I've had Denso IK20 plugs in my 07 TL-S for over 60K miles and love them.
The denso application guide now shows the IK20L as the part for the car.
I researched the spec differences and the Denso IK20L specs show a 1MM greater Projection and a 2.3 MM greater Electrode Height over the IK20 plug. What is the intent of this design difference and are there any advantages realized by it?

 

question...how do you love a certain plug?

 

Your question would be best asked of Denso themselves. They could tell you.

 

Maybe the those Denso plugs never did him wrong like the rest of the women in his life..?

 

If it's been in your butt for over 3 hours in a row...

















What, too far?

 

Sounds like you're speaking from experience maharajamd...

 

You're starting off the flame front from a slightly different place. It's really not going to make a difference in a fuel injected car. In the carbureted days, moving the plugs could mean the difference in getting loaded with raw fuel or not.

Ford with their laser ignition with many points of ignition showed a barely measurable hp gain; the real advantage was in emissions and even that was small. Moving the spark a couple mm just won't do much good or bad. In theory you want the full combustion pressure right as the piston hits top dead center and that's why ignition timing leads the piston to TDC and generally increases with rpm. Some say moving the plug can affect timing (not ignition but actual timing) but again, in practice there's no difference. Unless the spark is shrouded and extending the reach unshrouds it you might see a change but that's not the case for the TL.

 

Thanks IHC.
I was beginning to think the topic was beyond the scope of this site based on the responses to date.
Your response is consistent with what I've been reading elsewhere but with the addition of some real-world insight. I've also read discussion of the extension introducing the characteristcs of a colder plug.
Any experience or insight to that?

 

The heat range has to be hot enough that the plugs don't carbon up but not so hit that they become a source for preignition. There's a lot of wiggle room on fuel injected cars, especially those like the TL that use a wideband 02 sensors and spend little time in open loop. No real performance advantage to hotter or colder as long as the plugs are staying clean and there's no preignition. Obviously if they carbon up and start arcing down between the insulator and body or you get preignition from becoming a hot spot, there's additional performance to be found.

In my turbo car for >26psi of boost I run 3 steps colder than stock to be on the safe side. If I run it easy for a whole day it will start to get an uneasy idle and feel a little sluggish but that's easily cured lol. I've been running one step colder than stock in my TL for about 80,000 miles and they always look great. I do things a little different than most though. Since I like to change plugs and see what's going on in the combustion chambers I change around 40,000 miles, sometimes longer. I run regular copper $2 plugs because I don't need the extended life of the iridiums. The car runs exactly the same and 40-60k seems pretty conservative for regular plugs. Most will say you can only run iridium but there's just no difference unless you're going for those 105k mile intervals.

 

I just replaced my plugs at 108,000 km (67,000 m) and I'm glad I did. They weren't terrible, but definitely had some wear on them. If I had waited until the 105,000 mile servicing, they would have been really bad. I had thought about using Denso, as I liked them (not loved) in my Accord, but ended up going NGK laser iridium.