By this point reliability had improved with the mean time between overhauls at 3,500 hours and specific fuel consumption in the order of 0.4 lb/hp/hour (243 g/kWh, giving it a 34% fuel efficiency). Engines in use now are limited to 52 inHg (180 kPa) manifold pressure, being 2,880 horsepower (2,150 kW) with 100/130 octane fuel (or 100LL) instead of the 59.5 inHg (201 kPa) and 3,400 horsepower (2,500 kW) possible with 115/145, or better, octane fuels, which are no longer available since many formulations are toxic.