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+--- Thread: W124 build (/showthread.php?tid=6478)
RE: W124 build - MFSuper90 - 04-24-2018
Hate to hear that it lost a PC. You should hop over on competition diesel sometime. Lots of high performance diesel knowledge there.
Pump timing atdc doesn’t make any sense to me. In a perfect scenario you would inject at tdc, but you have to account for the time it takes to inject the fuel, and there are a lot of variables there.
On some of our high performance tractor pulling engines timing varies between 20-50 btdc. The more rpm, the more timing it needs. But the bigger the pump, the faster the injection rate, therefore not as much timing is needed. Stock spec is normally around 12-15btdc. The one I’m currently messing with will use a 13mm p-pump capable of 1100cc. It will be dialed back to around 500cc probably. I am going to start at 32* of timing, and probably go up from there if need be. This is all direct injection engines, but basic concepts still apply
RE: W124 build - atypicalguy - 05-15-2018
(04-24-2018, 01:21 PM)whipplem104 Well rough bit finally hit. Prechamber dropped the tip off and damaged the piston and bent a valve but upon disassembly all the rods appear to be bent. Slight scuffing on the cylinders from side load. Overall I am super impressed it has lasted this long. Even though the miles have not been many. All of them have been at near fulll throttle. So I was thinking about 3-4 tanks of fuel. So around a 800-1000 miles of full tilt. Either dyno testing or track time. And quite a few around the blocks.
Looking at solutions for the problems. Maybe redo piston rod profile and looking into some options on prechambers from coating to new design.
I think you may just want to lower the compression to reduce the peak cylinder pressure. 21:1 is a lot to multiply 40psi by. Maybe just buy some slightly shorter autoverdi rods or similar; lots of places seem to sell them. Perhaps shoot for 16 or 17 to 1.
Seems like timing is pretty important on the whole peak pressure thing also. Can't recall where you were set on the start of injection with your pump.
And aren't the prechamber failures usually due to leaky injectors?
RE: W124 build - atypicalguy - 10-07-2018
Did you ever stick this thing back together?
RE: W124 build - whipplem104 - 10-09-2018
Not yet. It is going to be taken apart further and sent to get the body work done and the engine is going to be rebuilt. Just other stuff on my plate for now.