The whole thing with a colder t-stat is that it keeps the engine a little cooler, yes. But this also will make the PCM add fuel. Thus, your fuel economy will drop. And most of you say" So what, I want performance. And the colder t-stat makes my car run like a raped ape!" Again, I have to ask, do you realize why this is the case?
Most of the time, when someone installs a colder t-stat and they see a performance gain, it is because they had KR to start with. So the increased fuel takes away the KR and thus, their car feels faster. Which it is because it doesn't have KR taking away the timing. So now, you are running more timing than before you changed the t-stat, but also more fuel. So you have your performance back, but you are burning more fuel to compensate.
If you mod correctly, and don't have KR to start with, there is no reason for a colder t-stat. So sticking with a stock t-stat and a correctly modded car with no KR, you can run more timing with less fuel. This not only makes the car faster, but more efficient. So you can have both performance and great fuel economy.
There is a saying with old car guys: "Leaner is Meaner". Meaning the leaner a car is, the stronger and more performance it will have....of course to a point. But adding a cold t-stat is the complete reverse of this. Adding a colder t-stat adds fuel, thus decreasing the performance of a correctly modded engine. The only way a colder t-stat will make an engine run better is if it was modded incorrectly in the first place. Then the cold t-stat is just a band-aid to the actual problem, and does not fix anything.
. But no really, when I changed to a 180* stat I didn't notice a change in fuel economy at all. No doubt the colder stat will lower gas mileage, but the change in fuel economy will be so miniscule that most people won't notice a change at all. So in my eyes a 180* stat is totally worth it, even if the gains are minimal at least it's something.
