That is a bit optimistic :-)

The potential energy per gram of mass is much lower than for coal burning in Earth's atmosphere -- worse, the kinetics are so sluggish that you would need a very large vessel with good insulation to build up a useful temperature differential.

You'd also need to concentrate perchlorates from the Martian soil before they would sustain combustion with methane. Assuming that was done, though, perchlorates plus hydrocarbons will combust with vigor.