Running no stat, the water passes throw the radiator too fast, not disapating/exchanging heat transfer,.....so you could actualy run hotter,....or in some extreme cases you could run too cool, which isn't good for oil viscosity to properly lubricate and flow through out the engine,....if you feel you must run without a stat, there are "restrictor washers" avaliable, which basically look like a washer, you'll need to experiment with various sized orifices to acheive the desired running temp,....which should be around 190 degress IMHO,....if coolant flow/thermostat opening is a concern, drill a relief hole in the stats base before you install it, 1/16 up to 1/8, max 1/4" dia