i put a set in my trailblazer and it would not run. when it finally fired off it sounded like something was inside the cylinder banging and clanking. i took them out and returned them immediatly...

 

I'd NEVER use 'em in a vehicle I cared about !!

I've seen the +2's and +4's cause all kinds of engine problems.....everything from uncontrollable detonation to the plugs falling apart in the cylinder, to being unable to start the vehicle

 

A shop around here got to the point where they would ask if they were using Bosch plugs when someone would call about having engine trouble. They said they would replace the plugs and all would be fine.

 

so it seems like these are well regarded...........

 

When EVERY response to them is negative (and coming from a group of people with a combined knowledge of these engines that is utterly amazing) I'd have to say I'd skip them as a mod....

actually...on second though, RUN 'EM !!!...it *may* just make me faster than you

 

I've used them in a (don't laugh) Honda 1.5L with good results for 45K miles. Never used them in anything else. A friend used them in a circle track (non GM) race truck with good results. Maybe it's a GM thing....?

 

I sold autoparts for 4 years and have used bosch platinums personally and have seen all the returns. My opinion....Bosch Platinums=JUNK
I would put a $.99 Autolite in an engine before I would ever take $50 to install a set of Bosch Platinums.

 

well damn, guess im in need of some NGKs. Dont make fun of me.

 

I am convinced after personal expericne with them it all comes down to the design of the combustion chamber. I ran +4's before i knew better in my OBS 2000 Denali, (vortec 350) with decient results, it idled nicer but thats about it.

Also had them on my current denali for about 1000 miles nad returned em. Just caused some odd harmonics in the engine espeically between idle and crusing transitions.

So with this in mind its gotta be something to do with all the variables that makes up GM's GenIII/IV heads. Wedge design, angled plug. Vs. others such as the GenI heads which used a perpendicular plug (to the axis of the crank), but was also a wedge design. DOHC engines which seem to have good results with them, their plugs are inline with the axis of the piston travel, and with the 4v heads their combustion chambers are shaped vastly differently.


No i really have no numbers or anything to prove it. But it seems to make sense to me.

 

I think it has something to do with those things you mentioned about the newer sb GM engines. I don't think it's a bad plug in other applications.

The Honda runs well with them as well as a friend's somewhat-modified 318 in a circle track racer. It has about 310 fwhp and runs at around 6,000 rpm most of the time.