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ok i have iridium spark plugs on my svt are these good to run with 10 psi??
 

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Ok Joe im going to have to disagree , I installed the Iridiums in my car and did 4 passes on the dyno testing them against a set of AZFS22C plugs that have been in there for about 3000 HARD miles , same day with in about a 30 Min time frame

There was no gain and no loss , I kind of wish i had installed a new set of the 22C because in most cases new plugs show a slightly better TQ/HP

Take cost into account and the 22C is still the better choise

Tom
 

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Feel free to disagree, but I ran them in the wagon for a couple years...they work awesome and last for friggin' ever. They're like a durable racing plug.

Small electrodes work better...it's just physics. If you can find a copper plug with a small electrode, maybe it might work better, but I haven't seen those anywhere.

3000 miles is a lot for a plug????? I guess for a copper, it's a 20% of the life, but for a platinum or iridium plug, it's only 3%.

One (big ignition) company I know ran a durabilty test on thre iridiums on a blown motor with a mag on the dyno. They never wore them out, they said the plug was good until the resistor burned out(>5Kohm). They were quite enthusiastic about them...they take less voltage to fire...so you could actually open the gap if you wanted to, all other things held constant.
 

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Another advantage would be the larger gap which would give a bigger spark and a better burn of the fuel.
 

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Im kind of old school with my plugs and i cut the wire back to half the electrode is exposed , I have found 5 to 8 HP doing this on the dirt track cars much like the AR series autolites does now , This exposes more flame much like a smaller electrode does

I did try more gap because thats what the plug Co. said to do but got misfire much like trying more gap with the 22C plugs , I allways run as much gap as i can just before a misfire occurs

I wish from time to time I had installed a MSD and went for more plug gap but the stock ignition allways worked so well that I never spent the time or money to see how much better it would be and many of the customers that have come in with MSD we have had to lower the gap anyway

A MAG is kind of a far streteh from our coil pack as well , Altho i do beleive that the Avg. FI cars out there that dont change plugs often would be 100% ok with the Iridium, My thing with them is , If you change plugs often it will get very costly , I change and read my plugs at every race to watch what is going on and install new ones for the next race or event

If there in your budget run them they wont hurt a thing , If your a tight a$$ like me where i cannot justify the HP/TQ gain for the cost the 22C do a heck of a job

Tom
 

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FWIW, the question was whether they work, not whether they're cheaper...LOL

Every time at the track????? LOL...I think I ran the same 8 spark plugs for the wagon for two years. Still have them. I've been running NGK racing plugs and they're $25 each...if they're not burned, they're going back in. :)

The point about the mag was that if they hold up to an endurance test on a blown motor with a mag, they'll hold up to anything. Basically, the mag ended up burning out the resistor. When was the last time you heard of that happening? The plug was otherwise fine..they told me you could run them until the resistor was burned (>5K) and it would be good to go. Almost like a permanent spark plug, with no significant deterioration.
 

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kylebal said:
ok i have iridium spark plugs on my svt are these good to run with 10 psi??
So with the original question in mind. If he did want a longer lasting plug, but still wanted it to run very good. What heat range of iridium would u guys recommend. For both Zetec and SVT? I would think you would want a step or two colder plug than stock(in both the zetec and SVT) correct?
 

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Maybe one range colder...the thing I think people don't get is that the heat range concerns the plug, not the cylinder or the motor. If you blister a plug, THEN you need a cooler plug.

If it's extremely wrong, you could have a detonation issue due to the plug, but you'd see indications of that on the plug (blistering and indications of center electrode melting) long before that if you looked. Generally, you run the hottest plug you can make live.
 
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