this is a cross post from STD for anyone interested in a high power OM617 and what goes into building one Hello i don't post a great deal here. however i have been working slowly on a project i have had in mind for a bit. i have a 85 300D w123 that i have been tinkering with for about a year now. my goal is around 300 HP with some reliability. i am aware that the easy way is to go with an OM606 however that has been done before. very few people have taken the 617 to its limit it seems and i enjoy a good challenge. i also enjoy designing my own systems and parts. So far i have maxed out the stock pump and re-timed the pump to 28* along with reamed and chamfered pre-chambers and increased the boost to ~14 pisg. i then got a new head and aggressively ported it till the port walls were around .150" as verified by ultrasound. the new head is waiting to go on till i can re-cut the valves and seats also need a tiny bit of port geometry smoothing still. all this is along with a HE221W i got and a W115 manifold thats on the way. also trying to find a shop that can calibrate AAZ two stage injectors with DN0SD315's. the long term plan is to get a compound turbo setup running a HE211W or HE200WG as the HP and either a HX35 or 40 as the LP. i am running a rigged water methanol system from the washer bottle right now and i am intending to replace that with a true high pressure injection system. also looking into getting a set of rods made for the engine but thats gonna cost a great deal so its far down the list. also investigating thermal barrier coating companies about the pistons and the pre-chambers. theres a great deal of other ideas too that i intent to explore. the max rpm capability of the engine is a question i am wondering about. considered buying a junkyard tired engine and pulling the high idle governor from the pump than running it in 500 rpm increases followed by compression tests to find the rapid degradation point or just see when the rods go for a walk. pictures to come as i can host them.

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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