Wrecked82

Over the weekend, replaced acdelco platinums with ngk iridiums. The acdelco had probably 40K miles on them, but looked with slightly light brown stuff on them. All looked alike with one having some extra brown stuff buildup on one base. Anyway, to the point, the iridiums really made a difference in areas that are advertised. Idle quality is much improved. Acceleration is improved. Sound is deeper but also quieter at freeway speeds (which mean 80 to me). So, were the spark plugs bad or are the iridiums really an improvement? I remember in a very recent Corvette Fever magazine (on dynoing?) they mentioned they replaced all plugs with ngk iridiums when comparing before and after results. If they don't make a difference, why use them over non-iridiums?

ray77vette

i have already thought i could feel a difference with new plugs, but then again a car with a full tank of gas runs better than an empty one. if there is a difference probably a good part of it is now they are gapped correctly.

Wrecked82

I usually check the gap on the old ones out of curiosity. All were at .047 - .048. Gapped the iridiums at .045. Came gapped at .040.

comp

i read alot of different articals on tests (yes some ricer) it looks like some
combo's do like them,, :thumbs: but a fresh set of something else may have
helped to, i've never got a set of standard Bosch plugs to last in my truck &
AC are ok it's stupid :banghead:

Pete76Shark

About a week ago I watched one of the club members run his car on the dyno with platinum spark plugs. You can see on the dyno prinout the HP falling off at RPMs over 4K, and this is due to the platinum coating slowing down the spark. First question the dyno guy asked after looking at the dyno printout is do you have platinum plugs !!.. Experts in my club and the dyno guy all said switch to NGK copper if you are looking for performance. But the NGKs will clog up quicker then the platinum.


[Modified by Pete76Shark, 7:35 PM 12/30/2003]

Larry3x2

I agree with idle quality improvement and economy. Just got the same effect on my LS1 truck engine at a 70K plug change against a 100K requirement.
In my "69 BB Corvette we tried different plugs with the engine on the dyno after a fresh rebuild and they made zero difference. From standard AC's to bosch platinum etc.
Larry

467-Ratman

Larry, I found out first hand this summer at the chasis dyno that plugs can make a big difference! I was running a set of plat rapid fire plugs, and the first question after the first run was , what type of plug are you running. He took them out and went with a set of good old Champion. The difference was 20 more hp!!! Also I was told later by a friend at MSD not to use plat plugs with the MSD setup, something about the platinum not dissapating the heat very well. All I know is finding 20 hp with one easy change was pretty cheep HP! :hurray:

Jadee76

A few yrs past i tried a few of the exotic plugs in my 76 because i needed
the economy as to driveing a lot and traveling. At the end of every 5000
miles i would try a different brand of plug at the same time recording
the results. other than air filter change the engine tuneing remained the
same so as not to offset the results. After trying the popular brands(expensive) and tallying up my results my conclusion was that if there was
a difference between them and the ac plugs it was so minute that it
wasnt worth the xtra money. This is based on my results only.
so i will stick with the ac. Hope this helps
jadee76

nastee383

I thought about putting iridium plugs in my supercharged Grand Prix when I changed them. That is until the guy told me they were $8 a piece. Just couldn't bring myself to do it.

DennyM

I just read an article in Feb issue of Corvette Enthusiast about Bosh Platinum +4 plugs. They showed the differences on a dyno between the +4 plugs and TPIS wires, and the stock verison. They ran the test on a C5.
Probably worth reading.

Disco_Mike

AC plugs have worked efficiently for 60+ years in my family. Call me old fashioned. for their price you can put new ones in every year. (provided you want the aggrevation.)

BSeery

Don't use the platinum or other 'fine wire' spark plugs with NOS, high compression, turbo or supercharger. The "wire" will basically evaporate.