What is the gap supposed to be for the plugs on a 99 A8 4.2? Also, what brands / heatranges are recommended (and not recommended)? I tried to search but didn't find what I was looking for...

Just got it yesterday

 

Thats a matter of prefference really. Stock is anywhere from .040-.045. Since these engines have a higher compression ratio i would put it between .032-.035, it should run smoother and be a tad bit more powerful. It will make the plugs wear a wee bit faster though.

 

Wicked! Thank you for the help! Any brands that don't agree with this motor?

 

Crappy ones like autolite. Get a good quality platinum plug from Bosch or NGK.

 

Heard weird things about Bosch not working well in peoples engines... not a problem with us?

 

Those are plugs like the quad spark, with the 4 prong thingys. Electricity only follows the path of least resistance so they tend to fire at one prong on the plug and since they are located in different spots it makes the combustion burn uneven and can cause detonation/poor flame pattern. The bosch plugs you should get for that car are the dual prong, personally i think the NGK plugs are the best possible plugs for that engine and the only ones i would run on that car. Bosch has had problems with the prongs falling off as well, so if you are worried about that go with the NGK's.

 

would it be an issue to use the 3 dollar NGK standard plugs?

 

You mean the copper plugs? They'll work but won't last more than 30k, copper plugs are still widely used by hot rodders and they swear by them, i just don't like changing them out every two years haha.

 

Nice thanks for the help! Yeah I don't mind. I was in a WRX before this, had to change every 10k, but the performance was worth it.


I'll report back how the cheap plugs do!

 

3k miles on em and they're doin great!!