JoeMama's GTO

iTrader: (3)

Wondering if I could get an assist on some plug reading. This is from a procharged (P1) LS2 running a 120 shot on E85. Total HP is right around 750 at the wheels. NGK 9 plugs gapped to .025, 17 degrees of timing, and 11.0-11.5 AFR. Did a pull in 5th gear because this car will be running a half mile event (shut off immediately after). The #7 plug has me concerned as it had some soot spots on it, not a total peppering but a few spots.

#8

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#7

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#2



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gtfoxy

I don't see any specling from Al. But it looks like 7 is certainly getting more heat into it.

You have to be real careful with E85 & juice. The temps nitrous brings can cause the E85 to separate from the low-octane gasoline. You'd be better off mixing straight Ethanol with higher octane fuel for that application.

JoeMama's GTO

iTrader: (3)

Hmm, I had never heard of that separation issue, I will have to look into a drum of E85. Any ideas why 7 was brownish on the ground strap?

rotary1307cc

iTrader: (5)

Good pics, shows exactly the kind of spread you can see on number 7

And why it will really show in a long pull like a half mile


Look at the base of the plug... That ring.

See how on the other two it hasn't changed but slightly in one area. Still shiny.

Then number 7 is burned the full circumference and moving up the threads(look inside too)

7 was about ready to say bye bye.

Other ones look great and safe.

Nice pics, thanks for sharing

rotary1307cc

iTrader: (5)

What ems are you running? And what nitrous induction?




Here are a pic of what I consider my ideal plug to look for.

These pics are all the same plug


See the half turn of heat? Notice the heat in the strap?

JoeMama's GTO

iTrader: (3)

Damn, what do you recommend? Go to a 10 plug on #7? Pull timing? I thought the pics sucked but if you can read them it can't be too bad. #7 has some soot/det speckles on one side and the inside of the threaded portion turned a dull grey for about 75% of the circumference.

JoeMama's GTO

iTrader: (3)

I am running the stock ems (E40) and a NOS plate for spray. I really didn't get the black/grey heat ring on the plugs. #2 and 8 show nothing there and #7 is rainbowed halfway around.

gtfoxy

Phase separation is not just what happens in the gas tank. It starts when any amount of water vapor is absorbed by the blended fuel. If subjected to extremely low temperatures the solubalized water vapor crystallizes. This can cause phase separation to occur mid-stream in the intake.

From a paper on the subject:
It doesn't happen often, but it can happen. It is imperative the fuel remain fresh, especially when combined with nitrous.

JoeMama's GTO

iTrader: (3)

Link to the paper on this? What is meant by extremely low temperatures for this crystallization? The fuel is as fresh as it comes from the pump, of which I have no idea how long it has sat in underground tanks.

gtfoxy

http://agronomy.emu.ee/vol132/13_2_32_B5.pdf

There is another paper I have read that deals with this to -25*C. It was a tad analogous to this papers findings. We know phase separation occurs even at around 30*F, so I am more inclined to discount the other papers findings.

I know lots of guys use E85 in conjunction with Nitrous. Most live happy lives but for the ones that go boom this may not be a known occurrence & it gets chalked up to other circumstances.

JoeMama's GTO

iTrader: (3)

I think the bigger thing to fix is venting the rear ports and opening up my exhaust. I am still on the stock catback which seems restrictive and the rear steam ports are not vented. If it was an issue with separation I would expect all cylinders to be in rough shape but it seems trusty ole #7 is the bad actor. Something to consider for the folks that run in a harsher winter though. It rarely gets below 30 in Atlanta and definitely never hits 30 in an underground fuel tank.

gtfoxy

No worries. I just wanted you to be aware of the potential issue. It is not a very known phenom, but one that needs to be considered due to the application.

Add: it's not ambient temp but the temp of the nitrous as injected into the engine. That cools the fuel, especially in a wet system, & can cause phase separation.

rotary1307cc

iTrader: (5)

You may be in luck. IIRC. Either the e40 or e38 has individual cylinder trimming on fuel and timing. I can't remember though, check into it

If you can't do indv. Trimming, then you need to back off the entire time until that cylinder is happy. No not ideal


If you can do individual cylinder it is as simple as pulling some timing out of 7. Ideal


Just be glad you checked plugs, well done

I believe the strap has that color because it of how hot it got, possible some det.

55superbeetle

iTrader: (5)

What type of run time are you putting on these plugs? One run and immediate shutdown? Learning a lot from your latest posts, would love to know your procedure.

rotary1307cc

iTrader: (5)

Yes correct. One pull and shutdown

You did it right. And you will have an engine because you did this.

Forcefed86

iTrader: (4)

In situations where you can't adjust individual cylinder fuel trims/timing you can run a colder plug in the problem hole. As well as flow your injectors and run the highest flowing injector in that hole.

You could also install some sort of water/meth injection. Then add additional jetting/cooling on the #7.

Good luck!