What's the best spark plug for 2008 base LS3 Auto? thanks ss454

 

For your car, if you're just stock NGK TR5IX

 

Use NGK and you will be happy.

 

As someone who chased a random misfire problem after a plug change in a GM non vette I won't stray from AC Delco anymore.

 

I've been using the stock AC Delco plugs in my '08. Apparently, they work good enough to run 10's in the quarter with just bolt-ons.

 

NGK tr5 and tr6 are ok but don't last long one thing GM got rite is their spark plug choice AC Delco P# 41-104

 

Yeah, tr5 or 6 is the old school copper plug. I tried TR5s when I was stock and found the gap was widened a lot after a surprisingly short time. Too short.

With little info, and assuming the OP just wanted to do some PM, the 5IX is a stock replacement iridium.

One thing about the stock factory iridiums, even on a stock motor, when I pulled them at 45K miles, I found two out of 8 with the iridium tip completely missing. Gap was .080" on those two. I had to do a double take until I realized the tips were missing. Others have said the same. LS3s seem to like to eat those.

I use TR6s now on a supercharged application. I might try the TR6IX on a replacement.

 

I agree about the iridium tips coming off. I haven't found what causes that either. I never checked my originals when I changed plugs at 72K, so no help there. Somewhere around 115K, I noticed a backfire a couple times just as I went WOT from around 2K RPM. I later assumed that was a tip coming off. Then on a trip to Sacramento to go racing, it backfired a couple times while running normal highway speeds. When I got to the track, is when the results on the timeslips showed up. Strangely, it wasn't consistent. I sometimes got a fairly good launch, but it would fall on it's face in 3rd gear. Other times, the launch was crap, but the rest of the pass was fine. I was scanning every run and saw no pattern. Even though I managed a PB of 10.80, I never put together a clean launch with no high end problems. The spark plug problem never occurred to me at the time. I was thinking intermittent voltage issues.
After getting back to Phoenix with no further problems, I finally pulled a plug and saw a missing tip. Then pulled the rest and had 7 of 8 missing. Put in a new set and went to the local track and easily had better 60' times, but with higher DA, the MPH wasn't there.

I guess the bottom line is that the car will run fine with .080 gapped plugs if you never go WOT.
It does bother me about the tip floating around until it finds it's way out or becomes embedded in the head or piston.

 

Anybody tried running E3s? Just curious.

 

God at 115 K you got your moneys worth I guess unless the tips fall off these plugs burn and feel very crisp unlike the NGK TRs which seems like you know you need to change them every few k miles or when headed to the dyno.

 

I think you mis-read the plug changes. The first change was at 72K. Then around 115K was apparently when the second set started to fail. They were changed about 120K.
Around 142K, I checked the plugs again and found 1 of 8 had the tip missing, so now I'm on the 4th set.
I recently backed off the timing a degree in the 5200-5600 range to see if that was causing KR at WOT when I was using 91 octane or if I'm running too lean then. I won't race again until late Fall to check that out, but yes, I'll be pulling and checking plugs far more often now.

BTW, I haven't been on a dyno to tune since 2009. All subsequent tuning changes have been made according to scans and timeslip results.

 

Plug wires can also be a cause in diagnosing less then perfect performance .... Replaced mine at 67k miles and it was a clear night and day difference in efficiency and performance ...much stronger low to mid range... The wires themselves looked in ok shape... Just goes to show you never underestimate the smaller things!

100k miles lifespan my ***!!!

 

My car is approaching 140K and it's on my third set of wires. If anything I let them go a little long. It should probably be on its fifth set.

The wires degrade in the underhood heat and start misfiring. If I tried to make it to 100K the car would be running like a Briggs & Stratton.

At every wire change, the plugs looked okay. Changed them too, of course.

 

Do either of you guys drag race and/or scan your WOT runs with a device that records engine performance through the OBDII port? If not, what's your method to determine if the wires are bad?

 

Usually I'll notice a miss at idle and a stumble on takeoff that comes on when the engine is hot.

You can watch misfires in the live data on a Tech 2. The car can accrue them at quite a rate without ever throwing a code.

In my case cylinder #4 was showing the most misfires. And sure enough, the silicone insulation on the #4 wire was so cooked that it broke clean in half at the elbow with only a slight pull.

(It's pretty normal for the wires to break, but I usually have to pull harder, and they tend to fail at the plug terminal).