What are you running in your 350 thats given you better performance? I am running Bosh platiums and they do run better than AC

 

My 94 has 60k miles on it and runs perfect. I pulled the original plugs out and they looked so good I just cleaned the threads, put on some anti-seize, and put them back in.

 

The only advantage of platinum is they last longer but they have higher resistance than the copper plugs. Copper should run better.

 

I just use an Autolite 3926 and change every 2-3 years. Never like leaving plugs in longer.

 

SOTP better? What makes you think "it runs better"? I am sure it ran better than old plugs, but have you put new AC's in then the Bosch's and ran back to back dyno pulls or 1/4mile?

The only way I know to get more power from a spark plug is to run a lower resistance plug and wires so it uses less energy to get to the tip of the plug allowing for a bigger initial spark. This can be done in conjunction with a higher powered ignition and allow for a wider gap. Again... all about getting a bigger spark. Also in boosted applications, the extra energy helps because air has an extremely high resistance and poor conductivity. So, jumping the gap reliably can require more energy at the tip.

All this said, there is another item not looked at. That is where the electrode orients itself in relation to the piston and where the air/fuel charge settles in the combustion chamber. This ofcourse is on a very "atomic" scale because there is enough fuel in the mixture to ignite regardless of electrode position. Though, if you are trying to squeeze every last 1/4hp out and have the money, you can buy 50 plugs and index them once installed and run a matched set of 8. Some race teams do this.

All in all, the spark plugs can't do much to increase air flow or add additional fuel. So they can't add more energy to the thermodynamic equation that governs the reaction in an IC engine. All they can do is help ensure all the air/fuel mixture is ignited fully earlier.

So, with Platinum having a higher resistance than Copper... what real world improvements do you expect to see from spark plugs?

 

The only thing that makes my car run better/smoother is being driven regularly, or after a spirited run she just purrs so smooth. If new spark plugs made your engine run better, either the old ones were the wrong kind or were simply left in way too long. Not sure about the L98 but the LT1/LT4 engines came with platinums, good for 100k (as long as the engine was maintained in good running condition).

 

Materials are about longevity. The conventional plugs wear quicker and the gap opens reducing spark intensity. Platinum and Iridium plugs stand up to wear longer. That is why they can stay in the car longer. However, a poorly running engine can gunk up a plug and reduce it's life long before 100K miles.

 

Yes, that is exactly why I said good for 100k as long as the engine was maintained in good running condition.
Conventional copper plugs may result in a slightly stronger spark but not enough to actually increase performance -- either the fuel charge is being ignited, or it is not. That's why many knowledgeable people call BS on the splitfire and E3 "performance" plugs. Everything else being equal, the only way a plug can be better than another is in how long it lasts in the engine (iridium/platinum).

 

AC's are fine. Very unlikely you could tell the difference

 

While we agree on some points, I will disagree that plugs can't add or subtract performance. Based on the kernel size that can be produced and how much spark energy occurs in the gap the ignition of the charge mixture can be affected... on an atomic scale. Also as I mentioned above there are favorable locations for the electrode to appear. This difference is small and not something you would be able to feel between sets of new plugs.

 

Because the performance boost is so small, I was generalizing for the purposes of a simple discussion. I'm sure you are right, at the atomic level. If we were in a racing league at the top of our class, competing for the championship, every tiny boost in performance would matter a great deal. Also, we would likely have a budget for nearly every performance enhancer available: fuel stoichiometry, tire selection and wear/deflection, aero adjustments, etc. But for a simple driving enthusiast such as myself, the performance benefit from a different spark plug is negligible. I am not running race gas or a hot cam. Changing plugs on the LT1 is not easy and I put a lot of value in knowing I can comfortably run a set of iridiums for 80,000++ miles. And they are igniting the fuel charge just fine, for me

 

Exactly

 

I am running iridiums in my 77 stock L-82 car. It will not run on the stock plugs! I have a car with 140,000 miles on them with no issue! Copper is a better conductor but who cares i was just looking for something better for performance. My 93 LT1 has the original spark plugs but i will use the spare set of original AC i have if needed. Thanks for all your opinions!

 

That makes no sense. TBH, I would have to see it to believe it.


Physics and electrons. Things that matter care about conductivity and resistance. You wiring harness sure does too.

Good luck with that from spark plugs. In short - the difference is so small you should never notice. Any wild claims from a spark plug company about added performance is snake oil. Engines convert energy from gasoline into rotational energy. Thermodynamic law states energy cannot be created or destroyed, only converted. A spark plug injects energy in the form of a spark for a millisecond. It cannot add additional energy to the combustion process beyond that.



These are not opinions, it is science. If there was an actual spark plug that could increase power significantly, they would be all over the magazines and everyone would use them in their builds. Everyone has a preference and that is fine. There isn't enough difference from one plug to another to significantly change the end result.

 

No. Those are good.

 

I replaced my stock AC Delco's with new ones. They seem fine as they are new. I would not buy them again because they are Made in China. I would like to find a brand that is not. I don't know if GM has just forgotten about it's older cars and everything is just contracted out or what. I have a 350 in my '93 Fleetwood as well, I imagine it takes the same pugs so I'll be shopping around.