Nov 17, 2008 · The PT6 burns more fuel for the same power. The TPE331 is a better engine but does cost more at overhaul time & doesn’t like sloppy mechanics/mx. The PT6 is bullet proof, simple for any mechanic, cheaper at over haul but burns more fuel/HP. Ditto 185Driver… The TPE331 is more efficient than the PT6. PT6A Engine Upgrade Program. StandardAero presents an innovative alternative for PT6A operators with its Engine Upgrade Program. Upgrading your PT6A engines provides you with the benefits of Pratt & Whitney Canada’s latest technology - with improved compressor efficiency and a cooler running hot section, these upgrades lower direct operating costs and provide higher aircraft resale values.