Gen 3 spark plug debate??!

[mustang88_cars]

I have read plenty of information in regardes to older Gen 3 coyotes coming with heat range 7 plugs from the factory then Ford changing to heat range 6 plugs after 2021 and making it a backwards to 2018 recommendation

So what’s the consensus? Use the heat range 6 SP-589 or the heat range 7 sp-548?

For context I purchased an 85 Mustang GT Gen 3 coyote swapped car with a CAI, IMRC lockouts, and BBK long tubes. It wasn’t tuned very well if at all. I got it tuned and just want to change the plugs for peace of mind after running the car on that crappy tune.

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[cbrtrx]

The 7's still work great for NA.

 

[Optimum Performance]

The 548's will work but the 589's are what is in G3 Coyotes due to the potential for higher combustion temperatures with DI and compression. Not really certain how different they are in actual heat range. Information is spotty.

 

[mustang88_cars]

The 548's will work but the 589's are what is in G3 Coyotes due to the potential for higher combustion temperatures with DI and compression. Not really certain how different they are in actual heat range. Information is spotty.

That’s good to know. I’ve gotten a lot of differing info on heat ranges of both those plugs from AI. No surprise there.

I went ahead and ordered the 589’s but generally what I was seeing is that folks think the 548’s are a little cooler and should be better for the high compression gen 3. I’m no engineer though but it does seem weird to change the plug number half way through the generation cycle. It’s Ford so it’s not that weird

 

[John S]

I switched to E85 on my naturally aspirated 2022 Mach 1 and I have no intensions of ever going back to 93. Is the optimal plug gap and heat range still the same as stock?

 

[robvas]

I switched to E85 on my naturally aspirated 2022 Mach 1 and I have no intensions of ever going back to 93. Is the optimal plug gap and heat range still the same as stock?

Yes.

In theory you could get away with a slightly hotter plug on e85...

 

[cbrtrx]

I switched to E85 on my naturally aspirated 2022 Mach 1 and I have no intensions of ever going back to 93. Is the optimal plug gap and heat range still the same as stock?

I like to run .045 gap on NA with e85. I've had better results that way.

 

[Noleftist]

THOUGHTS? Which is it?
I bought from Rock Auto
Per NGK.com: GAP at .032 Ruthenium
SKU #LTR7BHX
ITEM #NGK95605

BUT then I see other sites: The recommended spark plug gap for a 2022 Mach 1 Mustang is 0.048 to 0.053 inches.
I also see another plug is recommend: NGK6509 (LTR6IX-11)
I would guess there are other recommended plugs also.
If your Road RACING also does the heat rating/range of the plug matter if you’re naturally aspirated?
Gap for same use as above?

2022 MACH 1 w/hp ENGINE IS STOCK. Road race and grocery getter above 50°F.
98% of the time Costco 93 octane

https://ngksparkplugs.com/en/part-finder
recommends a Laser Platinum LTR7CP13 at GAP 0.052 INCH
and a Ruthenium LTR7BHX at GAP 0.052

I have read on the Internet, where some sites claim Ruthenium gives you better performance and better longevity. But then others claim that it is decreased longevity.

Thank you.

 

[Noleftist]

I also read and have been told it is best not to change the gap on Ruthenium due to it is likely to fail/break!

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