for you spark plug junkies, I've discovered something you may want to know.

From what I've read, the general concensus around here is that most people just stick with rapidfires, which are around 4-5 bucks if I remember correctly...

...although there are a few "risk takers" that go against the crowd and buy bosch platinum +4's, which don't really make a difference(though most sparkplugs don't really anyway), but they last somewhat longer.

then denso came out with Iridium plugs, which hasn't been talked about too much on here as far as I can tell...

the new iridium plugs are supposed to last 30,000 miles, and(according to all the tests they've done on the site) tend to give a 5hp peak increase over other plugs.

this would probably be why they charge 13 bucks a plug.

well I just found out that NGK makes Iridium plugs too, and I've found them online for 6.50 a plug, minus shipping(which is 5 bucks).

if you keep shipping out of mind, that's cheaper then the +4's!

so ya, I'm gonna try 'em, screw the supposed hp gain, I'll try em fo the 30,000 mile lifespan(which actually toyota and lexus have iridium versions of plugs that last 120,000 miles, so NGK might have a longer lifespan then denso).

just figured I'd let everyone know.

 

most people just stick with regular AC Delco plugs, they are only $1.19 each. Just stick with these and spend your money on a real mod.

 

now I don't know about anyone else, but I f-ing hate changing the plugs on these engines.

I'm willing to pay more if it means I have to pull em out less often.

 

im sure the regular AC Delco's will last 30K miles if not more.

 

really?

well okay, if thats the case then whats the point of them trying to come out with improvements on the design?

hotter spark is all thats left, that i can think of.

eh, I dunno.

 

platinum plugs last long than regular copper plugs and im sure the iridium plugs last even longer. But for sure if you car is in good tune regular plugs will last around 30K miles or more, platinums i think are 50K and im not sure about the iridium plugs. Do a search, there is alot of info about this stuff.

 

The reason why new cars have iridium and platimun plugs is because of thier durability and lon glife span. However, their ignition systems are not as powerful and prehistoric as our HEI systems. AC delco plugs will last way past 30,000 miles. I mean way past. I have seen some go as long 140K. Not a good idea but you get the point. Anways, these fancy plugs are not a good match for our ignition systems. Our systems are not desinged for them and will foul them out over time. Remember, as conductivity goes up so does corrosivity.

 

Why do you all say that plugs only last 30,000 miles. Did that come from the manufacture web site or something? Not to say that your wrong but I've seen plenty of cars go 80,000 miles on stock plugs. Do you mean that there will be a reduction in gas milage or power after 30,000 miles?

 

The electrodes wear and the gap opens up. After a while, the engine will misfire under load since the gap will be too large for the spark to consistantly jump when there is a good deal of cylinder pressure. Id only use them for 30k. Have used sets for about 45k-50k before it started to misfire.

 

We use those iridium spark plugs in our little 600cc engine. They do nothing for power. We just put them in the engine because they are free . We dyno the engine with normal spark plugs at various gaps... with the central plug position and the COP ignition it's shown no increase in power or throttle responce. The iridium plugs do stay cleaner for a longer period of time. Because of the design (small tip) the plugs will last a lot longer in an engine that's burning oil or running too rich/lean.

 

Just a side note, my boss has 98 Z71 with 300K miles!!!, and the original AC plugs. Stupid, I know, but the he drives like a granny, and the motor still runs allright.

 

I took a chance on a set of NKG V-Power Plugs 4 YEARS AGO when I bought my car. 4 years and 40k miles later the car still runs the exact same.

 

Heres a lil update on the plugs guys...The reason the have platinum and iridium and stuff....Starting in 1996 almost every car came outta the plant with platinums in them..why becuz normal copper plugs do not fire fast enough or hot enough and will throw a computer code i dont know the number but it comes out as a random cylinder missfire...thats pretty much why there are platinums and irridium plugs...if u have an older car than 1996 dont waste ur money it wont do anything for u..if u need a hotter plug just go to ur parts store and have em look thru the catalog for a autolite plug that runs hotter and will cost u 1.28...at least thats what it runs at my work...and the info i got from ASE mechanics and dealerships...i work at advanced and i was taught that becuz i sold some copper plugs for a 1999 chevy s-10 and he came back in with random cylinder missfire and he didnt wanna spend money on platinums when he first came in then i told him his car requires it....if u have a 1996 or newer...run platinums...just not bosch they are junk

 

Don't take this the wrong way but that's a bunch of bull. The only reason new cars put those plugs in newer cars is the same reason they put in synthetic oil... it last longer. This way the car doesn't come in for service under the warrenty period. Trust me, this is the reason. Nobody buying a new car changes the oil 3000 miles or 3 months! Synthetic oil will last 30k miles, ask Amsoil, we're sponsored by them. I'm sure engines could go longer without an oil change but in the rare cases where somebody does roast a motor from not changing the oil, the dealer just asks for records on when the oil was changed...... deal wins.
As for the guy that said he was getting a misfire. Just guessing here but I have a feeling he dropped a spark plug on the floor and didn't bother to check the gap (closed). Or he might have damaged the plug wires, not on enough, etc.
Those plugs have nothing to do with being hotter or better. All they are is 2 electrodes, just about any conductive metal will work. Only aluminum would melt and copper also has a limited life.
An ignition system is upgraded with things that matter, like low resistance wires, better coil, cap discharge, CNP, and COP. Then messing with the dwel times.
Now to be completely fair, there is a chance that a misfire could happen with normal plugs... cold heat range. A copper plug will be more sensative to running rich and fouling. In new cars they run really rich on initial startups to heat up the cat and o2 sensor. The misfire could probably have been solved with a corrected gap and heat range.

 

You dont even have headers. Its not that hard to change plugs on the stock exhaust manifold.

 

it's a bitch to change the plugs on these cars, headers or no.

having to lift the car off the ground, for starters, is more then i personally think should be neccessary, but hey, that's just my opinion...

...I do LOVE these cars though, don't get the wrong idea.

anyway this thread was started forever ago, and just so EVERYONE knows, my car is sportin' ac delco plugs, and probably will from now on, but also, just so EVERYONE knows, when I removed the bosch plugs they were still in perfect shape, and they'd been in for a year.

I only changed 'em because my father was determined that I use the plugs that were designed for the car.

 

I removed all the AIR plumbing and such from mine, and I can get all 8 from on top. much nicer.......

 

The "real" spark plug of the future? Wish I could find the link (I think it's on a different computer). Last I saw it was still in development, but the spark gap was contained in the head gasket, producing spark around the entire perimeter of the combustion chamber. Reliability was apparently not an issue (becomes a non-maintenance item), power, economy and emissions were improved. Of course, the up-front cost is dramatically increased.

 

I'd take a wild guess at no.3 misfire in that situation. Those newer S series trucks have a huge flaw when it comes to changing the plug on 3 even if you have the correct tool theres a good chance of cracking the plug.

 

Wow, it amazes me how much misinformation is on this site. Iridium has been around for a while. As for conductivity:

Copper:
Thermal conductivity 401 J/m-sec-deg
Electrical conductivity 595.8 1/mohm-cm

Platinum:
Thermal conductivity 71.6 J/m-sec-deg
Electrical conductivity 94.34 1/mohm-cm

Iridium:
Thermal conductivity 147 J/m-sec-deg
Electrical conductivity 188.679 1/mohm-cm

As you can plainly see, COPPER is the best conductor of the three. That is inclusive of the thermal conductivity. That said, the latter two in the above list are much more durable substances in the combustion environment. When the big thing a few years ago was the 100,000 mile tune up, it was Platinum and Iridium plugs placed in the motors. They are produced for durability and durability only. You will note that a lot of companies do not use full sleeved platinum or iridium.

There is a drawback to their durability, as stated previously, in that their conductivity relatively sucks donkey *****. You can not use full platinum plugs such as Bosch platinum and Bosch +4 with a capacitive discharge system (not sure if anyone makes a full iridium plug but allegedly the stock v-8 SHO ones were). The resistance will either ruin the plug or the capacitive discharge system or one of the ignition components.

For these applications the consensus has been the regular Bosch (solid copper core) AC Delco or Champion plugs.

Now as far as changing the plugs, I’ve owned about a dozen of these cars and always pulled them from the top with little problem. :shrug:
As far as the less powerful ignitions of today… where? The output is comparable for the most part, they are all ‘HEI’ ignitions now a days.

As for our cars fouling the platinum and iridium plugs, that is pure BS. That is one of the good points of all that resistance and minimal electrode surface area, they self clean rather well and stay cleaner longer.

Now don’t take this the wrong way, but…for the first part…that is just pure unqualified BS. See the conductivity listed above for each, copper will fire faster and easier than either of the other two, however, the delay is so small that you would need a nice lab set-up in order to measure it. As far as the second, please qualify that statement. I have heard of some problems, but never that they are junk (and I’ve been looking into them since before Mr. Rahal was racing with and promoting them). They have probably the best durability on the market for platinum plugs. The only drawback is you have to play with the plug end on some. What’s your reasoning behind this unqualified statement?

Five7kid… pssstt… linkie please. Are you referring to the rimfire hemispherical head?

 

hey freeloader... I dont know if anyone mentioned this since i didnt feel like going through every single post but... I work at Pep Boys. We carry NGK Iridium plugs for $6.99. Have for quite some time. Most large auto parts stores will. Just so your not payin for shipping.

 

well, while we're on the topic of thermal and electrical conductivity...

...gold is actually the best conductor, period...

...so why haven't they bothered to make any plugs with gold?

and if not gold, silver is the next step down, so why not that?

they could do the same thing that they did with iridium, mix it with nickel to make it strong enough to remain solid and withstand the heat...

I'm sure we stuck with copper originally, because it's FAR cheaper (although that's changed somewhat over time), but platinum and iridium are entirely different cases...

any ideas?

 

I didn't bother to go to pep boys, but I had originally tried discount(now advance) auto parts, and while they had them online, and had them on their computer as something they kept in stock, they in fact DID NOT keep it in stock, and had no intentions of ordering any.

oh, and at the time autozone didn't carry them at all.

if at some point I decide to try those plugs though, I'll know to head to pep boys then, so thanks for that.

 

Silver is actually a better conductor than gold. Gold is used more frequently in electrical connectors, however, because gold doesn't corrode, and silver most certainly does.

I dont' know why they haven't come out with a gimmick "Gold" plug.

EDIT: I've never heard of that "perimiter firing" thing mentioned above, but it sounds cool. One thing I HAVE read aabout is something developed by SAAB that was pretty neat. There was a cone shaped piece on the top and center of the piston. The spark plug hole was tiny (like 10mm) and just featured and electrode. The spark would jump from the threaded-in electrode in the center of the head to ground on at the tip of the cone on top of the piston. Talk about NO spark shrouding! The spark shoots right, directly through the primed charge. I thought it was an excellent idea.

-Tom

 

heh, lets just hope you never develop any kind of knock...well, you wouldn't, the engine would just flat out die.

heh, we have the engines that run forever but never right, and they've got the engines that run perfect or not at all.

 

I posted a question about the electrode being the piston and got a reply from Grumpy. He looked into before me and said that there were complications with the piston rings. Sinde the spark was jumping the gap from the plug to the piston, it would then need to find ground and the piston rings were the path of least resistance to the block ground. Just like spark plugs wearing down you can imagine what would happen to a sharp edged piston ring.... no longer sharp. Hence wear problems. So if you think changine your spark plugs is hard, just think of the poor guy that has to also replace his piston rings, lol.

 

There are more places for electricity to go to ground than the rings. How about the entire piston skirt? How about through the rod to the crank?

The amount of surface area for which the spark can find ground throughout the entire piston, rings, rod journal etc is so GIGANTIC compared to the tiny electrodes on spark plug plug. Pistons and rings will wear out from friction before they wear out from errosion, IMO.

-Tom

 

Gold itself may not corrode, but I do know that you want to be real careful with gold and copper together. I cant tell you how many computers I have taken apart that have the gold connectors in the slots on the Motherboard, and copper connectors on the ol' ISA cards that were rusted together. They dont mix well.

 

Well you're wrong. It was a problem. Keep in mind that the jumping a air or oil gap increases the resistance by a LOT. The rings are ment to seal the piston to the cylinder. If the cylinder is grounded (as it would be) then the rings, not the piston skirts are the path of least resistance. The skirts shouldn't be touching the cylinder wall under normal operating conditions, the rings should. Hence rings have the path of least resistance (also touching piston). For the spark to travel through the rod and into the crank and then into the block takes 3 "jumps" through thin oil gaps. That is definatly not the path of least resistance.
If you want I'll try and find some more direct information about the issue.

 

um, jewelers mix gold and copper all the time to improve the strength of the gold itself, and keep costs down.

that's what the karat rating is.

anyway, a certain level of humidity is required for them to even begin to rust, and under normal condions no motherboard would ever reach that level, it's too hot in the first place.

are you sure they didn't melt together? I mean if someone upped the voltage the excess heat generated from the copper ISA slot could have caused the (i'm not potsitive, but they're probably near pure) gold to melt.

p.s. this is slightly off topic, and is a rhetorical question, but WHO STILL USES ISA SLOTS???

...I just wanted to say that.

and just so we're not too far off topic, the fact that gold and copper are often combined gives even more reason to question why no one ever bothered to use a gold electrode...eh eh?

 

Lots of people use ISA slots. Most companies are still running at least a few Pentium 1 and some companies still have some DOS machines out there running thier inventory software. I work on them on a daily basis. If you dont believe me, thats fine but it is true. When you mix and match the two on a motherboard, they will corrode. Not maybe, not possibly, they will. BTW, I am postive of what happened, I repair motherboards all the time. They do not melt together, they corrode. All of the facts about mixing in alloy is fine, but a motherboard is not a mixture. A motherboard connection involves the transfer of electricity from one to the other. Thus inviting the corrosion. Also, if you think that mothorboards are too hot to have moisture or humidity there, then this is a moot argument anyway.

 

couldn't they have built some sort of ground into the tip so it didn't move to the piston ring, or maybe even changed the material the rings were made of so that either they didn't attract the spark, or so that they could take more of a beating?

 

The rings have a very important job to do. I don't think it would be feasible to get the spark from the piston to a ground without going to the rings.
For a race motor it doesn't matter, F1 does this but look at the tolerances. They don't even use head gaskets. I did get the chance to see some prototype carbon fiber pistons. They were so damn light. Anyways, I didn't get the chance to see the rings but the piston had cracked because the sparking left a large divot on the top. Just stick with the good old spark plugs.

 

What a PITA it must be to check and set gap on that? And what happens when the tip on the piston wears? Or gets covered with carbon?

What a horrible idea. Just like most other manufacturers these days, they are over-engineering the vehicle. Just making things more complicated than they need to be, just to show off a new idea. Can you? Sure. But should you...?

 

I remember seeing an article on the Saab as well. To make it even more complicated I think the upper spark plug part was part of the injector as well. The spark plug fit through the center of the injector which fires directly into the cylinder instead of into the intake tract. I too wondered about ring problems when I saw this setup. You can allready have micro welding of the rings in the grooves, what happens when you add electricity to the mix as well.

 

I must admit, sometimes SAE gets a little crazy on an idea but it's usually not something that'll stick. A perfect example was (again) Saab and there variable compression engine. I LOVE the idea but it required such a large case that it wasn't a profit making option. Nobody really cared that they got 2 more mpg than they would have without it. Just too much hassle.
Keep in mind that they said this about 4 vavle cylinder heads when they came out.... history will tell.

 

variable compression engine?

how would adjusting the compression allow for more gas mileage?

 

Higher compression engines are more efficient than low compression engines, generally. Most modern engines have around a 10:1 CR (or higher!!) because of this.

 

I remember reading about the saab motor also and think the reason for having variable compression was so they could also use a supercharger but don't hold that against me if I was wrong
but the compression was variable from like 8:1 up to 16:1 compression all by having the block(inline block) tilt at an off angle to the crank thereby bringing the head closer to the pistons

but this way when you are just cruising around town being that you are not having a very high volumetric efficiency which creates less cylinder pressure. since you have less pressure you can add some more compression to the motor (16:1) and as you give it more compression will decrease to prevent pinging.

 

http://www.autospeed.com/cms/A_0458/article.html

 

I understand that higher compression= better gas mileage, but that was why I didn't understand why you would want to adjust.

that article didn't really answer the question either...

the only thing I can think of would be to lower the compression so you didn't HAVE to buy high octane gas, otherwise, wouldn't just having the highest possible compression at all times be the best route to go?

I mean, isn't that essentially what the diesel engine is based off of?

 

there is a difference between dynamic compression an static compression
static compression is the compression ratio from full cylinder volume vs compressed cylinder volume
dynamic compression ratio is a little different and takes into account how much air you actually brought in

ie you have a 100ci cyl at BDC but at TDC it is 10ci
that is 10:1 STATIC compression

during normal operation though you hadly ever reach 100ci of intake for that cylinder
maybe 80ci at wot
and lets say at cruise you are running 20ci of air intake
so lets calculate the dynamic compression

dynamic compression takes the amount of air drawn in vs the total compressed volume (10ci in this case)
so 80ci of air intake with 10ci of compressed volume means 8:1 DYNAMIC compression which isn't that bad
or when cruising since you only pull in 20ci of air for this cyl you are now at 2:1 dynamic compression..... not so pretty huh

now lets bump the compression up to 20:1 compression
wchi means our 100ci cyl is now compressed into 5ci so now lets do the new math
that 80 ci at wot would be 16:1 dynamic compression.... little too high (might be able to see some of the reason to have variable compression might come in handy)
and at that 20ci of intake during cruise you are now pulling 4:1 compression.. much better then 2:1 compression wouldn't you say?
now lets see a turbo motor at 8:1 STATIC compression
100ci leaves about lets say 12.5 compressed volume
during cruise you are getting a whole 1.6 dynamic compression ratio (20ci of air/12.5 compressed volume)



when you are driving around town you are not pulling as much air in which means less cylinder pressure.
when you are driving at wot throttle you are sucking in more air which means more pressure
when under wot and boost you are sucking in even more air which means even more cylinder pressure

what this variable compression allows (as per my previous post) the ability to run high compression when cruising around town
then when you stomp on the gas the compression goes down a little to prevent pinging
and then a little lower compression to allow for the boost when you really want the power

the more air you pull into the motor the more pressure you have when the combustion happens
you get too much pressure you start getting into detonation

like have you ever heard about a car running 16:1 compression on the street?
prolly not cause if that guy hit the gas hard he is going to detonate to all hell

but if you can cruise around at 16:1 compression then when you start getting on the gas and the cylinder pressure starts going up have the static compression lowered it will keep you out of the detonation zone

or try running 16:1 compression under boost.... good luck
but 8:1 compression under boost works fairly well

this variable compression gets rid of the comprimise of running only one stati compression as you should be able to see above in my examples
so this variable compression should allow you to be in an optimum compression ratio for cruising. WOT. or boosting.

and when running higher compression you tend to have greater efficiency on the compression and how the fuel burns, as well as higher volumetric efficiency and stuff


sorry if this is kinda pieced together at work at tired

 

that actually makes complete sense, thanks.

 

Just to confuse everyone even more, I learned there is a difference between DCR and something called kinematic compression.

A lot of calculators online use a vague means of calculating what they call "dynamic" compression, when it's really kinematic.

I'll quote someone from another board where I learned it. Keep in mind this was addressed to someone specifically asking about this calculator.

http://members.uia.net/pkelley2/DynamicCR.html

Of course I questioned this because I wanted to know more.

This is what he explained.

Fantastic explanation if you ask me. Helps point out that fact that no matter how much we like to analyze things using a computer, it'll never compare to real world.

 

Any of you others have any experience with EDM? If you've ever calibrated or either aligned or repaired their power supplies, or even understand the concepts, you might want to apply those phiilosophies to the ingnition system that grounds to the piston top. Aside from the other mentioned potential problems, grounding through the rings, rod, and main bearings might not be the best idea for overall engine longevity. Blasting even small amounts of current through the oil film on the cylinder walls and/or hydrostatic bearing surfaces would not be very good for the oil either, and the resultant carbon liberated from the iron and oil could severely shorten oil life.

If it were such a great idea, we'd probably already see it in racing, where oil, bearing, and engine life are not critical. If it turns out to be a crappy idea, we'll likely see it on Daimler and Mitsubishi vehicles soon.