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Spark Plugs. Which ones and why?

26K views 20 replies 12 participants last post by  midnightrun7 
#1 ·
Just seeing what you guys go with. Ive heard NGK(or something to that effect) is one of the best and does bosch or the new E3 live up to the hype
 
#3 ·
^^^Agreed... Stick to what the manufacturer made for the vehicle. Aftermarket plugs/wires will not add any HP that you will notice...
 
#5 ·
A hotter spark can only equal a cleaner burn if the flame front is petering out prematurely. And that would be treating the symptom rather than the cause. Spark plugs are a threshold part - once you cross the threshold of "good enough" all are equal regardless of spec.

If GM is spec'ing spark plugs which don't produce a hot enough spark they are incompetent and nobody should be buying their stuff. I rather strongly suspect that isn't the case.
 
#6 ·
+1

Just stick with factory plugs and wires. Anything else is just asking for trouble.
 
#8 ·
I always used OEM plugs but any good set of aftermarket wires will do fine, from NGK or belden premium wires through napa etc... Fit exactly like OEM and built as good or better for cheaper.... OEM wires are a crazy price and would never touch them
 
#9 ·
gmc2007 said:
I always used OEM plugs but any good set of aftermarket wires will do fine, from NGK or belden premium wires through napa etc... Fit exactly like OEM and built as good or better for cheaper.... OEM wires are a crazy price and would never touch them
Yeah I just priced the wire set... 88.00 for AC Delco from GM parts direct. WOW! A bit cheaper on the plugs, however...
 
#10 ·
TxLTZz71 said:
gmc2007 said:
I always used OEM plugs but any good set of aftermarket wires will do fine, from NGK or belden premium wires through napa etc... Fit exactly like OEM and built as good or better for cheaper.... OEM wires are a crazy price and would never touch them
Yeah I just priced the wire set... 88.00 for AC Delco from GM parts direct. WOW! A bit cheaper on the plugs, however...
That's what I mean, crazy prices... NGK wires are very very well made... I used them on my Pontiac G6 with no trouble, brother used them on his malibu as well.... Lifetime warranty, perfect fit
 
#11 ·
soap said:
A hotter spark can only equal a cleaner burn if the flame front is petering out prematurely. And that would be treating the symptom rather than the cause. Spark plugs are a threshold part - once you cross the threshold of "good enough" all are equal regardless of spec.

If GM is spec'ing spark plugs which don't produce a hot enough spark they are incompetent and nobody should be buying their stuff. I rather strongly suspect that isn't the case.
Not entirely correct. If that was the case, then why tune your engines, or upgrade engine components? A hotter spark can produce a cleaner burn across the board, which produces better fuel efficiency, in combustion engines there is already a lack of combustion efficiency, in modern engines changing airflow rates or compression, or anything done by a tune can also be helped with better coil packs and better plugs.

GM is producing a mandated "standard" engine. Why are there aftermarket parts in the instance where GM is producing a top of the line engine? They produce a good standard, and it's guys like us who take that standard and tweak it. If you upgrade anything in the engine you should tune it. That would prevent a problem in the long run .
 
#12 ·
bombdiver said:
Not entirely correct. If that was the case, then why tune your engines, or upgrade engine components? A hotter spark can produce a cleaner burn across the board, which produces better fuel efficiency, in combustion engines there is already a lack of combustion efficiency, in modern engines changing airflow rates or compression, or anything done by a tune can also be helped with better coil packs and better plugs.

GM is producing a mandated "standard" engine. Why are there aftermarket parts in the instance where GM is producing a top of the line engine? They produce a good standard, and it's guys like us who take that standard and tweak it. If you upgrade anything in the engine you should tune it. That would prevent a problem in the long run .
Your basic point relies on a faulty premise which you can not defend with science. Spark plugs do not burn all of the fuel/air mixture - they ignite the chain reaction. Either the chain reaction starts at the appropriate time or it does not. Once the triggering event happens the burn's "cleanliness" / completeness is a result of the conditions inside of the cylinder - not the heat of the initial ignition source.

Comparing hotter spark plugs to changing the physics of an engine through airflow rates or compression ratio is likewise bunk.

We run hotter spark plugs and more powerful coil packs on our boosted engines not because a hotter longer spark makes fuel burn more efficient but because under the more demanding cylinder conditions inside a higher pressure cylinder it is harder to start the chain reaction. If you have not changed the physics of your engine from stock (and, no, an exhaust or CAI system does not significantly change cylinder conditions) a hotter spark is not needed - ignition and flame front propagation hasn't changed.

The idea that GM would skimp on the ignition system - the idea that they would sacrifice the easiest and least expensive way to improve fuel economy - the very idea that GM would implement very complex cylinder shut down modes - that they would shave grams off of door hinges - that they would spend hundreds of millions developing body panel rolling techniques to give them strength at less weight - the idea they would do all these things to increase fuel economy and the power to weight ratio of their trucks - trucks they sell in a very competitive environment with lots of price pressure - the idea that GM is too stupid to spend $1 more on spark plugs on their stock engines is the most laughable conspiracy theory I have ever heard.

EDIT: Now, if you're running a custom tune and using non-standard timings - clearly you might need hotter spark plugs - but that (again) is a change in the physics of the cylinder. But outside changes of that order spark plugs are a threshold item - either they ignite when you want them to or they do not. So unless you're telling me a stock Chevy misses under WOT when it comes from the factory there is no need to "upgrade" the parts. Placebo is a hell of a drug.
 
#15 ·
AC Delco Iridiums. Why pay more for something that isn't going to give you a huge punch? Save it for a CAI, a nice exhaust, rims and tires.
 
#16 ·
TxLTZz71 said:
gmc2007 said:
I always used OEM plugs but any good set of aftermarket wires will do fine, from NGK or belden premium wires through napa etc... Fit exactly like OEM and built as good or better for cheaper.... OEM wires are a crazy price and would never touch them
Yeah I just priced the wire set... 88.00 for AC Delco from GM parts direct. WOW! A bit cheaper on the plugs, however...
88 dollars!?!?!! i got mine for 65 bucks at oreillys. i didnt get the cheap ones either. then each plug (the good ones were 5 bucks a piece) all ac delcp parts
 
#17 ·
soap said:
Are you or are you not saying that hotter spark plugs on a stock engine can improve engine efficiency?

bombdiver said:
I use denzo iridium, hotter spark = cleaner burn. No HP gain, but better fuel efficiency absolutely.
EDIT: It's getting confusing replying to someone who deletes their posts.
I deleted my post because it's pointless trying to talk to someone who insists on being right, took the time to read through your other posts and once I realized you think you know everything it's not worth the time to try to argue my point. I'll just go with what I know and leave you to preach to everyone and look like an @sshole.
 
#19 ·
This is pretty funny, but informative. What did I DO???????? haha. Do the AC Delcos need gapped? I posted another thread about a gapping discrepency. It says on the original sticker on the fan shroud to gap at 0.040 but in the original manual it says 0.060. Help me out
 
#20 ·
Get the ac delco iridium (gap 0.040) and yes that is the correct gap. I read some where that .060 used to be the right gap but for some reason they changed it to .040. I bought mine about a month ago from rock auto for 4.99 each. Didn't change the wires because the still looked to be in pretty good shape.
 
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