[scre103]

Couldn't find a thread on plugs, but could use some input. As we all know there are a lot of plug choices rangeing from $5.00 to $18.00 a plug for super duper platinum. One to four prongs /elctrodes? Of course the brand would be Bosh. Looking for a little extra pep and some increase in gas milage without heating the heads up too much. What do you guys like/ reccommend? There are a couple of choices in performance products, any thoughts. Thnx

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[banditsc]

I splurged the last time and went with the Bosh Platinum IR Fusion plugs #4506. I got them from RockAuto.com for $5.81 a piece with one of there 5% off coupons.

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[flash]

a quick search turned up quite a few threads about plugs - always use "more search options"

well, i recommend NGK iridium

platinum will add life expectancy at the expense of performance

iridium will add performance at the expense of life expectancy (though the NGK are "rated" for 100k)

the thinner the electrode, the more performance

copper is inexpensive, but is the least capable in either category

check out sparkplugs.com for more info

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[PhilG968]

I like Flash's recommendation as well.
I've been using Denso Iridium plugs for the last several years, and I feel they have performed better than anything else I've used. They are not cheap though, but last a long time.
They have become impossible for me to get other than on the internet lately.

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[wiseman]

This thread had me thinking about some new plugs also. Went to the Autozone site and looked both NGK and Autolight .....both iridium plugs. NGK #6637 is $2.99. Autolight #XP63 is $6.49. Does that NGK price sound right?

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[968rz]

$6.99 everywhere else I can see.

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[rl968]

The proper plugs are the one's with three-prong electrodes. I just replaced mine using bosch super plus. Copper is fine, just replace them every few years.

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[flash]

"proper" is subjective

as for "every few years", that depends on how many starts and stops, and how the engine runs - copper plugs are generally good for about 10-15k in a car like this during normal driving - after that, the performance really falls off

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[Johannvb]

I have recently installed NGK Iridiums and I really like them. The engine sounds smoother, but I do notice it stumbles for about half a second when I start it.

Definitely recommended!

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[Lear35A]

If your plugs are not oil fouling and there is not some other weakness in the ignition system, I don't see how iridium could give the slightest performance advantage. The plug lights the fire at the right time or it doesn't.

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[flash]

take a look at sparkplugs.com - it will explain a lot - it does make a difference, though you may only see it on a dyno on an otherwise stock engine

where it starts to make a difference is on a modified engine (i.e. chip airbox, etc) - you'll notice a distinct improvement in throttle response

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[Lear35A]

At least for stock engines, I am still skeptical about any quantifiable improvements in horsepower, torque, "throttle respone", starting or whatever by changing from what Porsche recommended when they built these cars. sparkplugs.com is a retail seller of spark plugs. Their site does a good job of explaining the different types plugs, but I can't find anywhere on it where they are specific about what a "high performance" spark plug can do to improve the performance of a stock engine.

I do agree that certain plug types can last longer. I do agree that certain plug types can help overcome problems with stock engines (like oil fouling). I agree that using the wrong plug can be detrimental. However, for a stock engine in reasonably good condition there is no free lunch from a change to a more exotic (read: expensive) spark plug. <i></i>caveat emptor<i></i>

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[flash]

definitely no free lunch, and as i said, likely no difference you could see anywhere but on a dyno (and even then it is small) - i have dynoed plugs before (not on this car though), and i have seen a gain from copper to iridium, but it was small - the only real difference was in throttle response - it was just a bit snappier - this was with new plugs of both types too

now, when you start playing with the timing and mixture, as in the case of a chip and airbox mod, you will start to be able to take advantage of the gains

the physics is there, but you have to have the right situation for it to make a difference, and even then, it isn't huge - it may not make sense for a lot of people - it makes sense to me, because i don't want to leave anything on the table - for a commuter, low cost probably makes more sense, though i think a longer lasting plug than copper (you would be amazed at how quickly they lose performance, but so slowly you can't feel it) would probably still end up being less expensive in the long run

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[mefforddk]

So when I purchased my car in 2004 I performed a tune up to included the iridium plugs. The car seemed to develop a stumble when cold. Afterwards I had a guy in Santa Clarita do some alignment work and he suggested copper plugs because they will typically burn hotter/faster. I changed to copper plugs and the stumbling was greatly reduced. Once I installed the RS Barn stage I chip did the stumble completely go way. Just my experience.

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[TWR]

Interesting and subjective as many subjects often are, but flash is correct that "A" difference is factual with the thin electrode iriduium types, and of course whether folk can feel any such difference is not often the case from the driving seat, but with all due respect it's only natural that some drivers are more sensitive to feeling changes than others.



I;ve just fitted a set of KV85 Magnecor leads and denso iridium .4mm electrode plugs, I await for a new idle stabilisher valve to turn up within a couple of days then I can give the car a road test and see if i notice any changes!



Regards, Roger

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[RS Barn]

We work on 968's every day and see every type of plug and every condition.

The triple electrode plug from Bosch lasts a long time. This is due to faily equal wear to all three electrodes. Single electrode plugs wear much quicker and require re-setting the gap to maintain performance and longevity.

The 968 ignition seems to have very high Voltage and burns up plugs (other than 3 tip) caps and rotors.

So new Single electrode plugs may have stumble when cold due to worn Cap and Rotor.

I also noticed 968's like a colder heat range plug, especially when run hard. These do need abit more warm up.

Putting holes in airbox also change cold warmup.

Let the car warm up a bit before punching throttle....

BTW-The DME restrics performance until oil warms up. It's all built in

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[PhilG968]

I'm using Denso Iridium, and they seem to last a long time with no issues. I find the response is quicker and when I changed the last set it wasn't because I felt there was any problems, I was just getting ready for winter with a new cap and rotor as well. Probably put 100,000 kl on the last set, with no noticeable reduction in performance. Again I do a lot of highway, maybe that helps!

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[TWR]

Just tested the new Magnecour Leads and denso Plugs, the car seems quieter on tickover???? And it also seems to sound smoother.



The idle surging problem seems to be better, but not totally gone, and I'm not 100% convinced but the top end RPm seems a bit sharper? could be psychological though..!!



A dyno before and after may show some differences and as mentioned before small differences may not be flet, but ass a few of them together and the total increase can be worth doing.



Sounds like RS Barn have been busy and also found some substancial gains from this normally aspirated large 4 pot! <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />

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[kmckmc]

How about NGK BPR6ES 7822 ? Should I give it a try?







Thanks.

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[kzem1]

NGK IRIDIUM IX BPR6EIX #6637

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