E85 spark plug question

[99 gst spyder]

Just done with dyno and everything went great.. I have bpr7es while dyno/tune and now I seem to get spark blow out or major stutter when full boost and in the high rpm level at 5k plus to redline... Gap at .24.

So my question is how often am I suppose to change it or am I suppose to change it right after the dyno?

 

[Derail20T]

When I had my car tuned on E85 at forced Engineering, they gapped my plugs to .018". I had them gapped at . 024 previously, but it was stuttering in high rims. It's worth a shot to regap your plugs.

 

[boost97gst]

On e85 you are just fine with br7(I would personally try BR7ES, w/out the P). I think its something to do with the temp of the fuel. Gas is hotter therefore people move up to br8,br9. E85 burns cooler so Br7's are ok. Anyway, thats what i was told a year ago or more by several people.

At 30+ psi i would have to gap down to what Derail said: .018. Just fyi.

 

[jakelandry]

I've run my car at 30+ psi for years now with all my plugs gapped at .026 without a single misfire on ANY plugs. If your gap is at .018 something is abnormal.

 

[My1GLaser]

How much boost are you running?

I also run non-projected plugs (BR8ES) gapped at .018". I replace plugs about twice a year for $10 a set...

I have also had plug wires suddenly "go bad" and cause spark blowout. They looked fine, but when I replaced them with new ones the issue stopped immediately.

 

[99 gst spyder]

How much boost are you running?

I also run non-projected plugs (BR8ES) gapped at .018". I replace plugs about twice a year for $10 a set...

I have also had plug wires suddenly "go bad" and cause spark blowout. They looked fine, but when I replaced them with new ones the issue stopped immediately.

I'm at 29psi now.... Is that too much for tuned stock motor! I'll try to regap them at .018 to .020 and see how they run... Then if not I'll get new spark plugs and or switch my wires...

 

[99 gst spyder]

I took the plugs out and this is what I found in picture here.

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[jakelandry]

Not to be negative, but you came on here asking about your spark issues without even pulling the plugs.....

 

[boost97gst]

Whoa.... runnin a bit lean? Those all the same age? I would be checking your knock sensor and making sure its working and next set of plugs i would do a pull and immediately shut the engine off and coast to a stop. Then pull them and "read". Thats just an old school trick. If those look that bad the combustion chamber/pistons/valves might have been burned as well.


edited out, just checked your profile, Jake. This new site, , im still fumbling a little. Its great though

 

[DSM1G90]

Wow ! .. someone definitely has a lean problem if you blew the ground electrode right off....

Alcohol has a lot less BTU (explosion) output than does dino fuels, where the plus side is the 100 plus octane that alcohol contains to prevent knock.

Why alcohol funny cars do it well ...

Thus, to get the same BTU as the dino fuels contains, we definitely need to rich up that E85 mixture with different fuel mods, mapping and settings.

 

[99 gst spyder]

Bought new plugs br8es and gap to .021 and everything ran fine.. Straight pulls to redline..