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Discussion Starter · #1 ·
Hey TD community, holy cow, it has been a while. I've missed you guys, life just kind of swept me along. TO THE QUESTION!!

First, I know this is basic stuff, but understand that it's been so incredibly saturated, I could not find much useful information relatable to my application.

Car: 1989 Dodge Lancer Shelby TII - Stage 3 ECU

I run 12psi in the winter and 15psi in the summer.

Plugs and Wires are in need of replacing. I'm planning on getting Champion RN11YC plugs as this was the best option I knew of 4-5 years ago. If there's a better plug out there, I would love to be informed.

As for wires, I cannot find much info at all on what to use. I'm using my stock Mopar coil, rotor, and cap.

If anyone knows of good wires for a similar TII setup, please let me know!

Again, apologies for the n00bish thread here guys, I'm just rusty and out of the loop on our cars at this point.

Much appreciation,

Zachary.
 

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You are going to get all kinds of opinions on plugs.
I have been using Autolite Single Platinum AP65 for over 20 years now and with over 200 1/4 mile passes hitting the stripe at 6100 RPM's in 3rd gear @ 12 lbs of boost and I have NEVER had an ignition misfire or any types of problems with plugs/wires/cap/rotor.

The reason for using a single platinum plug is simple.
On a standard ignition system such as ours only the center electrode wears.
The Platinum tip will prevent the electrode from wearing for up to 100,000 miles so you not have any issues with plug gap widening and ignition KV requirements increasing as you would on a standard copper tip plug.

If you do not prefer Autolite then Champion make a single platinum plug #3405.
The only reason I have been using Autolite is they are readily available locally while the Champions are not.

As far as wires, you may get opinions to upgrade to 8 mm wires.
Me, I do not see any reason for that especially with a stock ignition system.
Accel makes a direct fit wire set that has been on my car for 8 years now with no issues.

http://www.summitracing.com/parts/acc-4057/overview/year/1990/make/dodge/model/daytona
 

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Platinum plugs are terrible, they have given me problems on every single dodge 4 cylinder I have ever used them on. Misfires have been common for me with them, I refuse to use anything but good ol copper these days. Autolites work just fine for me...up to about 27psi...have tested past that. But then, mine is a 2.4 and not a 2.2/2.5 so take that for what its worth...I had similar issues with platinum plugs on my Ford 2.3T, autolite coppers there as well. Whatever type you end up with make sure they dont have that stupid screw on tip. Those things caused me no end of grief...vibrating loose and misfiring.
 

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Discussion Starter · #6 ·
Thanks for your input guys!

I was experiencing a miss under heavy acceleration, though it was irregular, so my plan was to change the plugs and wires as they were old and needed to be done anyways, then begin a process of diagnosis following Naj's guidance.

I ended up with Champion RN11YC plugs and an Autocrap wire set as these were all cheap and readily available (fully prepared to return the wires if I experienced issues).

After the swap, I took the Lancer out for some testing, running at various RPM's, throttle position, and boost psi and I experienced zero misfires whatsoever. This is tuned down to 11psi. I still plan to diagnose my entire ignition system to ensure everything is working as it should be, but I also feel comfortable to start bumping the boost up gradually to my normal 15psi. :thumb:
 

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I recall reading that platinum or iridium plugs are not ideal for forced induction engines, but I don't have a reference to back that up. Copper plugs are what I run; they're cheap and a better conductor than platinum or iridium. However, as aforementioned, they don't last as long, but with the cheaper price, and ease of which they can be changed on our engines, I don't mind.

Locally Champion RN11YC are not available; it jumps from RN12YC down to RN9YC which are a little too cold in my opinion. For this reason I use NGK V-Power copper plugs. The stock plug is a GR4, while the next coolest plug is a GR45 (NGK heat ranges are reversed from Champion, higher you go, colder the plug), but there is also a GR5 and GR55 available.

I run GR45 plugs, with NGK ignition wires (these are the premium OEM brand available locally). They're lifetime warranted, so I just swap them out every couple years. As NAJ said, the stock ignition system is very reliable and efficient; I don't see the need for 8mm or greater diameter wires when running stock (12-14 psig) boost.
 

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When it comes to plugs, options are wide. When someone says "platinum" plugs they're most likely referring to the particular brand that they used/tried, so don't go any broad sweeping opinions one way or another on "platinum" plugs. I have had negative experiences with "platinum" plugs myself, I think they were the Bosch ones, but now I use the autolite double platinums APP66 (or APP65) and they haven't given me any problems (I have 10 Daytonas with 2.2s and 2.5s, so I got some mileage under my belt with them).

As for Wires, I use the 8mm Taylors, I order them from Summit since they aren't stocked anywhere locally that I could find, and again, no problems. They hold up for quite a while also, when they get questionable, pull them out of the cap and and turn the prong around the other way and keep going. When they get questionable again clean the prongs off with a small wire wheel in a dremel and kepp on keepin' on. I've done this with stock coils and various aftermarket coils - coils are a different issue all-together....
 

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When it comes to plugs, options are wide. When someone says "platinum" plugs they're most likely referring to the particular brand that they used/tried, so don't go any broad sweeping opinions one way or another on "platinum" plugs.
I was referring to the actual construction. The issue (if memory serves me right) was that most precious metal plugs (platinum, iridium) have a fine wire electrode. This smaller electrode heats up quicker and runs hotter than a comparable copper plug for the same application and therefore is more susceptible to pre-ignition.
 

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I'm running a MSD Ignition Coil, NGK Racing Wires, NGK non-projector plugs, Also Premium Blue Streak Cap and Rotor:thumb:
 

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Single Platinum, Double Platinum and Iridium Tipped Plugs are OE on Numerous Engines/Manufacturers with Superchargers and Turbochargers.

GM/Subaru/Mercedes/Audi/Porsche, etc.

Again, I have been running them for over 20 years with no issues.
 

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It's good to have to change the plugs once in awhile with our AL heads.
Anti-Seize and they get changed every 2 years right before I go for State Inspection just because.
 

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since the dodge garage gets quoted so much around here, here's what he had to say on the subject:platinum spark plugs (Bosch, Autolight, etc...) They fall apart, opps! & Accel coils, any of them. Platinum plugs were primarily developed for long installed life, no high performance.

SplitFire plugs don't seem to have any effect on our cars at all, except your wallet is $20 lighter of course,,, I have heard reports of them slowing down cars with the fast burn head because they disrupt the swirl effect of the cylinder head. Ford engineers did a study of them a few years back and came to the conclusion that Splitfire had found way to get the public to pay for plugs at $5 a pop.


Bracket racer Angelo Taylor writes in...

...I NEVER had luck with Splitfires or Bosch Platinums...
...nothing wrong with stock Champions.

I have to agree with Angelo on this- My Reliant throws down 10 second passes using Champions with no problems.
apparently, he hadn't worked on any thunderbird super coupes back in the day, they came with platinum plugs from ford for longevity and simply because they are a bitch to change lol.
 

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since the dodge garage gets quoted so much around here, here's what he had to say on the subject:platinum spark plugs (Bosch, Autolight, etc...) They fall apart, opps! & Accel coils, any of them. Platinum plugs were primarily developed for long installed life, no high performance.
That's funny because as I said, no problems with Platinum plugs in over 20 years and I have been using an Accel Coil for 22 years with no issues.
Only issue I had was when I replaced the first 17 year old Accel Coil in 2010 only because it was 17 years old.
Replaced it with a SMP coil and it died 6 months later on the starting line in the 3rd round of eliminations.
Replaced that with another Accel and have had no issues since but hey...
What do I know, I'm just a guy and real life experience means nothing so...

To each their own, use what you like and whatever helps you sleep at night.
Lesson here for me is...
Never get involved in a thread asking which spark plugs, oil, etc are the best, it just opens a can of worms.
 

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i feel the same way, i use copper core plugs simply because they are cheap and work well, i did use an accel coil, noticed the other day it was leaking oil out of it (less then 1000 miles old) but it still was working just fine, i changed it just on the thought of it isnt supposed to leak out of the center post and now that i seen it, it will deff fail when i'm 3 +hours from home or the shop, in the rain at night when i'm running late already.
 

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Yeah, it was the Bosch platinums I used, never any luck with them, always end up changing them out for coppers...cheap, and no reason not to change them every 30k miles or so. But more important is to get a plug without that screw on cap...I have a big thing against those.
 

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As for the actual construction of the Autolie double platinums, the ground electrode has a small pad on itwhich I assume is platinum, the center electrode appears to be one piece in that it's not clear if there is a seperate platinum piece at the tip. Maybe just the tip is platinum and they're machined during construction so you don't see any difference, or maybe the whole center electrode is platinum - my money is on the former.
 

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Single Platinum, Double Platinum and Iridium Tipped Plugs are OE on Numerous Engines/Manufacturers with Superchargers and Turbochargers.

GM/Subaru/Mercedes/Audi/Porsche, etc.

Again, I have been running them for over 20 years with no issues.
Not contesting that they don't work. For what it's worth, the Champion plugs you listed have a "fat", normal sized electrode, so the concern about the fine wire tip heating up quickly is a moot point. We all appreciate your input. :thumb:

Yeah, it was the Bosch platinums I used, never any luck with them, always end up changing them out for coppers...cheap, and no reason not to change them every 30k miles or so. But more important is to get a plug without that screw on cap...I have a big thing against those.
Also not a fan of Bosch spark plugs.

....the ground electrode has a small pad on itwhich I assume is platinum, the center electrode appears to be one piece...
This is correct; the double platinum plugs have a solid platinum electrode with a platinum pad on the grounding strap.
 

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The only reason IMO for ever using a Double platinum Plug is if you have a "Waste Spark" Ignition System.

On a standard ignition system(current flow starts at the coil and grounds at the plug) like ours only the Center Electrode wears, not the outer so a Single Platinum is all that is needed to prolong plug life and maintain efficiency.
On a "Waste Spark" Ignition 1/2 of the Cylinders are negative firing, meaning that current flow starts at the plug and grounds in the coil.
On those cylinders it is the "Outer" Electrode that wears, not the center.

As far as Copper...
Yes, Copper is a better conductor than Platinum or Iridium but it is a soft metal.
In 15 years at Jeep I saw what Copper Plugs with 20-25K look like.
Center electrode is worn to nothing with an extremely widened gap and in most cases setting a Cylinder Misfire Code.
So the question is...
At what point did the plug wear enough that it started raising KV requirements and start affecting performance, fuel economy and emissions?
 
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