blow thru

Hi guys gave my Ls1 its first hit with a 100 shot yesterday and was very pleased on the outcome.

Everything is standard except full 1 5/8 4-1 headers and twin 2 1/2'' exhaust and K&N filter

Nitrous Outlet Fogger
52n 28 fuel
Br7efs gapped 35''
Standard timing
98 oct pump fuel
Bottle pressure 950
Wideband averaged around 11.8-11.9 during the pull
Pulled over on side of the road put a new plug in gave it a hit and shut if of straight away,put old plug in and drove home

Any suggestions would be helpfull.

soundengineer

iTrader: (16)

"Ground Strap" = Heat Range

If the "color" of the strap changes near where it is welded/attached to the base ring (last thread ring), then the plug heat-range is "too hot", because heat is not being transferred or cooled from the strap to the base ring quickly enough. The strap might begin to act like a "glow-plug". Eventually causing pre-ignition and/or detonation later on. The proper heat range is when the "color" is at the half-way point on the strap. This means the plug is neither too cold or too hot.


"Plug's Base Ring" = Fueling

The air/fuel mixture ratio shows up on the base ring. This is the last thread ring, it has the strap welded to it. You want a full turn of light soot color on the base ring!!! If you want to tune for maximum power, then you want 3/4 to 7/8ths of a full turn of light soot color to show up on the base ring. This is on ragged-edge of being too lean, but will make the most HP in most engines. To be safe, leave it at a full turn of light soot color. If the base ring has a full turn of color, but there are "spots" of heavy build-up of "dry soot" on top of color, then jetting is too rich.

If the base ring has a full turn of color with some spots of heavy dry soot, then jetting is too rich, REGARDLESS, if the porcelain is "BONE-WHITE", jetting is still TOO RICH.


"Porcelain" = signs of pre-ignition/detonation

To look for the first/beginning signs of detonation, search the white porcelain for tiny black specks or shiny specks of aluminum that have fused to the porcelain

soundengineer

iTrader: (16)

might not have enough time on the plug

your ground strap would indicate that it is the correct heat range plug from what I can see...
cant tell on the top ring from the picture..
and looks like you dont have any detonation.

Doug G

Get better pics

blow thru

Hope these are a bit better photos,i like the idea of being on the safe side atm till i get a tune.

Doug G

Slightly hot and a little lean IMO But plugs may be too new ?

What fuel,timing,jetting ?

blow thru

Premium 98 oct pump fuel(Aust)
Timing- unsure as factory
Jetting-52n 28f

Golf&GM

iTrader: (22)

Just to clarify, I never understood what a full turn of color on the base ring meant. Does that mean that the soot is evenly coated all the way around the ring so none of the metal is showing? From the second set of pictures I can't see any change in color, but it might be the glare.

soundengineer

iTrader: (16)

I dont care about actual timing values....it doesnt matter if its 12* or 35*... it different in every motor, every system, every climate...

as long as you dont see signs of detonation on the plugs...its all good

it honestly looks like you dont have enough time on the plugs...
I think I'm starting to see speckles of black on the ring, which would indicate being rich....but its Just too hard to tell from the pictures...too much reflection

the strap looks like its turning colors in the right places,
but again.. I dont think you have enough time on that plug to tell for certain..

soundengineer

iTrader: (16)

"Full Turn of Color"
means a light soot layer is covering the entire base-ring of the Plug

the base-ring is the last thread ring that has the Ground Strap
welded to it.

if you only see approx. half or 3rd a turn of Soot deposit,
you are too lean for most applications

if you see a Full Turn of Soot deposit, but its much darker and thicker,
its probably too Rich for most applications to make its best HP/TQ
Numbers


and in this particular car's example.. I would guess that his 11.8/11.9 is too rich...and he doesnt have enough time on the plugs to tell from the plug itself

blow thru

Yes true,its had no idle time on that plug just a hit and shut down.I will get another pass down when i can with maybe couple of minutes idle time.But not much difference goin to the track short burnout pre-stage then do a full pass shutdown.There were probable 3 tiny black deposits on the porcline.

03supercobra

iTrader: (38)

You might be a little mis-informed. The strap of the spark plugs shows where the timing is, add timing it goes toward the weld, subtract and goes towards the tip.

The porcelain is where the fueling is read off of.

soundengineer

iTrader: (16)

I'm fairly certain fueling is not not read on the porcelain...

the strap tells you what kind of heat is being held.... when its too cold it moves towards the tip, when its to hot it moves towards the weld...

changing timing will have the same effect as changing the heat range of the plug

more timing usually means more heat...and vice versa...

blow thru

You just answered my own question, i was wondering which way the timing mark went on the strap with adding and pulling.Thanks

03supercobra

iTrader: (38)

Your kinda going in the right direction, but on nitrous stuff it is known approximately what heat range plug per nitrous amount. As you add timing you will see it in the strap, that doesn't mean you need to change to a colder plug.

The fueling is read on the porcelain, seems like your thinking old school carb tuning with idle and part throttle tuning.

03supercobra

iTrader: (38)

I didn't realize changing to a colder plug made the ignition fire later.

Doug G

Cooler plug should only transfer heat away from the plug faster...shouldn't change timing but could change marks on strap I guess ? (but I wouldn't think much)

One thing that I was looking at was the discoloration in the cut-off threaded part (looked like a lot of heat ...purple/blue/gold)

soundengineer

iTrader: (16)

I didnt say changing to a colder/hotter plug changes the timing....
I said it changes the amount of heat the plug generates...

on a colder plug you can get away with more timing as it is less prone to pre-ignition...
you still are limited by the actual MBT... but its not as likely to fire early because its holding too much heat..

on the same account... you can use a hotter plug, with less timing...again..not ideal...
but you can stave off pre-ignition by pulling timing when you have too hot of a plug
Further away from MBT you get, the less cylinder pressure you get, and the less heat it produces..

wh do you think our cars are set up to pull timing when they start to overheat...
its partially to try to cool down the spark side of it to compensate for the engine side of it..



and the info I posted about how to read a plug many posts above was a copy and paste from something Chris@nitrousoutlet has posted many times....

you dont read Fueling from the porcelain..it is not accurate because of many other factors.

Doug G

I do know it takes longer to get a good color with this 10% -15% ethanol BS

And I look at the base ring (non-existent on there)

SargeZ06

And that is exactly how most on this board say you should do it. I think you will need a full 1/4 mile run to get the ring to show up though. I never could on an 1/8 mile pass.