On Fri, 8 Jan 2021 00:05:24 +1100, Xeno wrote:

> The lower temperature thermostat would run the engine cooler by 15
> degrees and that would increase intake air *density* resulting in more
> power. For a performance application, the 160 thermostat might even gain
> a little more power - for the same reason. Note too, running the engine
> cooler means you have more leeway in the risk of auto-ignition of the
> end gas meaning less risk of detonation. You can get away with either
> more spark advance and a higher compression ratio.

Hi Xeno,

I do NOT profess to be an expert in this topic, not in the least, so be
patient with me if I state what seems obvious & logical to me but which
might not be the case in reality (for today's engines).

The thermostat, as I was taught way back in the early sixties, opens up
_once_ (in general), and stays open for the duration (until the engine
shuts down).

In fact, once an engine is "warmed up", I was taught you could completely
remove the thermostat, and you couldn't tell, from the outside or from any
measurement parameter, that the thermostat wasn't even there anymore.

At least that was way back when...

Fast forward to today and emissions controls, I understand that today's
thermostats may be much more finely mapped such that they might open up a
few times during a typical drive; but do they?

If they do, then my comments below are moot, as the "lower temperature
mapped thermostat" could perhaps maybe affect the engine temperature (if
it's constantly in the never ending process of opening and closing and
restricting coolant flow).

But if the thermostat opens only once (given an engine runs hotter than the
thermostat set temperature), then wouldn't a lower temperature thermostat
simply mean that it opens once, but at a cooler temperature than before?