What's my plug range?
 

Engine info
LS7
compression between 11.7-12:1
Pump gas 93 octane
2000 miles on plugs
600whp

TR7IX gapped at .035" with a few thousand miles on them.

Looking at the ground strap, is it too hot or is it ok for my application?

Plug Read
 

Hi Wolf, I use the ground strap "read" more for AFR which looks good.

The Heat Range is better read on the White of the plug, please post a picture if possible ?
There should be a "fire band" mark 1/2 of the of that length.

I do see some Black on the insulator "specs" OR just a poor picture ?

Lance

You can zoom into the picture if you click it. The definition shows some specs yes.

What do you mean "white of the plug" and "fire band mark"? can you explain? thanks!

The white of the plug is the insulator; I THINK what he means by the fire band is the discoloration of the lower section of that insulator.
Lance? Did I call this right?

I looked through lance's post history to see if I could find Pantera pictures, but what I found was WAY cooler! LOL

I will take some more pics if I am able to.

I think ORIGINALLY he made parts for DeTomaso Panteras (just a guess) , has expanded his horizons a BUNCH. If anyone has been there, done that, it is him.

It was SO HARD to get these pictures. If anyone needs their spark plugs photographed, send them in to me. I am now a professional.

Spark plugs to me anyways seems to be a very interesting area as the die hard engine/race shops rely more heavily on plug readings than actually reading AFR gauges and what not.

A good rule of thumb: use one heat range colder for every 75–100hp added. Heat ranges vary from different plug makers. Maybe a NGK TR5 over the 7? I know they say for max performance a colder plug but if mostly 90% street driving a standard heat range.

Maybe run a wider gap .045-.050

Fine Wire Sparkplug Use
 

Hi ALL, the pictures show a fire-band OR shadow, not too sure.
There is much material on the ground strap ?

These ARE fine wire Spark Plugs good for a single Coil per plug application.

SO I ASK the EXPERTS : Why is a fine wire plug BAD for a TWIN Post Coil ?

Winner with correct answer will get a free set of E-3 Spark Plugs.

Lance

Taking a stab here, but does it have to do with the difference in OHM's produced from a twin post coil?

Twin Plug Spark Plug Heads
 

Hi, thanks though this is not the case.

Lance

Why are you suggesting such a wide gap? Factory suggests .040. I gapped them down due to colder heat range

My application is single coil per plug. That's why I used the iridium plugs. What else could you say to me about how it looks? What gap would you use? Thanks.

Most spark plugs in late model vehicles have wide gaps .045 to .055˝ to promote reliable ignition and better burn off. I think a wide gap would help with carbon burn off but don't quote me on that.

Many circle track and drag cars run plugs with narrower gaps in the .020 to .035˝ range to reduce misfires. Some Pro Mod motors run gaps of only .014˝. Top Fuel dragsters and funny cars may run spark gaps as narrow as .010 to .013˝ because of the extreme conditions inside those combustion chambers. But all these guys run right up to the edge for extended periods where street guys mix in a lot of cruising, idling, and start-stops.

I've read that spark plug manufacturer say a good way to determine the ideal plug gap for an engine is to start out with a modest gap of around .035˝and gradually increase the gap until the engine starts to misfire and lose power. At that point you should reduce the gap several thousandths to achieve the best possible gap. But that sounds like a ton of pain in the ass work especially on f-bodys.

But from seeing others the NGK BR7/TR7 Spark Plugs are the most popular for high horse N/A and Nitrous setups so I think you're good in that area. But gap wise I'd imagine opinions will vary but as stated could play around with gaps.

Few things:

• This is a C6 Z.
• This is a Street & Road Race car.
• The cam is big (236/250/113+2).
• This is a 93 pump gas only car.
• I usually do a WOT pull once per drive.
• Although it is a forged rotating assembly, I'd rather be on the safe side rather than detonate in the higher RPM range. I don't trust the OEM ignition system for a C6 Z

Arc Duration
 

Hi Wolf, the energy in the coil should be spent for about 30* of crankshaft rotation inside the cylinder.
That "read" is called the Firing Line, an EASY read with scope use.
Most here state the wire resistance, plug gap, etc. effects this ARC DURATION.

When a plug has a SMALL GAP, the Arc Duration could be longer than that period WASTING Current.

As STATED, use the widest gap, max coil dwell, good coils AND you will have best engine performance in most cases.

A wider Plug Gap will require LESS Spark Advance as does a stronger spark, higher in Mj energy content.

Lance

Lance,

What are some symptoms of too small plug gap/wasted current?

Thanks

Arc Duration
 

I Wolf, the Spark instant, more advanced timing required, AND less HP.

Lance

Thank you. I guess my main question is do you think I need to go to a hotter heat range, or just stay with 7s and widen the gap? Thanks!

Heat Range
 

Hi Wolf, the posted pictures show the heat Range is correct.

Lance