Lower CHTs with Fine Wire Plugs?

Fearless Tower

Fearless Tower

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Anyone else using iridium or fine wire spark plugs? I swapped out my massives for iridium plugs in the Waco (W670) at this year's annual and have noticed that my CHT is running around 15C lower since. I'm curious if anyone else has noticed such a benefit?
 
Fearless Tower said:
Anyone else using iridium or fine wire spark plugs? I swapped out my massives for iridium plugs in the Waco (W670) at this year's annual and have noticed that my CHT is running around 15C lower since. I'm curious if anyone else has noticed such a benefit?
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I never noticed a difference besides what they cost but that doesn't mean anything. Sounds like they work for your application. Are they the same heat range as the ME you replaced?
 
My IO-540 runs about 20 degrees further LOP. No noticeable difference in my CHT's.
 
They run cooler because of the weight reduction in your wallet.
 
What is the nature of your CHT thermocouples? Spark plug gasket ones, by any chance?
 
Let me know what the difference is when the new plugs are the same age as the old ones you removed. No I don't know if there will be any, but the new ones probably have new copper gaskets which will transfer heat to the head better.

But if you are using gasket type thermocouples it shouldn't make any difference.
 
are you certain nothing else changed?
 
Tom-D said:
Let me know what the difference is when the new plugs are the same age as the old ones you removed. No I don't know if there will be any, but the new ones probably have new copper gaskets which will transfer heat to the head better.

But if you are using gasket type thermocouples it shouldn't make any difference.
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The old plugs were less than two years old. The engine has about 60-70 SMOH in two years.

The only other thing we did at the same time was change from straight mineral oil to ashless dispersant. Running Aero Shell 100.
 
Fearless Tower said:
The old plugs were less than two years old. The engine has about 60-70 SMOH in two years.

The only other thing we did at the same time was change from straight mineral oil to ashless dispersant. Running Aero Shell 100.
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Don't know what to tell ya.
 
Fearless Tower said:
Anyone else using iridium or fine wire spark plugs? I swapped out my massives for iridium plugs in the Waco (W670) at this year's annual and have noticed that my CHT is running around 15C lower since. I'm curious if anyone else has noticed such a benefit?
Click to expand...
Yes, I went from champion massives to tempest fine wires and noticed about 10-15 Deg C drop on CHTS.

What I cannot tell you is if it was due to 30% of the champions having excessive resistance and now I can run smoother further LOP which equates to the cooler CHT or if it was just the better fuel burn.

But my engine does run cooler now, about 300 310 DegF CHT's LOP with oat at 70 DegF at 4-5k ALT.
 
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