Z QQH 6

Ok, what is the preferred spark plug? I was thinking of going with AC Delco new Iridium plug #41-985. I have 01 Z with a cam and the usual bolt ons. is this too hot a plug? What would be the plug to use?

Bink

NGK TR55 - excellent plug for stock CR, NA. :thumbs:

Vetteran

Just tonight I installed NGK Iridium IX plugs (gap: .050)! Kept the stock wires. I've read many posts where guys have experienced missing pucks with the stock plugs, this can't be good for the cylinders. Wouldn't have done this with only 3,200 miles otherwise.

The NGKs run great, very smooth idle. If you haven't done this before, get yourself a spark plug wire puller. The one AutoZone carries works good.

z-u-later

:iagree:

MC TORCH RED

ngk's tr 55 work for me... :yesnod:

IVOZO6

I installed NGK Iridium IX plugs. Very nice, smooth response :cool:

RWTD

Denso IT16 with a .050 gap. http://www.densoiridium.com ABSOLUTE best plug in the world, and the finest tip of any plug! 75% of '03 Cobra and Lightning owners use these (albeit with a colder gap, however).

I have them on my site here:

http://www.runninwiththedevil.com/denso.htm

Here's a cool misfire chart of them in action, compared with other popular plugs (test was done by a Lightning owner, while in school in his lab):

Click on the picture to make it larger and more clearer:



Sincerely...


[Modified by RWTD, 6:09 AM 1/2/2004]

00pewterpower

I just installed the ac delco 41-985 iridiums with magnacore 8.5 wires. Local parts store did not have the ngk iridiums. They look to be good quality, all gaps were identical at .040. Runs smoother at idle and these plugs are rated at 100,000 miles. Just happy to get rid of the platniums before they came apart. :seeya

Z QQH 6

James: Impressive chart.

V8_Club

NGK TR55's :thumbs:

Allthrottleandsomebottle

I have the GM #12 Rapidfires in the 00', TR-6s in the 97'............
I have an interesting test case to visually show the misfires that happen normally on engines as the chart above show..........
I have a 72' El Camino SS with a 350 in it. The lower header on#2 is rusted away for about 1 " oval at the bottom............you can see and hear the random misfires at night, funny thing is the exhaust pipes pur like a kitten :D :thumbs:

C5XTASY

ttt

Noggles

:withstupid:

this is the one to have. :yesnod:

vettman10

So why has no one commented that the Bosch +4's beat even the NGK's with the lowest misfires on James's chart??? I use the Bosch +4's in everything I drove and have nothing but praise for it. It is without a doubt the most advanced plug available, and is a true 100K mile plug. Its the only plug that has shown a true horsepower gain in dyno tests. MTI claims 5 hp. That's not a lot, but its 5 more than everybody else. No, I don't work for Bosch, I'm just puzzled why it doesn't get more positive comments on this forum.

RWTD

Bruce,

I normally find the reason to be that they are not a good choice for NOS or S/C, Turbo combinations (one of the reasons being that you can't gap them). Plus, they are platinum, and many racers frown from using such metal on the plugs. Although platinum is not the best choice for a performance style plug, the Bosch +4's do a remarkable job at keeping misfires to a minimum (although the Denso Iridiums are still the king here).

Now, with this being said, Bosch makes a Silver/Copper version of these plugs, but it's only sold overseas, and not in the US here. They have a silver-plated center electrode made of chrome-nickel alloy with an encased copper core, and both of these materials are the best conductor of electricity, aside from Gold. You can read more about them here:
http://www.boschautoparts.co.uk/pcPlug4.asp?c=2&d=1

Too bad they weren't sold here in the US.

Anyhoo, I don't believe that they give 5 more rwhp than a Denso, and I believe that the only way a sparkplug can allow a vehicle to make more power is if the sparkplugs in the vehicle aren't a well performing plug in the first place. Naturally, a bad sparkplug can inhibit a vehicle from making maximum power, however. The key is to find a sparkplug that has very low misfires, works excellent under stress for the given vehicle's mods and circumstances, and has a proven reliability rate.

Sincerely...


[Modified by RWTD, 8:25 PM 1/12/2004]

vettman10

James,

The reason they actually provide boost in power is that the spark is not 'covered up' by the ground electrode as it is in conventional plugs. In the +4's, the spark travels laterally from the tip of one of the ground electrodes to the tip of the center electrode, thereby allowing it to be totally exposed to the combustion chamber. The NASCAR and NHRA pro guys have known this for years and so took time to cut back the ground electrode until it's even with the outside edge of the center electrode to get better spark exposure. Now, Champion and others manufacture certain 'racing' plugs with the ground electrode already cut back. A lot of folks haven't noticed this feature of the +4's.

Bruce

RWTD

Bruce, nothing against your intellect here, sir, but I must wholeheartedely disagree concerning that the Bosch +4 plug provides a power increase over another high quality, minimum misfire plug, in modern day DIS ignition equipped vehicles.

The theory of those plugs is sound, tested, and true, yes, however.

Now, if you want to see a trick plug, check out http://www.torquemaster.com/

I'm fairly positive that Bosch came up with their +4 design from this plug. Many companies have tried to buy his design/patents, but he refuses to sell.

However, some DIS ignition systems do not like this plug (or at least did not back in the times). They never worked right in the 99-04 Lightnings when quite a few tested them. I believe the owner of the company was developing a new version of it that would right, however. I did have a 92 Talon Tsi AWD that they worked perfectly in, and it was DIS (Distributorless Ignition System).

Sincerely...

vettman10

James,

After I re-looked at the misfire chart you posted I see what you mean about the Denso's - its misfire rate is basicly zero, very impressive.
The tip on that 'torque master' plug is interesting, but not that new. Champion has been selling plugs with a similiar tip for outboard motors for some time. And I remember seeing ads in '60's era JC Whitney catalogs for a similiar plug. It is puzzling why the "surface discharge" type tip hasn't caught on that well with automotive applications.

P.S. I'm considering purchasing a Predator for my '01 Vette and have a question on its diagnostic capabilities. Can it be used as a scan tool on any ODB II vehicle? And what about on ODB I vehicles with the appropriate cable adapter?

RWTD

Hello again. It'll work on most all GM vehicles that are OBD-2 compliant. It'll only do OBD-2 and not OBD-1. I'm not sure of any devices that have both systems in one.

Sincerely...

C5XTASY

I remember those J. C. Whitney plugs, also. If memory serves me right, they were called "SPITFIRES".
Ed


[Modified by C5XTASY, 3:33 PM 2/10/2004]