I have a 94 Honda Civic with Si motor. I blew my radiator and replaced it but now the lower hose is cold. I believe my thermostat is gone now. I went to autozone but they have different temperature thermostat. Which one is for my Si motor. Thank you.

 

which Si motor? a civic? prelude? crx? i'll assume you mean a d16z6 and say the stock thermostat is 180*, so get that.

 

mine has a 180 degree in my b16. no problems. once it gets near halfway on your temp gauge it will open. it scared me at first too but it wont hurt anything i promise (hundreds and hundreds of miles have confirmed this)

 

call honda, ask them, get the oem temp... or just get the oem part.
also need more info? what type of motor single, dohc?? what temps do the offer? 180 seems ok to me. my buddy has one is is b16 with no problems for about a year.

 

Your fan should kick on at 190 so 180 is fine. I run a 170 spoon thermal sending unit and spoon 170 thermostat.