C5Natie

Hey guys, been wondering what's the best spark plug for my cam only LS3? I just picked up some ngk tr6's, they're gapped at .0037-.0038 out the box. I would like to stick to a copper plug. What do you guys recommend? Car is making 470/460 to the wheels. Thanks.

C6RaceCar

Ls7/ls9 deco plugs. Forget the copper.

C5Natie

What are those, iridium? I know copper doesn't last as long but usually gives a stronger spark. Is that still true in this case?

C5Natie

Btw, are the LS7/LS9 a colder heat range then stock LS3 plugs?

schizcat

Yes. And they are iridium.

lt1z

Any 6 heat range plug will be fine for that power level N/A. The delco plug is actually a denso plug equivalent to the It-20 or tr6ix.

C5Natie

I know iridium plugs last longer but do not perform as well as copper. Thats just a fact. So is anyone out there running a copper plug in their LS3. Copper vs iridium, $2 vs $13 each for no gain is tough to swallow and I dont mind changing my plugs every 20-30k mi. Its a 10min job.

j_digi454

Before you decide, look at post #50 of the attached thread which states that the Vette ignition was designed for iridium plugs and that copper can, not always, activate the "Check Charging System" message on your DIC. I had that problem with NGK TR6's and changed to the LS9 plugs which solved the problem.

http://forums.corvetteforum.com/c6-t...ls2-3-why.html

I bought my plugs on Amazon for $7 ea. plus a $2 rebate per plug if price is a concern.

C5Natie

Gonna read that thread and look into that. Thanks. Ive always ran copper autolite plugs with no issues and still have the LS1/6 ignition system with this motor. Price is not an issue, just why pay more for something that wont perform better. But if it did give me problems like you saw, then I wouldnt mind paying for whatever works best.

C6RaceCar

Same here. But with the C6 for some reason, it just dont like them. But yes the TR6 plug is used by everyone with little to no issues. Just with this car, you are better off with the iridium.

C5Natie

Well I had the tr6's so I threw them on. I did a wot with them and then inspected them. What I went off off was the color band you can see on the ground strap. With the stock heat range they were close to the base, indicating it was on the hot side. With the ngk tr6's, the mark is now closer to the middle of the strap indicating a proper heat range. I noticed the car idles very well with the ngk's and seems to rev up smoother. Also less exhaust popping on decel. Only thing now is, I did a 3rd gear wot test on the fwy today while data logging.I figured it was warm and if I would see any detonation it would be then. I got no knock and the car felt great BUT the timing at wot was 31.9* when I had tuned it at 28*. Im guessing the ecu sees no knock and is advancing the timing? Iat' were low, 90's*, but I have that table tuned out anyway. No ignition or charging system dtc's either.

Neumonic2002

Not sure how much overlap your cam has but I never got more than 4K miles out of a set of TR 6's. don't believe they are copper either, NGK tech told me the iridium plugs were better for performance than the TR series plugs anyway.

C5Natie

Theyre copper with a nickel coating for corrosion, at least thats what NGK says. I drove the car around town and to work, maybe 80mi. They looked fine to me and Im sure they would say to go with iridium, they cost more. If any plug doesnt last 4mi, somethings wrong and its probably not the plug itself unless its a REALLY wrong heat range or gap. Ive never seen a plug crap out that fast due to the metal its made from. I still have the LS1 ignition system but I doubt the LS3 system would be that sensitive. Who knows..

raspyc6

I traded out OEM plugs for NGK TR6's @ 37gap

C5Natie

How do you like them?

Neumonic2002

Sorry, corrected my post....meant to say 4,000 miles.

If I can find the tech article I will post the info here, I have posted it already this year in a different spark plug thread. I'm not knocking the TR6 plug, it works well when you are above 11.1 compression ratio no doubt. Frequent changes don't bother me either.