Contour Enthusiasts Group Archives Forums Modifications Duratec Performance NGK Iridium plugs

I know from past posts that there are some cars running NGK Iridium plugs and was wondering if there is a consensus as to their suitability and would you use them again?

Rules for Spark Plugs 1) You dont get any more power by changing the plugs,can loose power with the wrong plug but recovering lost power isn't a 'gain. 2) The make of plug also has no bearing on power, gap and grade have to be correct ,the engine does not know which brand of plug it has! 3)Multiple ground plugs(+4 etc) offer a longer service life...nothing more 4)Precious metal plugs offer increased efficiency because electrodes can be thinner and gaps larger which will reduce misfires & improve starting.They do not give more power 5) Cannot improve cylinder burn with a diffrient plug design, once the mixture starts to burn the spark is long gone 6)Color of plugs tells little,main point on plug selection should be heat range...

Great response, Terry! You are a Gentleman and a scholar... a Prince among men...
(But I KNOW I get at least 10 more ponies from the NGK sticker on my rear bumper alone! jus' think what a couple more on the sides of my ride will do!!!!! )

Terry, I don't disagree very often, but in this case I can't help it. The make of plug can (and often does) have a bearing on an engines performance and the reason falls under the quality of materials within the various brands of plugs. A prime example is NGK Iridium Plugs versus Denso Iridiums. Denso's on average will produce 9-10hp less on a dyno then the NGK equivilent, not to mention they don't last near as long as the NGK's either. The reason is behind it falls within the material quality, not design. Plug make is more important then most people think, and seeing what's lying around in our returns/warranty department only comfirms that.

Also you said it yourself that the prescious metal plugs offer greater efficiency...
under load and high rpms greater efficiency can allow for more power and an overall increase in performance.

To answer Alex's original question about the NGK's
The NGK Iridium plugs are a great plug and aside from the price of them we have yet to get any real complaints about them.

-Mark

And SOMEBODY was supposed to have a salesman get in touch with me about those and failed to do so!!!! I won't mention Mark's name though!

My Bosch +4's lasted all of 15k miles...I'd avoid those at all costs

Mine are working just fine...

High compression, chip, hard driving and all...

Hope you atleast got your money back???

Not saying I think they are the best IMO, but they do work just fine...

I don't think that it is likely that Contique owners will find a source for Denso plugs, but I'll pass on something I learned recently.

Our dealership also sells and services Suzuki automobiles. An "unofficial" comment from their tech hot line was to avoid Denso plugs as they sometimes cause wierd drivability problems. We have made it a point to avoid them ever since.

I agree with Terry. As long as the plug is free of defects and not worn out, the engine does not know what plug is in it. Stories about how Split Fires or other unusual designs generate more horsepower is pure "snake oil".

Mark, if you read the reference to 'heat range ' etc one make of plug is usually better than another only because its range is in line with the requirements of the engine...so again any make is fine as long as that heat range is correct...and just to rub it in , when did anyone on this forum buy/ask for an aftermarket plug by giving its 'range' eh!!1 I doubt it bud!(PS I've seen hundreds of spark plug tests on dyno cells in Ford Dunton ,trust me brand X is as good as Brand Y if its range is correct!
)

I'm sorry Terry, but I said nothing about heat ranges. My main disagreement with your statement(s) is brand doesn't matter. It Does! Ask yourself this, Do you buy a product that lasts/performs for 6 months or one that lasts/performs for 12? Quality of the materials and manufacturing process will play a factor in any part whether its plugs, pistons, brake rotors, turbos, etc, etc...

I'm sorry, but when I go back to our returns department and see stacks of Accel & Autolite spark plugs all with defect tags on them and little to no NGK plugs on the return shelves that says something to me.
-Mark