: Bosch +2 plugs (report)

07-18-06, 07:28 AM
Well my 2001 eldo has 47k miles on it now. And I've always been a fan of the bosch +2 plugs. So I figured I'd put a set in and report what I found.

My stock plugs were a denso brand. They looked nearly perfect. However the gaps were a bit inconsistant. Only thing I can say about thier performance was that idle seemed to be a bit rough when I first got the car at 38k miles. I'm guessing it was more likely the injectors being a bit dirty than the plugs?

Anyway.. so this weekend I put the bosch +2 plugs in. They have a sideways spark which does not shield the flame front as it propigates away from the plug tip. Every motor I've installed these in have shown the same thing. Better idle and more tip-in punch. A couple cars even had a bit better power up top.

This eldo with it's NS did'nt show much improvement. Idle is about the same, tip-in and low rpm power seems slightly better, milage is the same, and WOT is no different.

So in summary I'd say it was not worth the effort. The stock plugs were in excellent shape and SOTP performance was the same. I'm still a fan of this plug and will continue to use them. But I'd have to say that on my NS there really is nothing to be gained from them.


07-18-06, 12:54 PM
Some folks report problems when they change to non-OEM plugs. Glad yours were not problematic.

07-19-06, 02:11 PM
I think it really comes down to two areas when changing plugs. 1) The flame fronts propigation. 2)The component quality and plug resistance.

I do use the Denso IT-20 & 22 on my lightning with perfect results. (100 shot of nitrous on top of 14psi) It's a proven plug in that environment and has a ultra smooth idle. I spoke to a Bosch engineer about using the +2's and he said I should'nt yet because they have not been tested in a S/C w/nitrous application.

Having driven the car a couple hundred miles now I'd say there is a noticable increased punch when at lower rpms and heavy throttle. Like.. at about 2000 rpms and you go 50% throttle. I find the tires barking a bit where as it used to not do that. I donno... it's a subject thing I suppose.

Just figured I'd report what I experienced. Mostly because I remember posts saying anything other than OEM plugs were inferior.


08-08-06, 03:12 PM
I was using the plus 4's in a previous car and noticed a big change in that previous car.

Well I upgraded the N* to the +4's and I've noticed that I now have quicker starting. It seems to run a little stronger as far as climbing hills and sort. It also idles smoother, and is getting better fuel mileage around town. I was told that the computer regulates how much spark the plug puts out, so not to worry if it would burn too hot, but I would recommend these if anyone hasn't had any long term problem from them. Just putting that out there.