Im trying to calculate how hot the gas inside my exhaust pipe is. I have several numbers and a calculation on how to find heat transfer, but no way of finding inside temperature if i don't already know it. Length= 0.5m k (heat coefficient for stainless steel)= 25 Internal Diameter= 73.2mm Outside Diameter= 76.2mm Outside Temperature= 206°C Inside Temperature= ? I managed to get the inside temperature at the exhaust exit which gave me... Inside Temperature= 171°C Outside Temperature= 90°C With that I was able to use the formula: Heat Transfer = ((2 * pi * k * L)/(Ln(Outside Dia/Inside Dia)) * (Inside Temp - Outside Temp) This gave me a heat transfer figure of 159,043.5W Whether any of that helps me figure out the temperature further up the exhaust pipe I have no idea. Especially considering I don't know the internal temperature of the gas at that section of piping. Anyone got any ideas?