what would be the difference in 'performance' of the iridium ngk plugs compared with the 'standard' ones, at same thermal grade level? i pay here the standards 4 usd/each, these ones cost 16 usd each

is this difference in price justified?

 

Not worth the difference. You certainly will not notice it. Iridium is supposed to be a superior conductor and they are also supposed to last longer. We put a set in my wife's Grand Prix GTP and noticed no difference in performance. The only difference was a lighter wallet. You can't go wrong with the AC plug for your application or the standard NGK which is an excellent plug.

 

I put a set in my F-150, no noticeable difference in performance

 

i supposed so...i've got 8 ngk BCPR5ES plugs ready to fix following my engine guilder advice...but, is the thermal grade here cool enough? it seems to me a little too warm for my application...thanks/Giu

 

I would go with your engine builder's advice. I always run the warmer heat range. To me it seems to burn better and provides better throttle response than a colder plug.

 

We changed a 2-stroke race bike over to Iridium plugs and went from changing plugs nightly to not changing at all. I know this is an extreme case as 2-strokes are prone to fouling but if you are running a hot rod motor thats extremely rich at idle they might solve plug problems. Oh, with the race bike we never saw an increase in performance, just a decrease in plug maintenance.

 

Same experience here (2-strokes). With a "racing plug" I was able to set the oil pump to max and didn't foul the plug.....

Didn't notice any difference when using these fancy plugs in my car. For my DD I just got the Bosh 4 prong platinum BS plugs for $7 each and there's no improvement over the standard $2.20 NGK plugs that were in there for 70K miles....

 

good point, on 2 strokes race engines you can't avoid using them, i used to have an aprilia 250cc race replica and would 'consume' plugs like hell
i believe the point is that iridium reduce plug maintenance (like in subaru's/and other ricers where you'll have the first change after over 100.000 kms!)..i've started this thread because a parts supplier, who knows my car, told me to use the 'new' iridium ngk instead the usual ones as they'd increase performance by far...so i thought there was something i had missed abt new plugs...thanks/Giu

 

Nope, you didn't miss anything....... wait until the iridium is not 'new' anymore, then they come up with more 'new' stuff.... Kryptonit plugs, Unobtainium plugs....

 

My new stroker crate motor has a 750 Holley DP on it that runs really rich at idle. I am running these plugs to reduce the chance that I might foul one while cruising light to light in town.

 

over the years I have tried nearly every gimick spark plug that ever entered the market. fire ring - split fires - Ugrouve........ I was also a person that switched to high powered ignitions because I got stranded once to many times just because of water early in my driving career.

What i have found and it can be backed up scientificaly is: High powered ignitions with good wires cause spark plug tip and electrode errosion. My ignition just eats away standard plugs. So I only use platinum and iridium might be next on my list.

It's a fact that indexing and or multi tip plugs make more power. I used to use the Bosche 4 tip platinum. I have not figured out the equivolent P+4 plug for my Dart heads yet. So I just run these AC-delco.

here is what ACDelco has to say

Professional Platinum Spark Plugs
ACDelco Professional Platinum Spark Plugs are perfect for engines that run on conventional plugs and newer engines that require platinum plugs. ACDelco Professional Platinum Spark Plugs can provide up to 100,000 miles of service before requiring replacement.*

Professional Platinum spark plugs also feature:

Dual platinum tip for improved resistance to spark erosion, fouling, and corrosive combustion chamber environment
A ribless insulator that improves the plug-to-boot seal
A platinum center electrode and a platinum pad lower the ignition demand voltage and reduce possible flame kernel quenching
One-piece integral suppressor seal helps reduce radio frequency interference, meters spark plug energy to help provide long electrode life, and seals against compression leakage
Maximum engine performance over time
A corrosion-resistant shell to keep up with the demands of any vehicle
Spark gap remains virtually unchanged during the life of the plug

 

The difference is $12 a plug......................
This is a nice site for general FYI.... www.edelbrock.com/automotive/sparkplugs.html
I run "cold" C57HCX for racing and "hot" RC9YC for street use, both Champion at $3-$4 a plug.

 

There are several parts on my 68" made from Unobtanium! I will say this as my personal experience. I have a Jeep with a 525 HP small block chevy. I use it at local cruises and the beech. I don't foul these plugs after prolonged idleing in stop and go street cruises. Normal a/c's and others I've tried don't like the richness of a performance tune and start fouling out and making the engine run like crap in front of spectators and it gets embarrassing when it starts dieing constantly. I used to know exactly how much cruising I could do at the local rod runs before the erratic idleing and dieing would start and I would limit the riding of friends and family. Which limited my enjoyment of the Hotrod Jeep.
These plugs carry me through the rod run without stumbling and then I "blow it out" on the way home.
-P

 

OK, a high perf race engine may run better with these plugs but what were people doing before these fancy spark plugs were available? I think they had 500+ HP SB Chevys in the 70s and 80s..... they didn't have to change the spark plugs every 50 miles.

 

I can't speak for those guys because there are people among them like Lars and 427Hotrod that can tune an engine to possibly eliminate this problem. For a part-time hotrodder like me this cut down on all the plug changing.
-P
PS. It's not the 50 miles that gets me, it's the 2-3 hours of ideling in TX heat and going 3 miles at a street cruise.

 

That was exactly my point. Idling around is what gets you. It also was not uncommon "back in the day" to have to "blow em out" from time to time to keep them from fouling. I don't know if the irridium plug can solve this completely but it does help.

 

idling in traffic, at least for my engine, is like a kick in that place...maybe you'll think i go too far, but i always take the car on the highway for at least a 20/30 miles run at good rpms before take back to the garage and put her to sleep, on my opinion, and of course for my application, it's the only way to avoid any problem next time i'll switch her on...

 

The only thing I don't like about AC spark plugs is they seem to wear out suddenly.

One tank I'm getting 17mpg, then the next I'm getting 12mpg. Then I know it's usually spark plug time.

Platinum plugs seems to wear more gradually.

Anybody else notice this?

 

No, I really haven't. I would just like to notice my car getting 12 MPG