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[morghen]

Pulled the cover to check the valve play and with a cold engine measured 0.2mm intakes and 0.45 exhausts. I need to re-check them with a warm engine after i put everything back together.

Anyway, on to the sparkplugs. Not much before the 5000 trip i replaced the plugs with colder Bosch W2CS plugs, these are really cold plugs. The reason i used these was to try to improve the detonation amount.

From left to right, cyl1,2,3,4.
As visible, the heat range is just right so i'm happy with that.
Ceramic looks uncracked, fairly clean and brownish so i'm concluding no massive detonation occured.
Gap is still 0.6mm so no issue with the ignition system, no premature wear on the plugs.

However there is quite a bit of deposit on the rings..i did not expect that much.
And if one looks closer at the ground strap there seems to be quite a bit of silver specs..less on the 1st and second cyls and more on the 3rd and 4th.
Those silver specs are signs of detonation...the silver specs are bits of aluminium that fly off the pistons. So i need to improve the cooling of the head as well as the charge temperature. The 937 DITC can be felt aggressivly pulling back timing especially on warmer days with more than 50% open TB.
Obviously i only ran minimum 98RON gas and when i found it Shell Race 105. I think the issue is all thermal.
Opinions?




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