This might be somewhere already but I couldnt find it:

Why is the recommended spark plugs for the type S the NGK IFR6K-11 and the recommended plugs for the 3rd gen 3.2 IFR5K-11? And is it okay to put the 6K in the base car?

The 6K is what they had in stock, the others were not available. When they say that the 6 is a step colder than the 5 what does that mean?

And if you modify the car for more power is it better to run the colder plugs? Im assuming there wont be a noticeable difference, but I want to know why Acura recommends certain plugs for certain engines.

 

Wrong. The recommended plug for the 3G 3.2 is the same : NGK IZFR6K-11 (6994).

BTW, you left out a "Z".....

 

Okay, I got bad info then. In my Haynes manual it says IZFR5K-11. I guess its a mistake or typo. My car didnt come with a manual and I didnt check online. So then I did get the correct plugs. Still interested in what difference running a step or two colder would do.

The 3rd gen 3.2 and 3.5 use the same plugs then?

Ive read that people who add turbochargers will go with a plug two steps colder to reduce knock, but on an NA engine would it have a noticeable impact? So would running the 5K plugs cause unwanted detonation?

 

Stick with the stock plug heat range.

 

I didnt ask that.

 

The stock range is the best. This is more or less how hot the plug itself and primarily the middle electrode will run. If the plug itself becomes a source of detonation then a cooler plug will help. It's extremely unlikely at any modification level in a naturally aspirated 3G that the plugs will be a source of detonation. Driving style is a more likely influence than mod level.


Mine had light detonation when it was brand new. I couldn't hear it but it showed up on a scanner. I went with one heat range colder just to try it and it made no difference whatsoever. I ran the car a few times on the road course with lots of time at full throttle so I just left them in there.


Too cold will cause fouling of the plug. Too hot will cause detonation. Stock is a good compromise and with the colder plugs, they were still in like-new condition when I replaced them, no excessive carbon on the insulation. You have to think that the vast majority of TL owners use them as basic transportation and they get driven easy so the stock plugs are chosen because they're not likely to foul with very easy driving.


You can go a step colder and likely see no downsides but it's extremely unlikely to have a positive effect either. For what it's worth I don't use iridium plugs or even platinum most of the time. I use regular $1-$2 plugs because I change every 40,000 miles. I like to see what's going on inside the combustion chamber and I don't like to leave plugs in an aluminum headed engine for 100,000+ miles. The biggest and arguably the only benefit of iridium (besides an unproven unshrouding of the spark) is lifespan and not performance. I never had luck with iridium or platinum in high boost turbocharged vehicles. I had to go too cold to keep it from detonating.


On the extreme end of the cold plugs, I was running 3 steps colder than stock on my turbo car which was factory turbocharged so they were very cold plugs. This was only for the track or hard street runs with boost in excess of 30psi. When I got lazy and didn't change them out when I was just using it for driving to work, after about 2 days of easy driving it would get a slight misfire. When I pulled the plugs, they were fouled. The easy fix was one or two full throttle blasts and they were fine again. Once I got used to them I would just step on the gas at the fist sign of misfire and I was usually good for a day or two. One step colder in a TL won't have that problem.


If the Type S really did call for a colder plug or if it was chosen at a later date it's probably because the S is more likely to be driven aggressively and the stock plugs probably lean toward the hot side because it's easier to deal with a little detonation than it is with fouled plugs from a factory perspective.

 

NGK Spark Plugs USA

Above is a link to NGK that addresses your question.

 

Thanks guys for your input and the link to a wealth of knowledge. That was what I was seeking. I already bought the stock plugs. I was just trying to learn more.