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BruceW

Well Known Member
(sorry if this has been covered. Quick search did not find an easy answer. Direct me if there is a thread on this)

Have Lightspeed Plasma II on an Aerosport IO-360. Standard compression.
Looking to replace plugs. Have been running #24 (hot) plugs, like what came with it.
Wondering about using #27 (medium) plugs. And what the difference is? (other than the number 3)

The Lightspeed order page shows #24 plugs "used on lower to standard compression engines", and #27 for "used on standard to higher compression engines". So looks like I could use either on my standard compression IO-360.

Responses, or direction to info source, appreciated.
Merry Christmas.
 
I have an IO-360-A1B6, 8.7:1 CR Pistons (stock) with Dual Plasma III ignitions.

I had over 150 hours of trouble free operation with the Denso IK27's.

I just swapped to NGK BR8EIX, stock #6747, because I wanted to have a little warmer plug. I have also had good performance with this plug and Lightspeed Plasma III in a previous IO-360-A1B6 engine.

The NGK has a smaller gap and larger electrode than the Denso which should create less stress (lower resistance) on the coils.

And they're cheaper :)
 
been using the Denso 5391 IWM24 since beginning of 2020, e.g. some 200+ hours later, all good. Starting, performance, consumption and Ts all in line :)
Dual Plasma II, carbed O-360.

Previous owner mentioned a much better running engine jumping from 27 to 24 grade, can’t tell for sure since I only went from 2 electrodes to iridium...
 
Looks like two out of three dentists prefer hotter plugs on standard compression Lycomings. Thanks.
 
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