Recommended spark plugs on E85?

[DaymienS550]

Im getting close to 20k miles and am gonna change the plugs out soon just as a precaution. Does anyone have recommendations for plugs that i could buy that will be used for running E85? I plan on going boosted in a few months as well so preferably ones that will also work for boosted applications if not no big deal ill just swap them again when i boost. Also are you guys gapping to stock specs? Thanks in advance!

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[HKusp]

If you're going boost I would check with your tuner, but I'm betting they say NGK 6510's and gap them at .028

 

[DaymienS550]

If you're going boost I would check with your tuner, but I'm betting they say NGK 6510's and gap them at .028

Thats what i was looking at. Will those also be fine NA for the time being?

 

[GregO]

I’m thinking GT500 NGK spec. plugs gapped at .037”

 

[HKusp]

Thats what i was looking at. Will those also be fine NA for the time being?

The gap might be a little tight for N/A applications. If you are currently only coming up on 20K, in "normal" daily driven use, I believe Ford doesn't recommend a plug change until 100K miles, so you should be alright until you actually go FI.

 

[DaymienS550]

The gap might be a little tight for N/A applications. If you are currently only coming up on 20K, in "normal" daily driven use, I believe Ford doesn't recommend a plug change until 100K miles, so you should be alright until you actually go FI.

Even if I’m running E85 90% of the time?

 

[K4fxd]

Even if I’m running E85 90% of the time?

Shouldn't matter.

The old points cars ran .28 to .32 plug gaps. I'm running .30 on my N/A GT. I think it makes the coils last longer and it will fire at 8000 RPM reliably.

 

[GregO]

I’m N/A @ .032”ish smoothed it out from the factory wide gap. 50K miles on that gap.
But now the platinum grounded GT500 NGK’s #7 heat range have my attention.

 

[FrankRussel]

F8S should be standard issue plugs on full E85 cars..97506 are good for pump gas but timing won't be clean as F8S on E85..

 

[GregO]

F8S should be standard issue plugs on full E85 cars..97506 are good for pump gas but timing won't be clean as F8S on E85..

Wrong seat type, wrong thread, wrong reach.

 

[Need4SpeedMotors]

2016 GT vortech car with fore innovations fuel system and E85. I did NGK 6510 gapped at .026. No issues. Car has been running great the past year.

 

[ice445]

Shouldn't matter.

The old points cars ran .28 to .32 plug gaps. I'm running .30 on my N/A GT. I think it makes the coils last longer and it will fire at 8000 RPM reliably.

You want the widest gap you can get, it results in a more complete burn. NA means stock plug gap in my book. Boosted needs tighter gaps to avoid blowout.

 

[K4fxd]

You want the widest gap you can get, it results in a more complete burn.

Up to a point. If all you need is .024 gap and you use .06 you are just working the coil too hard. The wider gaps will blow out at high RPM if the coils can't keep up. .03 to .035 is plenty for a N/A engine

 

[ice445]

Up to a point. If all you need is .024 gap and you use .06 you are just working the coil too hard. The wider gaps will blow out at high RPM if the coils can't keep up. .03 to .035 is plenty for a N/A engine

I get what you're saying but I don't agree that .035 is "plenty". Ford clearly had a reason to spec .050. If less was good enough they could have saved some money on coils. I agree its not going to matter much in practice, but I just prefer following the spec.

 

[GregO]

I’ll just put this here for anyone interested. I’m still processing it.

https://iopscience.iop.org/article/10.1088/1757-899X/160/1/012044/pdf

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