New SE Plugs

[baggerdad]

Mike, I've been following a thread on NGK Iridiums and Ion Sensing on the V-Twin Forum.

http://www.v-twinforum.com/forums/twin-cam-96-engine-technical-discussion/118391-ngk-iridium-spark-plugs-9.html
http://www.v-twinforum.com/forums/1665887-post119.html
http://www.v-twinforum.com/forums/1665889-post120.html

I'd like to try one of the new SE Plugs primarily for possibly improved firing Performance and starting. I run NGK Iridiums now and do not throw any codes. Just thinking the SE plugs were designed specifically for Harley and addresses Ion sensing.

Screamin' Eagle® Street Performance Spark Plug - High Compression Applications P/N 32186-10
http://www.harley-davidson.com/gma/gma_product.jsp?PRODUCT%3C%3Eprd_id=84552444877415 5&FOLDER%3C%3Efolder_id=2534374302491575&ASSORTMENT%3C%3East_id=2534374302491575&bmUID=1251693890533&bmLocale=en_US

Screamin' Eagle® Street Performance Spark Plug - Stock Compression Applications - P/N 32192-10
http://www.harley-davidson.com/gma/gma_product.jsp?PRODUCT%3C%3Eprd_id=84552444877415 5&FOLDER%3C%3Efolder_id=2534374302491575&ASSORTMENT%3C%3East_id=2534374302491575&bmUID=1251693890533&bmLocale=en_US

Do you know if the new SE plugs have been cleared for Ion sensing. My engine is not stock.
It registers 210 ccp. It's a 97" Axtell build with Baisley Super Stock Heads. It has been tuned using the TTS, with stock plugs and cables installed. It does not ping or detonate under load.

The marketing says the SE plugs are double platinum coated, are the electrodes Iridium?
And what makes the SE High Compression plug, is it a colder plug than the SE stock compression plug?

In regards to Ion sensing, is that only for stock engines?
Does building a high compression performance motor negate the concern for using a stock plug for Ion sensing purposes?

[Mike]

In the most simplistic terms, ION sensing is no more than reading the amount of resistance that must be overcome to fire the plug. This can be measured by the residual amount of ION's after fireing the plug. This can change with plug gap, plug age and (most importantly for us) cylinder pressure. The higher the cylinder pressure the higher the resistance the plug "sees". This is why high compression motors tend to give false knock detection. To activate an engine code requires parameters to be set (I.E. a high and low resistance value) for the ECM. These tend to be for stock engines but experiance seems to indicate they are wide enough for most SE engine builds (which tend to stay below 11:1 compression). Even HD will suggest that Knock Control be turned off for compression ratio's above 10.5 (more accurately, the dynamic cylinder pressures associated with the compression/cams/motor size/chamber volume/piston shape-area/rpms/etc.).

The actual "ION Sensing" technology is much more complex than this, but when thought of in these terms, we can understand what affect our changes have.

Our experiance (and testing on Pro Stock bikes) has shown that plug alone make little difference to power output when in good shape or new and proper tuning. Iridium and other rare metal plugs tend to last longer and therefore maintain their performance (and engine performance) over longer periods of time. Some also have higher tolerance for fouling which can be an aid in high compression motors.

The new SE plugs are rated for ION sensing.