I haven't really thought about it before... What does everyone suggest to use? Do I need to go colder?... What brand? copper? platnium? iridium?
Plugs of choice?
- Thread starter supra90mkiii
- Start date
Does that mean that I could use NGK's meant for MKIV's?
Basically, I don't like Autolite. Personal preference is all, really.
Basically, I don't like Autolite. Personal preference is all, really.
JustAnotherVictim
Supramania Contributor
The reason copper plugs are recommended over iridium and platinum plugs is because copper dissipates heat better the other two metals. The cylinder temperatures of boosted engine is significantly higher than there N/A counter parts at WOT. This can result in the tip of the spark plug getting hot enough to cause pre-ignition, if the motor is ran for long periods at load. This is especially true with platinum and iridium. The heat is more prone to stay concentrated at the tip rather than dispersing through the rest of the core as with copper.
So if copper is such a great thermal conductor then why did car company’s switch away from them. Simple, longevity. A copper plug in an N/A( I emphasize the naturally aspirated part) will last 30,000 – 45,000 miles. Platinum will last 80,000 to 100,000 miles and iridium’s will last 120,000+ miles. And N/A motors don’t run in to the same issues with thermal conductivity that boosted motors do. So they lessen the service requirements of the motor in the public’s eye. Car company’s like this, so they switched.
What would I recommend? I say go with the coppers.
1. Because it really isn’t that hard to change them. Quit being lazy.
2. It gives you a chance to see how the inside of your engine is running. Learn to read plug colors
3. Peace of mind.
4. Platinum’s and iridium’s really offer no performance advantages over properly gaped copper, except for long life.
However there is nothing wrong with running platinum’s or iridium’s if you don’t:
1. Run high levels of boost.
2. Do long freeway pulls.
If you don’t do these things then you probably won’t run in to any problems with them. Still, I suggest running coppers as most people have noticed (including me) that our engines are happier on coppers. Plus it’s hard to knock the price.
*Iridum doesn’t suffer near as bad as there platinum counter parts from thermal conductivity. However you may still need to go a few heat ranges colder than there copper counterparts. Still $8 or $100 dollars. You pick.
** I also find it funny that Iridums tout a 1200 degree higher melting point than platinum, as one of the advantages. That melting point is 4449.2 degrees Fahrenheit. If it’s that hot in your engine, it is already gone. You’ll have a pile of molten metal with perfectly preserved spark plugs. Iridums also tout a 120,000+ mile life span however they recommend replacing them every 30,000 miles.
Taken from densos web site.
“Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.”
Got to love the fine print. So replace your $100 plugs every 30,000 miles, or replace your $8 copper plugs every 30,000 miles.
So if copper is such a great thermal conductor then why did car company’s switch away from them. Simple, longevity. A copper plug in an N/A( I emphasize the naturally aspirated part) will last 30,000 – 45,000 miles. Platinum will last 80,000 to 100,000 miles and iridium’s will last 120,000+ miles. And N/A motors don’t run in to the same issues with thermal conductivity that boosted motors do. So they lessen the service requirements of the motor in the public’s eye. Car company’s like this, so they switched.
What would I recommend? I say go with the coppers.
1. Because it really isn’t that hard to change them. Quit being lazy.
2. It gives you a chance to see how the inside of your engine is running. Learn to read plug colors
3. Peace of mind.
4. Platinum’s and iridium’s really offer no performance advantages over properly gaped copper, except for long life.
However there is nothing wrong with running platinum’s or iridium’s if you don’t:
1. Run high levels of boost.
2. Do long freeway pulls.
If you don’t do these things then you probably won’t run in to any problems with them. Still, I suggest running coppers as most people have noticed (including me) that our engines are happier on coppers. Plus it’s hard to knock the price.
*Iridum doesn’t suffer near as bad as there platinum counter parts from thermal conductivity. However you may still need to go a few heat ranges colder than there copper counterparts. Still $8 or $100 dollars. You pick.
** I also find it funny that Iridums tout a 1200 degree higher melting point than platinum, as one of the advantages. That melting point is 4449.2 degrees Fahrenheit. If it’s that hot in your engine, it is already gone. You’ll have a pile of molten metal with perfectly preserved spark plugs. Iridums also tout a 120,000+ mile life span however they recommend replacing them every 30,000 miles.
Taken from densos web site.
“Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.”
Got to love the fine print. So replace your $100 plugs every 30,000 miles, or replace your $8 copper plugs every 30,000 miles.
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Really interesting info Dirgle!
As a "test" I've just swapped out my irridiums for a set of coppers in the same heat range/maker as I've noticed a bit of low rpm fluffiness the last few runs!
(this shows up in it won't pull a high gear at low rpm smoothly)
When I pulled the IR's they were all even so the tune and distribution is good but they were a bit furry with fine deposits which would indicate to me they're overheating on long pulls.
I'll run the Coppers for a few weeks under the same conditions and see how they hold up!
As a "test" I've just swapped out my irridiums for a set of coppers in the same heat range/maker as I've noticed a bit of low rpm fluffiness the last few runs!
(this shows up in it won't pull a high gear at low rpm smoothly)
When I pulled the IR's they were all even so the tune and distribution is good but they were a bit furry with fine deposits which would indicate to me they're overheating on long pulls.
I'll run the Coppers for a few weeks under the same conditions and see how they hold up!
That's good info IJ.
What heat range are you running, and what gap do you have them set to?
I look forward to see what type of data you return.
What heat range are you running, and what gap do you have them set to?
I look forward to see what type of data you return.
Not to beat a dead horse, but NGK Iridiums are only $42 for me($6.99 each). Coppers are $9($1.50 each). This is at Pep Boys.
$42 @ 30,000 = $42 for 30,000 miles
$9 @ 3,000 = $90 for 30,000 miles
In the end it's actually cheaper to run the Iridium if you aren't racing. Although the extra piece of mind that comes from changing your copper plugs every oil change is better for some, others don't want to worry about spark plugs every other month.
I've been running NGK Iridium in the Supra for 8 months(10,000) now without any problems at stock boost. I do agree about coppers for higher boost or heavy racing though.
$42 @ 30,000 = $42 for 30,000 miles
$9 @ 3,000 = $90 for 30,000 miles
In the end it's actually cheaper to run the Iridium if you aren't racing. Although the extra piece of mind that comes from changing your copper plugs every oil change is better for some, others don't want to worry about spark plugs every other month.
I've been running NGK Iridium in the Supra for 8 months(10,000) now without any problems at stock boost. I do agree about coppers for higher boost or heavy racing though.
I told a lie...... :3d_frown: doh!IJ. said:
The IR's were gapped to 28 thou and I just pulled the Coppers to double check as I'd noticed some break up last night during a run and they were gapped to 40 thou!
Last trip to the Dyno we swapped the plugs out and my Tuner gapped them to suit the CDI, I just beadblasted them and dropped em to 28 so will see how it goes.
They were all even coloured so the distribution with my manifold is fine!
(would be more of a concern for me running a Carb and not multipoint injection)
Well that was interesting!
Nothing changed other than Plug Gap and it now lights the rear tires in 2nd at around the 5000 rpm mark idles smoother and feels crisper!
Nothing changed other than Plug Gap and it now lights the rear tires in 2nd at around the 5000 rpm mark idles smoother and feels crisper!
I have a n/a mkii with a jdm motor. i have new spark plug wires on the way. there Toyota Supra Magnecor Spark Plug Wires R-100 10mm
I was woundering which spark plugs would work best. i noticed some people saying copper.
I was woundering which spark plugs would work best. i noticed some people saying copper.
As noted, platinum and iridium offer no performance advantage except longer life. I'll spare you the lesson on plasma physics but if you use anything else the plugs will wear faster. Not a problem as long as you deal with it. This is due to the Supra using a DIS/waste spark system. Not only does each plug fire twice as much as it needs to but the polarity is opposite on every other plug, causing greater wear. It's the reason the car, N/A or turbo, came with platinum in the first place. For those who know GTAW theory it's the same as running electrode positive, with the same physics at work.
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For anyone thats interested you can cross reference any plug for your Supra or anyother car at sparkplugs.com. I personally only run Nippon Denso Irridium in everything even my dirt bikes.
Rick
Rick