Best NGK spark plugs for H&C LS7?
 

I have a 2006 ZO6 with built LS7 Earl short block 12:1 compression with milled stage 3 heads and cam in the 230/240 duration range at .050" lift. Power is in the 550 - 570rwhp range.

When I bought the car it had NGK iridium TR7IX spark plugs and after adding high flow cats I had it retuned and my tuner said it slightly detonating at higher rpms.

We pulled the plugs and they re-gapped down to .032" and got the same result so we scrapped them for a new set of NGK BR7EF that came pre-gapped at .032". Runs good now but wondering if this plug is too cold at 2 heat ranges cooler.

Curious what everyone else is running with similar mods and what experience you have had with different plugs and gaps.

:cheers:

Spark plugs
 

The 7IX is one step colder than stock. I think I run something similar to the 7IX. Keep us posted on that I guess my one concern is it (the one you chose now) too cold a plug for pooping around town.

I run NGK TR7ix, on my HCI. I also have flex fuel, and run e25 at a minimum, and more like e35-45 as a norm.

Just check the plug threads, and see if they are discolored and clean for 2-3 threads. That'll tell you if your heat range is right for the type of driving you do.

stock is a 55 range.

TR6 is what I am running at 550whp with no issues with a similar build. I would think TR7 would be way cold at your power. I wouldnt go to them unless I was in the 625-650+ range.

And from all the research I did, skip all the fancy iridium and what not plugs and just get the normal ol TR6 copper plug(its nickle plated, but a normal copper plug otherwise) for 2 bucks a piece and change em every 10k.

Stock LS7 plugs are an NGK 6 heat range. Same goes for the LS9. TR7IX have been proven in H/C LS7 combos. With that said, I have been successfully using TR6 plugs in my 600rwhp setup, but may switch to a 7 heat range with the new motor. Some get charging system issues when using the fatter electrode plugs, like the TR6 and BR7, but I never have.

The BR isn't a projected tip, like the TR is, so that can change things as well...it is more than just a heat range change when going from a TR6 to a BR7. Ideally, you'd stick with a projected tip at your power level, but if the BR plugs are working, I'd leave them be. They won't hurt anything.

You sure about that Brad? I could of sworn stock heat range was 55's. Hell, maybe I'm running to hot a plug then with the I7x. I've had to pull a shitload of spark. ...

I just finished a friend's Z06. 580'ish, 11.5:1. He has TR7's installed. Prettiest spark tables I've seen. No kr at 29 deg. No power gain with that much, so I left it at 26.

I use the NGK BR7EF plug on H/C. Been working great.

I tried tr6ix at 0.040 last week in my H/C car and they ran like ****. car bucked like it never has before at low rpm- and it was fat at WOT. went back to stock plugs at 0.040

im pretty sure 55's are factory. At least thats what I pulled out of my factory heads on a car that was 100% dealer maintained.

on the regular TR6(copper plug) .040 is to big. 032 is the recommended for the standard TR6. Is the iridium plug able to bridge the gap better? Sounds like not.

correct.

Yeah, I'm sure.

Factory plugs are ACDelco 41-104 Iridiums (pretty sure it's a rebadged Denso), in the LS7 and LS9. The 104 cross references to an NGK 6 heat range.

The LS3 uses a 41-110, which crosses to an NGK 5 heat range. That is probably where the confusion came in.

That 7 should be plenty cold for your N/A setup. My buddy runs the TR7IX in his 800rwhp ZR1. I've seen some claim that the IX plugs acted differently than the fatter wire. TR7s are cheap enough that you could just try them and see what happens.

which part is correct? The gaps? Or that the iridium supposedly can jump the gap better hence the wider gap(although in the other posters case, maybe not)?

So I should maybe try them at 0.032?

im not saying that, although IMO it wouldnt hurt anything to try them there. Whats the worst that happens? The car STILL runs like ****!

What I said was the plain copper plug(TR6) gap is 032. I dont know what the iridium(TR6IX) gap is supposed to be. 040 might be correct for that plug. I would wait for somebody else to chime in on the proper gap for the IX-iridium plug.

I personally feel that the non-iridium i.e. standard copper plugs are slightly "better" as far as ignition goes, but they just dont last nearly as long as iridium. I plan to change mine every 10k miles where as an iridium plug supposedly is a 100k mile plug.

One other consideration, I ran 97mph in the 1/8 and 128mph in the 1/4 with the NGK TR7IX and half a tank of gas and a few weeks later ran 96mph in the 1/8 and only 124mph in the 1/4 with the NGK BR7EF with a full tank of gas.

I've been trying to find proper plugs and gaps for my set-up.
LS2,243 heads,cam and all bolt ons 494whp on E85 (flex set-up). Any advise is appreciated

OK update pulled the NGK BR7EF plugs out gapped at .028" and replaced with NGK TR6s gapped at .039" and engine woke up big time much smoother and peppier feels like a different engine. Thanks to all for your responses.

:thumbs: :rock:

that's good to know and shores up my decision to retain stock heat range plugs as I am still stock CR but with a bigger cam and 280cc heads

And never use anti seize on the threads?