I live in California. My car is stock except for 2-chamber flowmaster. If I were to put a 180 deg. thermostat and a lower fan switch, would my car still pass emissions?

Akshay
89 RS T-5

 

Depends. In most cases when the emission test is performed the engine will still run hotter than the 180 degrees the stat is rated at. It will in most cases pass without a problem assuming all else is OK. The problem comes in when you start playing around with the fans and getting the average operating temp below 195 or so. I have tried all different setups with my 89 and I have found that the best operating temp is the stock 195. You will get TONS of discussion on this subject here and other places but truth is that the engine is most efficient when it's average operating temp is around 200 degrees. Without altering the fan control the engine will still reach around 220 before the fan energizes so most likely during a test you should be fine. I would not go lower than a 180 however because you will then see a difference in fuel economy and will most likely generate more crap out of the pipe.