Engine temp. once again, now ethanol
 

This is quite discussed topic, but I still have few questions to be sure. I'm still trying to find ways to increase fuel efficiency on E85 conversion.

Changing to hotter radiator thermostat is good for fuel efficiency, as we(or you, I just read what's been up there earlier) know. As E85 is over 104 octanes, I don't believe that there is going to be any knocking issues. I've even planned to change to iridium tt spark plugs and goin to run slighly lean side.Engine to be "modified" is Toyota 2sz-fe, compression ratio is 11.0:1.

While A to B to A is only way to have absolute correct answer, I wouldn't like to end up A to blow a coolant hose or even A to B to melt a piston, I'm placing these questions.

1. Engine temperature and ability to run lean are againts each other somehow, while both increase change of knockig and running lean is already running hotter. Which is better for FE, any estimations?

2. How much is safe coolant pressure for stock system, any experiments? Stock radiator cap is 0.9bar with 82 celsius thermostat, I could go higher if it's safe and could find parts. But really don't want to blow any hoses, it's goin to be a real mess.

Bonus question is of course that if I'm even on a right line with these speculations!

Japanese automakers tend to be quite conservative when it comes to flexfuel engines here in Brazil, not going so extreme when it comes to changing the compression ratio and operating temperatures, and AFAIK only Honda and Yamaha had some negligible experiences with dedicated-ethanol engines for motorcycles in the '80s. OTOH resorting to a higher-temperature thermostat was still a common practice for aftermarket flexfuel conversions in Brazil until a few years ago. A good-quality hose and other parts of the cooling system may not suffer any damage, even though I guess nowdays the NOx issue may prevent automakers from switching to a higher coolant temperature on the newer flexfuels, nowadays that sequential fuel injection allows a more accurate engine temperature control too.

On a sidenote, around 13 years ago it was still quite common to simply replace the thermostat on some cars, even though their engines eventually didn't have a flexfuel trim neither from the factory or from some aftermarket provider, and run them on ethanol. For instance the Ford Duratec 2.3L engine, being fitted with the thermostat of a 1.6L derivative of the Renault Cléon-Fonte engine made by Ford under license in Brazil which had dedicated-ethanol versions.