Pulled my plugs

[351inside]

so today I pulled the plugs on my car to switch them out for sone brisk. Reason I switched is because im going to spray 100 shot on my car. From what I have been reading my plugs are in good shape, I have to admit when I was pulling out number 8 I was a little nervous, but it looked just like all the others...

Now im not an expert on this so thats why I want to post pics of the plugs so I can get some input, here they are. Im only posting four, all others look like the others.

Ive also sprayed a total of 3 times on these plugs, it was only a 50 shot though.


#1(first plug on the passenger side head)

#4(last plug on pass side)

#5(firat plug on driver side)

#8(last plug on driver side)

 

[BlackMamba03]

They look good to me. Like you, I'm not an expert but I've seen guys with far worse looking plugs. How many miles are on your car?

 

[Full_Tilt]

They look fine.

Reading plugs nowadays is mostly just for looking for detonation or to see if youre burning oil. If youre concerned with AFR you need to monitor AFR with the WBO2 sensors.

Remember that nitrous is not stoich with petrol at 14.7:1, its stoich at 9.6:1, so you have to take that into account when deciding what your target AFRs will be.

 

[back n a stang]

Look great!

 

[351inside]

My car is real close to 15k miles

 

[VTXFrank]

Those look close to perfect to me. If anything, I'd say you were running a tad lean. But the run with the giggle gas can do that. I think the #8 plug represents what all of them looked like before the Nitrous runs.

 

[Jim Vaccaro]

Look good to me!!!

 

[SteveP]

They look good.

 

[Rynez06]

They look fine.

Reading plugs nowadays is mostly just for looking for detonation or to see if youre burning oil. If youre concerned with AFR you need to monitor AFR with the WBO2 sensors.

Remember that nitrous is not stoich with petrol at 14.7:1, its stoich at 9.6:1, so you have to take that into account when deciding what your target AFRs will be.

lol what? nitrous is stoich is 9.6:1?? actually nitrous doesnt have a stoich because its a oxidizer... adds oxygen when added to a combustion process.... this is why you add fuel at the same time, there for stoich is unchanged from whatever fuel you are running.... sounds to me like you are confusing nitrous with e85 fuel which has a stoich of 9.7:1 versus gas's 14.7:1....

 

[Full_Tilt]

lol what? nitrous is stoich is 9.6:1?? actually nitrous doesnt have a stoich because its a oxidizer... adds oxygen when added to a combustion process.... this is why you add fuel at the same time, there for stoich is unchanged from whatever fuel you are running.... sounds to me like you are confusing nitrous with e85 fuel which has a stoich of 9.7:1 versus gas's 14.7:1....

Not quite, but I can see how my language is misleading.
Petrol is is stoich at 14.7:1 with air, which means that 14.7 mol of air is needed to fully combust 1 mol of petrol. The oxydizer plays just as much of a roll in stoichometry as the fuel does.
Since nitrous has more oxygen by mass, its stoichometery of combusting petrol is different than that of combusting petrol in air.

If you calculate the stoichometery of pure nitrous oxide reacting with pure iso-octane, you find that its at a ratio of 9.6:1.

This means that if youre making 400hp NA with a target AFR of 13.5:1 and then you spray a 100 shot of nitrous with a weighted AFR of 13.5:1 (which would read as an actual AFR of 8.82:1), you would want youre target AFR to be ~12.5:1
This would be the equivalent of an NA engine being at 13.5:1
Without this understanding you may run the 400+100hp nitrous engine at, lets say, 13.0:1 and it would be unnecessarily (and probably dangerously) lean.

 

[2012GT]

Full Tilt will cure cancer!

 

[Full_Tilt]

On a related note, this is the very reason I suggest monitoring EGT when spraying. Not only do target AFRs, that we take for granted, not hold up, but Im not 100% confident of the accuracy of the sensor when used like this.
I cant tell you how many times Ive heard "The AFRs were fine when spraying, but it melted a piston/valve/etc." usually followed by "Ill never use nitrous again, its too dangerous".
EGTs wont lie, it will tell you when you are lean regardless of what fuel or oxider is. If only they would have had an EGT guage, they would ahve seen that they were in fact lean, even if the WBO2 and their preconceived idea of okay AFRs told them they were not.

 

[Rynez06]

Not quite, but I can see how my language is misleading.
Petrol is is stoich at 14.7:1 with air, which means that 14.7 mol of air is needed to fully combust 1 mol of petrol. The oxydizer plays just as much of a roll in stoichometry as the fuel does.
Since nitrous has more oxygen by mass, its stoichometery of combusting petrol is different than that of combusting petrol in air.

If you calculate the stoichometery of pure nitrous oxide reacting with pure iso-octane, you find that its at a ratio of 9.6:1.

This means that if youre making 400hp NA with a target AFR of 13.5:1 and then you spray a 100 shot of nitrous with a weighted AFR of 13.5:1 (which would read as an actual AFR of 8.82:1), you would want youre target AFR to be ~12.5:1
This would be the equivalent of an NA engine being at 13.5:1
Without this understanding you may run the 400+100hp nitrous engine at, lets say, 13.0:1 and it would be unnecessarily (and probably dangerously) lean.

i am sorry but i disagree, it adds oxygen to the mixture like any other form of forced induction... you are using petrol there for the stoich is still 14.7, but you enrich the mixture because of the added cylinder pressure and heat there run it more rich then in a NA application.... with your logic i would assume when you turbocharge or supercharge an application your stoich changes as well.... your "idea" is correct, but your getting using the wrong path.... but what do i know i only tune cars for a living.....

 

[Full_Tilt]

Thats completely different.
Any way you are increasing VE, be in forced induction or NA tuning, you are still using air, which means that the amount of oxygen is proportional to the amount of nitrogen in the air.
The stoichometry is completely unchanged, youre just changing the volume.

Nitrous oxide DOES have different stoichomety because the mass of oxygen is proportionately larger.
Air is 23% oxygen by mass (21% by volume), Nitrous oxide is 36% oxygen by mass.

You are thinking of a O2 sensor as if it is actually measuring AFR, It is not.
Its measuring the amount of oxygen in the exhaust in proportion to the amount of oxygen that is in the outside air. Its essentially calibrated to assume that the oxidizer being ingested by the engine is air, so when youre using a different oxidizer, with a different proportion of oxygen, the reading is not the same.

 

[UltraKla$$ic]

It's all clear as mud now!!!! Thanks! LOL!!!