A&Q about 350Z
Q:
My mistake, they weren't really misfiring then
Since you know exactly what I'm talking about....lets hear your theories. Or are you suggesting that they don't have misfire issues?
A:
Sorry Bob, I don't have any theories. In our experience, every major brand plug performs just about as good as it's comparable competitor. However if you want theories....
Spark systems on current engines in the lower combustion ranges typical are FAR more than enough to provide ignition. They currently (no pun intended) can develop open gap voltages over 50K and that's about 3 times what the minimum of what the newer cars require. They run so lean (compared to carbed engines) (and have the higher spark voltages available that they damn near last forever. More plugs are replaced for no good reason than probably any component. Of course, they can fail, but far less frequently than the HV distribution system before the plug. (wires, etc.) (The higher engine compartment temps and higher voltages expose these failures even quicker on than on the older systems)
I am sure that there is some minor statistical numbers that show one plug manufacture is better than some other but across a few hundred, I think you would be hard pressed to see any statistical variation.
Jim
SR Racing
A:
I don't know how extensive your testing is, but I think the "average" engine over extended time is a different story than what you're playing with. That has definitely been my experience.
Again, its quite common knowledge in the circle of mechanics I work with. Those "statistics", if you will, don't come from no where. In my own personal expereince, there is most definitely a significant percentage difference. Very significant.
A:
Up untill a few months ago in class I always thought the Botch +4 were better plugs because of the more grounding areas, thus creating a multi-spark. This isn't the case. What happens is as a plug wears the grounding tip(not sure of the right name) wears down. The problem with the +4's or any other plug like this is that it only grounds to one at a time. The spark goes to the one with least restatance that is why the +4 last longer. There really is no perfromance gains to using these. Personally after the class I took I would just use what ever the car companie used. The way I look at it is, if they are so much better, why dont they come from the factory like that... Hope this makes sense
Akira
A:
many factory plugs are starting to come with multiple grounds. The reason, as you stated, is for longer life...more material to wear.
The reason that the bosch +4 plugs are so popular, is because they are so cheap. Most can be had for under $3 a plug, where as many stock recommended plugs (such as NGK laser plats, for example) are over $20 a plug. So people seak alternatives. I don't know about other stores, but for example, Schucks (a local big chain part store) pushes them in particular.
BTW, I've also seen a lot of damaged catalytic converters due to the +4's, but its all for the same reasons. Misfires.
IMO, doesn't have anything to do with the number of grounds. Its the electrode IMO. The porcelin partially shrouds the very tiny electrode protrusion. I'm too lazy to find a picture of it.
A:
I had the porcelin around the tip of a +4 explode on a car of mine a few months ago. The multiple ground straps caught the pieces before they fell into the chamber though.