Just found these plugs, they list a part number for the SHO which is good. The Iridium TT are the ones im interested in. What are your general observations and opinion on these plugs? Think I should try them?

http://densott.com/

Part# ITV20TT


Edit: I ordered some... I'll have them in tomorrow night. so we shall see.. or I will see. Seems awfully quiet in here.. lol.

I use the ITV22...just a step cooler.  Absolutely no problems with 15k miles on them so far

Denso ITV20TT and Autolite XP5363 is comparable to OEM/Motorcraft SP534 in terms of heat range.

Denso ITV22 and NGK 6510-LTR7IX-11 are a step colder than those options.

Based on this post, some addn'l comparative data:

NGK-LTR7IX-11 Reach: 25mm (.984")
NGK-LFR7AIX Reach: 26.5mm (1.04")
Autolite XP5364 Reach: 17.98mm (0.708")


NGK Spark Plugs Heat Rating

The spark plug heat range has no relationship to the electrical energy transferred through the spark plug. The heat range of a spark plug is the range in which the plug works well thermally.  The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type. 

Heat rating and heat flow path of NGK Spark Plugs

Heat Rating and Heat Flow Path

Some basic structural factors affecting the heat range of a spark plug are:

- Surface area and/or length of the insulator nose
- Thermal conductivity of the insulator, center electrode, etc.
- Structure of the center electrode such as a copper core, etc.
- Relative position of the insulator tip to the end of the shell (projection)

The major structural difference affecting the heat rating is the length of the insulator nose.  A hot type spark plug has a longer insulator nose.  The insulator nose of a hotter spark plug has a longer distance between the firing tip of the insulator, and the point where insulator meets the metal shell.  Therefore, the path for the dissipation of heat from the insulator nose to the cylinder head is longer and the firing end stays hotter.  The insulator nose of a hotter spark plug also has a greater surface area that is exposed to more of the ignited gases and is easily heated to higher temperatures.  A colder spark plug functions in an opposite manner.

The heat range must be carefully selected for proper spark plug thermal performance.  If the heat range is not optimal, then serious trouble can be the result.  The optimal firing end temperature is approximately between 500°C (932°F) and 800°C (1472°F).  The two most common causes of spark plug problems are carbon fouling (< 450°C) and overheating (> 800°C).   

Thanks for the info. I was just about to read into that. I called denso and the tech said they do not offer a colder range in the Iridium TT for the SHO as of now since it's  new.

Since my 534's are doing OK I think the heat range will work. It will be interesting to see how these new plugs perform. They are supposed to have the performace of their race plugs but the life of the Iridium plugs.

I'll have them in tonight and I'll do a few test runs.

Cool!  Looking forward to results ...

I'm happy with the new Denso Iridium TT plugs. Did a few runs and my usual knock of 1.5 was no longer being registered.

Old plugs were gapped at .030 new ones are at .028.

Since I do not have a dyno in my back yard I cannot give any factual data on power increase or efficiency increase. But I can say the car feels a lot more sensitive at low rpm. I noticed when leaving stop lights the car pulls more aggressively. That is my opinion though.

I'll check back in 1000 miles and see how they are doing.

Here's a question... Not just what plug, but how often do folks check their spark gaps and plug cleanliness? .... and what are you finding at these mileage intervals?

Put these Sp534's in when I tuned the car...12k on em. Gaps were still .030

Rich

I checked mine at 16k miles and they looked good but this was before tuned. I put new ones in at 23k (now). The plugs still retained the set gap although the insulator looked "cooked".

Let's see if this is the plug that goes the distance