How does the air get heated and expand inside the turbo? What source creates this heat?[email protected] said:But the point we've all been trying to make, is that simple volume is not enough. The heat expansion is required to increase the impelling force, essentially a volume increase, but not in so few words. Besides as Mike K. said other things are at work in the turbine chamber. A turbo is spinning at supersonic speeds in a highly confined area, things tend to work a bit differently.