Figure 1 http://outreach.phas.ubc.ca/phys420 /p420_08/Hiroko%20Nakahara /Pictures/heatEngine.jpg

In an engine, heat (Q-in) is taken from a heat source, then work is done, and heat (Q-out) leaves the system. This is shown in Figure 1 to the left. Figure 2 demonstrates this cycle on a pressure vs volume graph. When heat is added to the system, the pressure goes up. As work is done by the gas, the pressure goes down while the volume goes up. Then heat is taken out of the system so the volume goes back down. Finally, work is done on the gas so the pressure rises and the volume fall. This process repeats at a very fast pace. Monster Trucks are limited to a 575 cubic inch engine. They use a methanol injection system in order to get more torque. These impressive engines can get around 1,250 foot-pounds of torque at over 4,000 rpm and more than 1,500 horse power at 8,500 rpm.

Figure 2 http://hyperphysics.phy-astr.gsu.edu /hbase/thermo/imgheat/heaengcyc.gif