Ever see caps on trailing spark plugs?
 

I saw this when I tore my engine apart. I am wondering if anyone knows of why this would be done. It was a cap right over the end of the plug.

pic?

bump, I will post pic soon.

you saw what? :confused: ... this thread fails without pictures :Wconfused


let me pull out my crystal ball and take a look

Did they look like tiny aluminum hats with a tip that would seal up the hole in the rotor housing? If so, that's the "anti-detonation device" that was sold by Skip from KD Rotary. He noticed that if you disabled the trailing plugs you can run higher boost than normal with reduced detonation. These tiny little hats were his way to disable the trailing plugs and try to keep the modification a mystery. You can search on here for "anti-det" and probably find out more info...

Thanks for the above info. Here are the pics.

Yep, I recognize that. It's the infamous "anti-det. device" that appears to be stuck or something to the plugs. IDK, maybe someone saw those in person a while back and made something similar and somehw stuck them on a set of plugs, or they are the ones he (Skip) put in.

So tell me more about these anti-det. caps. Do they work? Are they useful on low boost or are they for race applications only? do they cause fuel consumption to increase?

The "device" is really the same thing as not running your trailing plugs. The only reason there was a "device" was to turn the idea of leading only ignition into a $500 product.

Trailing plugs extract a bit more power and clean up emissions a bit. Running no trailing seems to allow you to squeeze in more boost than you would otherwise be able to (before you experience detonation/pre-ignition.) I imagine it does this by eliminating the second flame front and slowing overall combustion, effectively lowering combustion temps and peak pressure.

So the question remains.. do you get more power from a properly operating trailing ignition or from squeezing in more charge with less efficient combustion. I'm not sure this was ever answered.

..dave

yes they were the original caps used for the anti det devise. anti det was these plugs, and a few clipped wires on the trailing coils.. eventually skip had real nice machined plugs that screwed into the plug holes i have them on my car. i'll get you guys some pics tomorrow.. i also have a few of these caps laying around to