Are Bosch Platinums the Worst?

[UncleBob]

Originally Posted by SR Racing

Fouling is most often when carbon (or whatever) shorts across the electrode in sufficient amount to eliminate or shroud the spark. In itself, carbon doesn't interfere with the spark since it is a great conductor of current. Of course, a carbon deposit can get hot and cause pre-ignition, but this is more of a problem with standard plugs.

In regards to the resistance build-up on plugs at the screw on cap... Old wife's (mechanics?) tale.

The resistance at that point (of even several thousand ohms) has zero effect. It is at ambient pressures at that point and the resistance MIGHT drop 500 to 1000 volts at WORST. Whereas the avalanch voltage is in the 40K range. You would literally have to have a .010 to .020 inch air gap. (at normal pressures). Try this on your distributor tester.

In any case, the caps are not torqued so that the installer can remove them when installing on those few cars where they are not used. We tighten them up, but it ain't an issue.

Jim
SR Racing

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?

[SR Racing]

Originally Posted by UncleBob

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?

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

[UncleBob]

Originally Posted by SR Racing

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

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.

[Akira13126]

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

[UncleBob]

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.

[TheSilentChamber]

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.