I know the spark plug question has been beat to death, but this is a little different.

My T/A has Denso IT16 Iridium spark plugs installed (previous owner) and I was curious if these are a bad plug to run for this car. From all the posts I have read, it seems that everyone shys away from all the fancy plugs w/ forced induction. The Denso's have been in the car for at least 3,000 miles (how long i've owned it) and seem to work fine.

I pulled a plug to see how they were holding up:
- the metal body surrounding the ceramic tower is black
-the ceramic portion is dark tan
-the electrode has sections that are black as well (I will post up a pic soon)

Second question not related to the Denso plug; does anyone cut back their electrode? I have read that this simple mod can net substantial HP in FI cars?

Thanks in advance,
John

 

Those plugs seem to work well. A lot of the import turbo guys use them. They are like $6 a pop.

 

Good deal. I wanted to ensure that I wasn't opening myself up to problems down the road because of a poor choice in plugs. Do you forsee complications with using nitrous and FI on these plugs? I have sprayed a few times with no problems thus far, but I like to error on the side of conservecy.

 

from what I have hurd these plugs are like the MSD box for spark plugs if you catch my drift. I have not read much into it as for advantages but I would assume better spark to the electrode as rpm increase, probably allowing a bigger gap. Someone else may be able to give more info. Im not much for spending 6-8 per plug so never looked into it.

 

Something to watch for is heat retention of the plug, leading to pre-detonation. Platimiun plugs don't disipate heat as well as copper plugs. I can't comment on iridium plugs for heat disipation.

Spark plugs gaps are reduced for SC cars (usually .035" - .040")to prevent the spark from being "blown out" due to the increase in air flow. An aftermarket ignition box/coil generates a hotter spark to also help.

 

This gets more interesting by the minute. The Crane HI-6 kit that was supplied w/ the Vortec unit is installed, so spark intensity shouldn't be an issue. I'll measure the gap tonight to see where it was set at. Additionally, the car is pushing 6 lbs of boost at 4,500 feet above sea level, which is odd for a factory set-up (this should only generate 4 lbs at this altitude....if it has a stock pulley).

What is the difference between pre-detonation and detonation?

VR,
John

 

There is no such thing as pre-detonation.

There is a thing called detonation, and there is a thing called pre-ignition.

 

Iridium will transmit the heat away faster than platinum, but not as quickly as copper will. It will be more prone to hotspotting due to the design of the plug.

I would stick with a copper plug in a FI application, though the Ir plugs are a better choice than Pt.


Chris

 

Pre-ignition is the proper term. Detonation is supposed to occur when your spark plug fires, not before. If you have a hot spot, your air/fuel mixture can fire prematurely (pre-ignition), cause the engine to knock and cause damage.

 

So the copper plug is the way to go. Understood.

Now, has anyone cut back the ground electrode to where it only covers part of the center electrode? A recent magazine article used this procedure to net some additional power out of a forced induction motor. Just curious if anyone has put this into practice.