What Padfoote said. I'm a fan of Performance engines, if you have a lot of redstone, glowstone or, um, blaze powder I think, to make it produce twice as much as a gasoline engine.
Also, you can do yourself and always keep an industrial coil or two charged.
For instance, you can charge the entry level industrial coil via a few weak steam engines while you're off mining. Then use it for a good burst of output (1MW) when you want to do some quicker work with the Extractor or something.
Just be careful as they explode when they go over their max limit. A comparator can be used to monitor it and cut off the power supply (clutch) when it reaches 90%.