 takes in its daily stride.

    The point being, that after the Splitfires were installed, he thinks he might be able to catch the 10 in a tour around the block.

    As you have guessed by now, I love my 10 and am sold on Splitfire plugs.

  12. #12
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    Quote Originally Posted by JimB
    So will my ECU lean out the mixture to 17.6 to take advantage of this ?
    Maybe if by 'lean limit' they're referring to the point at which knock occurs, but I doubt if they are, because the fuel/air ratio is only one variable in this.

    Otherwise, if the iridium plugs mean that more complete burn characteristics result in less oxygen in the waste gases for a given amount of fuel consumed, the O2 sensor may detect this and the ECU then compensates by leaning the mixture. Again, this is subject to other variables and inputs (like intake air temperature and knock sensor etc.).

    Stuey


    2003 PEUGEOT 206 GTi

  13. #13
    Tadpole
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    I was looking for a reason for this resistor /no-resistor plugs. I remembered
    the magnacor website had some info on this.
    "Always use resistor spark plugs if the vehicle manufacturer specifies them, as the resistance is there to not only to help reduce RFI, but also to extend the life of spark plugs by reducing tip erosion."
    They also go to great lengths to explain how their cables protect the ECU from EMI from the ignition cables. They claim the EMI is responsible for some rough engines.
    So for these people who tried fancy plugs and had problems maybe it is not the plugs which are dodgey but rather they tend to be more electrically noisy with certain cables and hence the running problems ?

    and so I stumbled on yet another spark plug type which magnacor gave a good wrap on. These magnacor guys are so negative it is amazing they had anything good to say about another company.
    http://www.torquemaster.it/main1uk.htm
    and
    http://www.extremespark.com/Frequent...0Questions.htm

    240000miles on these plugs ?
    Anyone familiar with these ?

    James.

  14. #14
    1000+ Posts CHRI'S16's Avatar
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    In my 306 I found very little difference when any given set of plugs is brand new. But as the plug ages and becomes more and more "worn", the good plugs start to come in to their own. As the cheaper plugs age their "power" or ignition capabilities are not as close to their peak, as say racing plugs. Which in the life span of both sets of plugs could really start to vary the fuel consumption.
    However;
    In race terms it is certainly true, for my Rotax 125cc, 13,000rpm 29Hp 2 stroke kart engine, i have a NGK RACING plug to start and warm the engine up. But its useless above 10,000rpm. It misses to often and can't hack the oil burn at those speeds. Were as my DENSO Iridium plugs once up to temp are solid all the way to redline all day everyday, and cope with racing loads much better.
    Having said that any spark plug (the Denso) that costs $35 should be pretty special. - Chris
    ... ptui!

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    Oh .... dear me!

  16. #16
    1000+ Posts alan moore's Avatar
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    JoBo,
    Unfortunately with an auto you are throwing away a few MPG. I don't know if 19s had lock up converters to improve things. 19s in general were quite economical.

    My 306 does not seem to get comparably as good fuel economy on a run as around town. Possibly as I am often pushing it along a bit. Around 6 to 6.3L/100 km. With a bike trailer and bike on the back, at 110 the economy drops off to 7.5L/100, because of the aerodynamic and rolling drag, no doubt.

    I am happy with the Super4s in the 306, but probably don't get the best value out of them, as I change them every 15 -20 000km, when they may well be still performing fine at 30 000.

    Unleaded fuel has given plugs much greater life. Who would have run plugs for 40 000 km in the seventies. I changed mine religiously, at that time, with the points and oil at 5000km. I still think plugs and oil are cheap. To make a standard plug (and profit) with the precision necessary for $4 ea amazes me.
    '56 Renault 750 (16TS Power)
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  17. #17
    Tadpole
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    Hi Alan ,

    Your fuel consumption is amazing. My pug is doing 13l/100km in city driving and this is not getting stuck in traffic and I am not driving hard.
    It is a 2001 auto Cabrio. The engines runs quietly, there is no sputtering or backfires. I thought it was trapped in "limp home" mode but then reviewed
    the manual which shows
    13.8 city and 6.6 hwy
    I compare this to the numbers I got from
    http://www.greenhouse.gov.au/fuelguide/pubs/2002-03.pdf
    10.0 city 6.4 hwy

    So who do I believe ?

  18. #18
    1000+ Posts alan moore's Avatar
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    I get around 750 km for around 50L driving from the outer southern suburbs to the northside of Brisbane and back, but as a shiftworker I miss the traffic whatever shift I am on.

    I use BP Visco 5000 full synthetic, and I do have a little gizmo or gimmick on my car that may improve it and I admit will be coming off when I sell. It is a set of magnets that clamp around the fuel line and is placed as close to the fuel rail as possible. I have done no exhaustive tests, but at the time I fitted it, I thought I gained about 50k extra per tankful when I put it on. The claim was ala Peter Brock that the fuel molecules are aligned. It only cost $5 new in a box at a swap meet. The blurb sucked me in about better fuel economy and power.

    Also mine seems to go possibly better than others. At a day at Willowbank some time ago when there were a few Froggies there, I found that Rich(Zen), in a quite new(possibly to its' detriment on Hp) 206 GTI 180 did not have more than two car lenghths on me down the straight, against my standard 100Kw 306 XT. My car I expect would have been 100Kg heavier, and I am guessing at 90Kg, I would be a good 35 heavier than Rich. My time on the Sprint track on tired old Contis was 1.07.4, which I was happy with in my bog standard car.

    But I am sure my magnets have not given me another 50 hp or 10mpg, or every manufacturer would have one, but my car does get good economy.
    '56 Renault 750 (16TS Power)
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  19. #19
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    Just ordered some new plugs for the RSC...

    Couldnt find Beru (as they looked the biz), & NGK dont do an Iridium yet!!!
    So its platinum @ just over $20 a pop

    Edit: had a look this morning & the normal plug tool used wont fit, as the plugs are SOOO deep in the engine... Is there a common tool for removing plugs from frenchies? (i.e. some form of slimline thingy)

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    Quote Originally Posted by nate
    Just ordered some new plugs for the RSC...

    Couldnt find Beru (as they looked the biz), & NGK dont do an Iridium yet!!!
    So its platinum @ just over $20 a pop
    Aren't the plugs in an RSC already platinum? They do have a 100,000k change interval. So unless your motor has already covered a lot of k's they may not need changing.

  21. #21
    1000+ Posts PeterT's Avatar
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    Beru Ultra X are approx. $10 each from Auto France.

    '92 205 Mi16
    '90 Mi16x4

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    Hi Alan,
    your answers are interesting. Thanks.
    the 19 has a lock up converter and i did have the a/c on most of the time.

  23. #23
    Tadpole
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    multi electrode plugs are good for 1 thing, thats throwing them into the sea. They are for 1 thing and 1 thing only extended service intervals, extended service intervals sell cars as people today don't want to have their cars serviced as its a pain they want to be able to do 60k miles without servicing etc. They do not give you more power etc, also they shroud the spark.

    Precious metal tips are not worth the money, they never last as long as they claim and they also suffer from fouling especially in high output engines. They are fitted to most new cars and new pugs/citroens and renaults but if you check them they need replaced way before they are supposed to.

    NGK's are the best plug I have found, used them for years. Single electrode copper core. Decent life, good service, reliable, good price.

  24. #24
    1000+ Posts dino's Avatar
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    multi electrode plugs are good for 1 thing, thats throwing them into the sea. They are for 1 thing and 1 thing only extended service intervals, extended service intervals sell cars as people today don't want to have their cars serviced as its a pain they want to be able to do 60k miles without servicing etc. They do not give you more power etc, also they shroud the spark.

    Precious metal tips are not worth the money, they never last as long as they claim and they also suffer from fouling especially in high output engines. They are fitted to most new cars and new pugs/citroens and renaults but if you check them they need replaced way before they are supposed to.

    NGK's are the best plug I have found, used them for years. Single electrode copper core. Decent life, good service, reliable, good price.



    man knows what he s talking about.....

    If you ve ever used multi elctrode plugs (ie bosch 4s) on anything thats running even a touch rich or lets say has worn valvestem seals...forget it...the electrodes will literally start to touch....they are a pile of junk.....throwing them in the sea is 2 good for them.....
    NGKs are great....replace them as required and thats all thats needed....sharp electrode edges are whats important......comparing apples with apples (as mentioned by chris for specific uses) is what its about....I had a guy come in today...his "hot" vk v8 gained an extra kw when the dyno guy put in a set of platinums......when I asked him wether it ever occured to him to account for the fact that the dyno figure was comparing "old" plugs versus "new"....he didn t have much to say......most plug test show platinums as UNDERPERFORMERS....but if you need to remove a manifold on a v6 camry and you are paying $100 an hour to change plugs...yes the platinums may be a wiser option for the average "clueless" camry driver......

    cheers



    dino


    ps. Leigh you are right...splitfires are good....hot fours did a plug comparison a few years ago....they performed well.....I remeber them mentioning the directhits as well....I think its important to consider the state of tune and many other variables that affect plug performance especially considering the fact that we are talking about quite a varied range of vehicles.....
    Last edited by dino; 18th December 2004 at 08:25 PM.

  25. #25
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    Quote Originally Posted by Simon
    Aren't the plugs in an RSC already platinum? They do have a 100,000k change interval. So unless your motor has already covered a lot of k's they may not need changing.
    yep thats rite... but it apparently fixes the cold start problem...
    i do the oil every 5k (well about 4k) & doing manual next...

    i'm just trying to keep it in the absolute best condition...
    it cant hurt!

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