[livewire516]

TLDR; this might be obvious to folk. It just seems like a well-tuned water/methanol injection system not only allows you to run leaner, advance timing, but also allow hotter air-intake temps, and tolerate a higher coolant temp without damage to the valve-train, before causing knock. Cooler exhaust temps means less waste heat. Higher tolerable operating temperatures means less need to waste heat in the form of radiator cooling. Convention says w/m inj., isn't worthwhile until you're playing with really high compression or power-adders like forced-induction or nitrous - but it seems like a lot of things ecomodders want to do are ultimately limited by engine temp/knock/fouling emissions.

I recently read some journal articles about barriers to improved efficiency in ICE engines. A good case was made that the main reason thermal efficiency is so low, is because the valve-train materials are the weakest link. Otherwise, most other components could be made to operate at higher temperatures.

Another weak link is the risk of pre-ignition/knock due to 'hot spots' somewhere in the combustion chamber. I won't get into the supposed 'it cleans your engine' properties of water/methanol injection, but deposits within the combustion chamber is one cause of such hot spots.

It seems as though water/methanol injection has a lot more potential to improve efficiency that it seems the community has exploited. It's cylinder head temperature that contributes most to triggering the thermostat, causing the cooling system to bleed off thermal energy. Exhaust temp is another source of heat loss. Basically, water/methanol injection helps to limit the temperature of the combustion chamber...where we need cooling most to prevent detonation and valve damage.

With a well-tuned water/methanol injection system, we should be able to tolerate higher operating temperatures. If I recall correctly, GM tried cooling the cylinder heads first in their Gen II small block V8s, but reverted to block-first cooling in the Gen III, because the temperature gradient/rate of change of cooling the heads first was too great. My understanding is that coolant channels in the block have gotten smaller over the decades. And in vehicles where the weight penalty is tolerable, the industry seems to be in no rush to go from cast iron blocks to aluminum. Cost aside, I can't help but think this is at least in part of it's mass and thermal conductivity of cast iron blocks don't present much of limit to cooling. If anything, it's properties of a heat sink help to 'pre-heat' coolant to keep temp fluctuation from stressing the cylinder heads.

I'd love to hear people's thoughts - I'm not planning on water/methanol injection for any of my vehicles. At least not anytime soon (if I did, it would be tinkering for its own sake). I hope any discussion could be more theoretical than practical