TDI engines have excellent life with less head issues than idi (cracking etc). They have been used in lorries for years and the vw tdi as well as other older engines (Rover Perkins Prima 2.0di diesel from 1989 on) that used di have had excellent reliability. They often have a useful side effect of contaminating the oil far less as combustion is kept central making for better oil life/less wear. I took a Montego up to 225k miles with no descernable wear anywhere, when I scrapped the vehicle due to rottern body.
Anyhow that's an aside a little, there is NO WAY in any circumstances that the pre-cup walls can heat the air. Energy ALWAYS travels from Hot > Cold, thus the colder walls will always warm up by heat removed from the air inside. Injector heating isn't an issue as it's screwed into the head and the ceramic coating won't affect that. Normally so much heat escapes into the head that water cooling is needed to avoid warping etc, even with the ceramic coating the engine will still reach temperature so heat directed to the injector should be much the same. Thermostat opening should be less as there should be less need to use the radiator due to heat kept in the chamber more. Even if one presumes that the chamber can heat the air before ignition (even though it's hot enough to self ignite diesel, which is way hotter than the temperature of a head surface) that heat would COME from the temperature of the burn, which is the same thing as robbing peter to pay paul. I think we need to get away from any idea that the pre-comp chamber can in any way heat the air in it due to a) it would need to be 700+c or thereabouts, which I put to the group it isn't.
b) even if conditions exist where it was proven that it is hotter than the air/combustion in the chamber, it's 'heat' isn't free, it's taken from combustion temperature. There are no glow plugs stuffed all over the head heating it, the heat is sapped out of heat that should be contributing to combustion pressure - ie power and efficiency!
I have been on a top fuel board where all the top teams use ceramic coating to increase power. another way of looking at it is to say make the same power, but with slightly less fuel. I can't fault the theory, the quality and efficiency of coatings and the number of coatings etc would make a difference, as would over swirling (if that's possible?) due to higher temp sustained in the chamber. I'm certainly convinced there are gains and it's a 'good thing' to coat, how much gains and if it's worth it is another matter. Subaru and top fuel engine builders, among others, think it is. Very little in the motor world is devoted to serious persuit of mpg but I feel it could have application there.
There has to be other longevity benifits, particularly in protecting the head from heat and the crown of the piston, those of you building heavy turbo motors take note ;-)
Apparently 'over swirling' is possible as it encourages more gas to be cooled from the chamber sides and reduces the burn quality.The VW swirl chamber is based on a Ricardo patent AFAIK from at least 60 years ago and in the 50's was regarded as one of the best of the IDI's efficiency wise.
Surely what makes an engine do work, is not the flames from the fuel but it is just a matter of heat... Extra heat expanding a particular volume of air. So arguably an infra red lightbulb could do the same thing.
Initially I couldn't see how the swirl chamber could heat the air; but I guess it can whilst air is cooler than the chamber. But what is the temp of the chamber walls? what with the coolant trying to suck the heat out. Heat will of course go back out of the air as the compressing takes it beyond wall temp on its way up to 600 deg C. Fuel burning only raises it up another 300 deg C or so,
Where did the rapidly cooling walls get their heat from? Obviously it came from the previous 4 strokes or at least the power stroke. Thus in the continual process the present power stroke will be 'robbed' of heat for the next cycle.
Ceramic coating will reduce heat loss so the same coolant will be able to remove more of the heat that does pass (2/3 of non ceramic setup) and so there will be less heat returning to the air from the chamber walls but with a 1/3 more heat staying in the chamber that doesn't seem a problem. If peak air temp in the chamber is higher in the ceramic case then turning the fuel down should result in similar temperatures to original setup.
Reducing radiator size could help; or using pure antifreeze (which although it boils at a higher temperature actually has a lower SHC than water).
I don't like the idea of higher and higher injection pressures just seems like extra energy wasted and extra strain on the pump. Neccesary perhaps for absolute power but for economy not required. Somewhere I have a book that suggests that over atomisation can lead to poor burning. Perhaps its linked to times of lower injection volume where the droplets can get lost in the excess of air and slow the flame front...
However efficient these TDI engines appear; I'm not getting the vibes that they will be long life engines.,,,
Rant off