Just purchased 05 coupe 6MT, and am looking to improve performance without compromising reliabilty. The coupe I purchased has an aftermarket s.s. exhaust. I'm installing R1 premium, slotted, and drilled rotors with Posi-Quiet ceramic pads. The car has 66k miles. Should I replace the plugs, and if so, with what? Any other thoughts for performance without major mechanical work?

 

You posted in the sedan forum. As for plugs, Denso or ngk, platinum or iridium. Performance, if you do al bolt ons, plenum spacer, intake, headers, exhaust, high flow cats. You will probably get 15-20 HP without a tune, 30-35 with. With all the bolt ons you need a tune or you will run lean.

 

Thanks. I've read that people have had issues after they replaced plugs. Is there anything unusual about replacing plugs in my coupe?

 

There are plenty of instructions on this site and others. Your plugs are probably fine though, I just replaced mine at 100,000 and they looked pretty good. Also, you will not get any performance gains from using one plug over the another.

 

I usually search the internet and then check rockauto. They almost always are the cheapest. I bought ngk iridiums from there the other day and got a good price. They also have coupon codes that get you 5% off. Usually helps to pay for shipping.

 

NGK oem, platinum iridium

 

Has anyone dyno'd different plugs at all?

Curious to see what benefit NGK has over standard copper, for example. Let alone the benefit between the high end plugs.

For example...

http://www.carsdirect.com/car-repair...op-performance

States that copper is the best spark plug material, which is logical due to the uses of copper in other components and it's propensity to be stolen for it's value.

Unless we're looking at NGK (for example) it uses a copper core and plat/iri to scale back the charge and add longevity?

I'm spitballing here, wanting to learn the actual WHY and real world applications of what we use.

 

Additional information:

http://community.familyhandyman.com/...-the-myth.aspx

I read a lot of online auto blogs and continually see folklore “wisdom” that copper spark plugs are a better choice than either platinum or iridium. Rubbish! The myth is based on the fact that copper is a better electrical conductor than the more expensive precious metals. That’s true, as far as it goes. But there’s far more to creating a powerful spark than just the conductivity of the electrode material.



The myth ignores the fact that an ignition spark always jumps from (and toward) the sharpest parts of the center and side electrodes. Sure, a copper spark plug has sharp electrodes right out of the box. But copper can’t maintain sharp edges very long. The heat of the spark itself and high combustion temperatures quickly wear down the edges of both the center and side electrodes. That’s because copper has the lowest melting point of all the currently available spark plug materials (copper melts at 1,983 degrees F, yttrium at 2,779 degrees, platinum at 3,222 degrees and iridium at 4,229 degrees). Copper plugs actually experience rapid edge wear and increased spark plug gap in as little as 10,000 miles. And that results in a far less powerful (and less effective) spark that can misfire, lower your gas mileage and damage ignition wires and the coil.



Premium spark plugs, on the other hand, hold their sharp edge and maintain the proper gap for up to 100,000 miles. With the highest melting point of all the precious metals, iridium-tipped spark plugs are now considered the best choice for quick starts, solid acceleration and overall long-term performance. So ignore the myth of the copper spark plug and spend a few extra bucks on a premium spark plug.

 

ngk 6240

 

^^^ what he said


Laser Platinum
Laser Platinum® spark plugs provide high ignitability and longer service life. Dual platinum surfaces ensure slow wear rate providing stable idle, superior anti fouling, improved fuel efficiency and lower emissions.

Laser welded Platinum center electrode tip
Platinum disc welded to backside of ground electrode provides long life
Trivalent Metal Plating provides superior anti-corrosion and anti-seizing properties
Faster starts and quicker acceleration
Better fuel economy and lower emissions

 

ngk iridium all day!

 

Jstudrawa

Copper is a superior conductor of energy over platinum or iridium. However copper plugs are usually only good for 10-15 k miles. If this was a 4 cylinder with a 10 minute plug change it would be a great option. Since the time needed to change plugs on this car is a lot more, most go with longer lasting iridium or even longer lasting platinum.

Copper might give you 1/10th of a HP over iridium and 1/4 over platinum and similar mpg improvement. Not worth the hassle to change plugs every 10k miles.

 

FYI
OEM
Specification:PLFR5A-11(STD OEM)
$68 for set shipped

 

Agreed.

With a modern ignition, the difference between copper and Platnium is negligible when the ignition system was designed with the higher resistance Platnium in mind.

There really is no reason for the question these days. Unless you want to change plugs every 10-15k miles, stick with the oem Platnium plugs. I changed my OEM plugs at 110,000 miles. They were worn, and I noticed a 1mpg improvement afterwards.

I do find my mustang runs better on copper plugs than platniums. But it also takes 10 mins to change those plugs.


Edit: there are silver spark plugs as well. But their use is more specialized, and not really for everyday driving.

http://www.summitracing.com/search/p...er-spark-plugs