LS9 engine. 13lbs of boost. 200 shot pre blower. B8EFS plugs gapped at .028. 93 with Torco in the main tank and MS109 in the dedicated at 55psi. Pulling 9 degrees from the blower tune for the 200.

I've been working up from a 100 shot, plugs were easy to read and looking good at 100 and 150. On the 200 I'm having some concerns.

Fresh plug, startup and spray then immediate turn off. I'm seeing multiple marks on the ground strap, the first pics are before I wiped it clean. Looks like a mark pretty agressive down the bend and another one near the tip. The one near the top becomes more defined after wiping clean. Plus it looks like there is some scorching below the ground strap that has me worried. I'm also torn on the heat range but I'm leaning towards I need to go to a 9. I feel pretty safe on the fuel ring...

Thoughts?

Thanks in advance!!!

 

What jets and is the dedicated fuel system boost referenced?

 

Its a 73 / 39. The standalone is not boost referenced, from my understanding since it is pre-boost (TB plate) it does not need to be.

AFR on the gauge is on the richer side...

 

The porcelain is quite clean for being on the richer side. The timing mark looks pretty safe on the last two plug pictures. The first few pictures it is hard to tell with the coating.

 

I've seen on cars where the wideband read 12:1 and the porcelain be bone white. Do you have a flow tool to set the fuel pressure? Was this pull done on a dyno or at the track?

 

There is a faint color near the bottom that is about 1/8-1/4" thick. Wideband is reading about 11.0 afr.

I did use a flow tool to set the pressure.

This pull was done in Mexico, pulled over and swapped a fresh plug. Startup and hit the spray from 50-150 and shut off the car instantly.

 

First, I would put a 9 heat range plug in it(B9EFS). Then, go up on the fuel a little bit. From there, you will have a better idea as to what it wants. Sort the fueling out first and then move on to tuning the timing.

 

Why such a cold plug Brandon? I didn't see any evidence of excessive heat in his current plug.

 

Look at when he wiped the soot off the strap. Its white and there's heat on the base all around it. I was a little thrown off at first too seeing as the other side of the plug isn't showing as much heat. But, the heat is definitely there around the ground strap. A colder plug is going to give us a better look at what is going on. Based upon his jetting, there should be more fuel on the porcelain as well but as you know, every motor is different. That's why I recommended touching it with a little fuel.

 

Got it. Thanx.

 

I wouldn't consider a 9 too cold. Think about the overall horsepower he's making. Say the blower wasn't there and he was making the same horsepower with only nitrous, he would be on a colder plug than a 9.

 

Agreed, I knew I was border line on the plugs heat range. After spraying the 200 I noticed the heat range was looking a little too hot. The marks are down 3-4 threads on the plug. I was hoping to avoid the 9's for driveability, idle is already pretty bad on the 8's.

Ill try out some 9's this weekend and take some pics and post up the results. I may try adding in some fuel and see what it looks like as well.

Thanks for the info and help!

 

That is a good point Brandon. I had forgotten it was dual power adder.

 

I've tried searching online, but is there a good online article that will further explain how to read a nitrous plug, what I'm looking for timing mark wise (I don't see the "mark" everyone is talking about on the plugs above) and what the various things are to look for? Fuel ring, proper heat range, etc. All I can find is your generic rich/lean reading of plugs (same you'd find on the back of a Haynes manual for example).

I'm looking for something more detailed that is nitrous specific.

Sorry to hi-jack the thread.

 

There's some good stuff out there for reading nitrous plugs, here's a few links that'll give you the basics:

http://www.dragstuff.com/techarticle...-pictures.html
http://rehermorrison.com/tech-talk-8...e-your-engine/

And here's a link to choosing a good nitrous plug with some info in it that's handy for reading plugs. We'll be posting more eventually that'll start going more in depth regarding plugs reading.

http://nitroustech.com/spark-plug-specs/

Let me know if you have any other questions and I'll be more than happy to help you out!

 

Thanks for those Links AJ!

I'm looking for more example pictures on timing marks on the ground strap. I've seen pics others have posted online and I just don't see the marks others are talking about.

I think I have a good idea/seen enough examples of the fuel ring, but the timing mark on the ground strap sill eludes me.

 

Here's a nice example of a timing mark. You can see the color change on the strap. Where that color change happens, is the timing mark. As we add timing, the timing mark will start to make its way towards the base of the strap(around the bend). For reference, this is an NGK R5671a-11. 402 ls. 13:1 compression. C16 in the motor and stand alone. 500 shot with 7 degrees of timing. Could we go forward on the timing? Yes but this is where we felt comfortable leaving it.