here are my operating parameters with a s195 idi changfa
burning 15/40 low emission diesel oil as fuel
the coolant temp is controlled and operates between 205 and 214 degree's F
the head temperature averages ~238 degree's F
the engine is 20 to 1 compression from the factory
the exhaust temperature as measured with an infrared non contact thermometer runs
at 640 degrees F at approx 2 inches out of the exhaust port at the outside of the first elbow (the hottest part)
the output from the genhead will maintain 7.5 kwatt resistive output, and also another
couple hundred watts for the belt drives, another 130watts for the coolant pump and fan, and approx another 100 watts for field excitation and starter battery charging via one of the twin 555 alternators, for a total of a bit over 8kwatts output.
the exhaust burns cleanly, with no smoke and a bit of rack left, the engine will maintain this steady state operation for an hour or as long as one wants to run the test.
the only failures i had were failed head gskts at this load level, however i have rectified that issue with aftermarket gaskets from gskts to go.
i have had the head off after such runs on wmo and found there to be no more carbon than there is after running straight pump diesel.
the engine will start on straight motor oil, however it does smoke for approx 30-45 seconds then clears right up,
the carbon residue i have found on the piston and in the prechamber (the changfa has a removable hot plug) is soft and easily removed with a thumbnail.
now i have not amassed a thousand hours of testing however, i am convinced that if i were to provide some form of water mist injection periodically or propane/natgas fumigation the soft carbon would be easily cleared before it had a chance to harden and be heated to the point of ash formation.
i have never found any ash after such a run on motor oil.
now we might prematurely conclude all sorts of things, probably be wrong more times than not making hasty conclusion, however
i do think there is evidence that motor oil can be burned successfully and without engine damage in a changfa and perhaps other engines under certain conditions.
i really believe that carbon removal is key, before it has a chance to harden under heat and constant pressure and be converted to ash. having higher compression ratios might help as would higher coolant temperatures.
btw the engine runs smoother makes less noise (noticeably less diesel knock), makes more power (approx 10%) and has improved BSFC (5% better) running on oil vs pump diesel.
all indications with this engine ran under these conditions is the use of wmo as fuel
looks promising, however it might be prudent to follow controlled decarbon by manual or gaseous fumigation or water mist injection.
another thing comes to mind, i have torn down many old gas engine's that were using massive amounts of lube oil, the kind that foul plugs badly and smoke like a freight train. i have also seen copious amounts of ash deposits (white caked up deposits) on spark plug electrodes/tips and in the combustion chambers. relatively large amount of ash and carbon buildup,,, and also have found the cylinders to be in remarkably good shape on some of these engines as well.
those engines that seem to maintain cylinder condition best are those with high nickel content castiron and those that do worst are those with low nickel content cast.
this might lead one to conclude that the ash deposits "if" abrasive, are much harder on
low nickel cast cylinders (cheaper engines) and it would appear the abrasive nature of the ash product is not hard enough to effect the harder nickel cast cylinders.
i think it is time to get my hands on some of the ash, and do some testing to see just how abrasive it really is, and what its effects are against low alloy cast iron vs high nickel content cast iron vs induction hardened liners.
i am going to go way out on a limb and place a bet,
my bet is the ash is not hard enough to touch the surface of a nickel iron block and even less so with an induction hardened liner.
failing that one, my next bet would be that the carbon left behind from using wmo as fuel is no where near hard enough to even touch a hard liner or nickel cast iron cylinder.
time to do some research and testing
place your bets boys!
bob g