Systems and methods are provided for performing ethane steam cracking at elevated coil inlet pressures and/or elevated coil outlet pressures in small diameter furnace coils. Instead of performing steam cracking of ethane at a coil outlet pressure of ˜22 psig or less (˜150 kPa-g or less), the steam cracking of ethane can be performed in small diameter furnace coils at a coil outlet pressure of 30 psig to 75 psig (˜200 kPa-g to ˜520 kPa-g), or 40 psig to 75 psig (˜270 kPa-g to ˜520 kPa-g). In order to achieve such higher coil outlet pressures, a correspondingly higher coil inlet pressure can also be used, such as a pressure of 45 psig (˜310 kPa-g) or more, or 50 psig (˜340 kPa-g) or more.