Spark Plug Choice for MPG? hotter spark?
 

I have a table here with gram per ampere-hour rating on types of conductive elements

copper: 2.37
platinum: 1.82

im pretty sure the higher the number on this chart the more conductive an element

I would think copper plugs would provide a hotter spark on some applications an perhaps increase mpg? im not sure about plug mods for mpg.... anyone know?

regardless I read that even thought autozone will sell my platinum plugs for my car, I should be using copper ones, could this be part of the reason? and is the big fuss about platinum overblown?

1) Ford = Motorcraft or Autolite
2) GM = AC Delco
3) Chrysler/Dodge = Champion
4) Toyota = Nippen/Denso (ND)
5) Nissan = NGK
6) Honda = Nippen/Denso (ND) or NGK
7) Most German Vehicles = Bosch

this is what I read
and saturn (copper) ngk's

Even new Chrysler vehicles still come with copper Champion plugs. Their long-life OEM plug is a Champion platinum but it isn't a fine wire, it's a copper electrode plug with a small disk of platinum welded to it. They are also the only manufacturer I know of that still use projected tip plugs.

The whole point behind Platinum is long life, Iridium has a finer wire electrode so better control over when the spark occurs can be had and they can run ignition timing to the edge. The Civic Si running 50 degrees of spark advance at 7800 rpm is an example. You need good control over spark timing at those engine speeds.

Also, ampere hour ratings aren't going to help much when talking about the best electrode. Spark plugs don't fire with much more than 50-75mA of current. Yes, copper is more conductive but none of those metals are bad enough conductors to cause a decrease in spark power. I've got images of them firing off in a pressurized chamber but can't find them... might need to re-shoot!

First of all, most cars with electronic ignitions require resistor plugs, so if the plug isn't naturally resistive enough, they make it so. Copper plugs will also wear much faster than platinums. Platinums will fire a more consistent spark over a longer installed life. There's a reason the manufacturers have switched to equipping their cars with platinums. Platinum plugs also heat up to optimum temperature quicker than copper plugs. In some cases the car may not meet emissions or CAFE requirements without them.

I would not recommend switching out your factory equipped platinums for copper plugs thinking you're going to get better mileage. If you are nearing (or have exceeded 100,000 miles) go ahead and get a set of OE replacement platinum plugs, OE wires, and an OE distributor cap / rotor (if equipped)

oh, the case with saturns is copper's are fitted from the factory, ngk's 8543
and from what I know platinum are NOT supposed to be used on these cars!
This might have something to do with the aluminumn block and chemical composition..

people on saturnfans.com rave about it, there are alot of serious mechanics on that site

I think they are referring to the platinum in the electrode interacting with the aluminum in the cylinder head like HHO is supposed to do with platinum plugs.

FYI, aluminum blocks have iron cylinder sleeves. Only low horsepower lawn and garden engines run an aluminum cylinder wall.

Actually GM developed the nicka-sil aluminum blocks with no iron liners in the early 60s. They were used in the 215 Olds V8 which was turbocharged and made 215 HP and weighed 215 pounds complete.

That same design was sold to Rover and used on their Land Rovers for a very long time.

Porsche and Mercedes also used the same design (not sure if they paid license fees to GM or not). Porsche used it in the 928. Mercedes used it in their 3.5 and 5.0 V8s as well as the 5.6. They may still be using it today, but I am not sure of that.

There may be other manufacturers that still use the nicka-sil aluminum cylinder walls today, but I haven't followed the technology in the last decade.

You could not bore those blocks because you would remove the nicka-sil coating on the cylinder walls.

regards
gary

any specilaty plug, platimun, Iridium, etc., only work because other parts of the ignition system are weak. This is in Dr jacobs book. those exotic metals have very high resistance, hence why the center electrode has to be so small. Dr jacobs always stated that autolite plugs last the longest.
hotter coils, better wires are the answer and modified plugs, which I do for all my vehicles. Also measure the ohm resistance btwn plug brands, they are all different. https://www.musclemustangfastfords.co...ech/index.html by David Vizard tells why the plug mod works.

I like using the auto lite 4164 which has a necked down center electrode and then mod the side electrode, for my application.
https://sparkplugs.com/more_info.asp?AAIA=&pid=8304

https://www.autolite.com/pdf/SparkPlugTypes.pdf see #11 high nickle chrome alloy, nickel is a very tough metal.

also very good reading www.magnecor.com for the best plug wire design. low resistance is not the key in todays street cars.

lowest electrical resistance of metals is
1. silver
2. copper which is very close to silver
3. aluminum
4. gold
5. everything else is much, much higher.

From my experience with platinums in a Saturn SC-2 (1.9 liter DOHC), they cause misfires. I don't remember what everyone said was the cause, but I believe it had something to do with the "waste spark". I had the best results from Autolite resistors.

Some of the exotic brands might be running a coated aluminum cylinder but I doubt those owners are on here. Sleeving is what the vast majority of manufacturers have gone with for a long time, especially in the economy cars popular on here. I did have a nitro truck that ran a brass sleeve with a chrome plating on it but it also redlined at 42,000rpm.

I've thrown countless types of plugs on a scope with a pressurized chamber. Assuming they all have the same gap Iridium plugs fire at the lowest voltage, followed by platinum, and copper last. If the resistance of the metals makes a difference it isn't enough to worry about. For the record, the copper plugs fire at around 35kV and the Iridiums at around 28kV.

ONLY NGK's for Saturns,

thanx