the 3.6 he is referring to it the AMG c36 m104. it uses a modified OM603 3.5L crank with a stroke of 92.4mm. with the stock bore of a 103 it will get you around 3.5L the c36 is also bored out slightly to get 3.6 however this makes the head gasket a very short lived thing. i would seriously consider a 104 over a 103 due to the much better head flows of a 4 valve engine. that being said, as you stated this is just for the hell of it to see what can be done. for cams i would look at Dbilas Dynamic and Cat Cams they both stock grinds for 104's and 103's from mild to extreme. if you want to go all out start thinking of things like long tube equal length stepped bore headers, and ITB's. it all comes down to getting air in and out of the engine as fast and easily as possible.

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1985 300D om617: 8mm M pump 175cc 5200rpm, holset he221w @ 30psi, large A2W ic, compounds on the way.
KD9AFT
A&P