Model diesels are found to produce more torque than glow engines of the same displacement, and are thought to get better fuel efficiency, because the same power is produced at a lower rpm, and in a smaller displacement engine. However, the specific power may not be significantly superior to a glow engine, due to the heavier construction needed to assure that the engine can withstand the much higher compression ratio, sometimes reaching 30:1. Diesels also run significantly quieter, due to the more rapid combustion, unlike two-stroke glow engines, in which combustion may still be occurring when the exhaust ports are uncovered, causing a significant amount of noise.