spark plugs

[srjs28]

i have not bought any type of "high performance" spark plugs for a vehicle since the split fires came out like 20 yrs ago. is there a plug that is recommended these days or will just a plain old autolite do?

 

[BigmacK192]

E3 Diamond Fire is supposed to be the new hi-po plug, but I still run Motorcraft coppers in my 5.0. You don't need much else.

 

[Cobra1741]

ngk or motorcraft copper

 

[HISSIN50]

Another vote for Motorcraft copper.

 

[tannerc91gt]

Autolite 23s for me.
Stock would be 25s.
Here's a decent reference sheet, it's a guide for nitrous plugs but you get the idea
nitrous plugs quick reference guide - Corral Forums

 

[Mustang5L5]

Motorcraft copper.

Same plugs as autolite, but specs are rumored to be tighter. They are not made by the same company..but are made by same tooling.

If you have boost, or serious mods...NGK iridium

 

[srjs28]

thanks guys, very helpful. since ive owned my fox (almost a year) ive turned to this forum for all my questions and 99% of the time they are answered and responded to with knowledge. thanks again.

 

[Slatco]

Does anyone have any input on the Denso Irridium plugs? Richard Holdener ran them in the 427 Paxton supercharged motor in last months "Muscle Mustangs and Fast Fords"

 

[Mustang5L5]

The benefit of iridium plugs is that because it has such a high melting point, the spark plug tip is much smaller. As a result, less voltage is needed to actually cause the spark to "jump" the gap. It's less strain on the ignition system.

On a stock N/A car i would not bother...but get up there in mods or forced induction and i would go with Iridiums

 

[Hi-Po]

After I installed the supercharger I had some slight detonation problems, but a set of Denso Irridium plugs took care of that. I was running the stock E7 heads then.
Last year I installed Trick Flow alu heads and went with a set of NGK copper plugs instead of the Denso plugs and they seem to work just fine. No detonation at least.

I remember the irridium plugs were incredibly expensive, but on the plus side they also had extremely long replacement intervals.

Anyways, I dont think you will gain any performance with irridium plugs, but if you are running high boost/spray then they may help with detonation/pinging.
Otherwise I would say go with good quality copper plugs.

 

[Mustang5L5]

Or silver plugs if you are like me and drive 500 miles/year

 

[7upstang91]

After I installed the supercharger I had some slight detonation problems, but a set of Denso Irridium plugs took care of that. I was running the stock E7 heads then.
Last year I installed Trick Flow alu heads and went with a set of NGK copper plugs instead of the Denso plugs and they seem to work just fine. No detonation at least.

I remember the irridium plugs were incredibly expensive, but on the plus side they also had extremely long replacement intervals.

Anyways, I dont think you will gain any performance with irridium plugs, but if you are running high boost/spray then they may help with detonation/pinging.
Otherwise I would say go with good quality copper plugs.

I emailed NGK about this issue last month. They did not recommend the Irridium plugs at all. Just email them all you have and they'll help you out!