In the mid 90's a buddy of mine bought a drag sled, thinking he could trail ride it. If he tried to run just plain premium gas, every time he would let off the throttle from a wide open run it would blow the porcelain out of both plugs, if he ran 110 it would not happen. The few rides we went on prior to reducing the cr required pockets full of new plugs.

There is a hole lot of white on those plugs

Just converting bar into soomething we understand so we can follow.

10 bar = 145psi
13 bar = 188.5 psi

those numbers are correct 👍

delete

yep, looks lean to me. I have AEM uego lsu 4.2 cauge in both risers wich reads 12.6 at cruising, 12.8 at wot. Offcourse i was not looking for the a/f cauges when this happened, i was just installed a water pressure cauge to my cooling system and were looking for the water pressure.

European 98e 5% ethanol gas is what i use. Some claims it is similar to your 93 octane.

https://cimg7.ibsrv.net/gimg/www.off...add533e1e9.jpg
Engine is out of the boat. Very curious what i find when i bull the head of.

#1 and #7 look just very slightly on the rich side, but okay. Rest look good. The white on the porcelain is olay also. The porcelain can be one indicator of the correct (or incorrect) heat range of the plug. Jmo.

here's one article that explains some things. There's another i am trying to find that I've seen before that explains things pretty good as well.

http://www.4secondsflat.com/Spark_plug_reading.html

Attachment 577414

another good writeup

https://www.dragstuff.com/techarticl...ead-plugs.html