A Kawasaki ZX-10R superbike engine of 998cc displacement takes in roughly 7,000 liters of air per minute. But if a compressor forces twice that volume of air into it, its horsepower will double. A limit is set to this process by heat. As the combustion flame spreads from the spark plug, expansion of hot combustion gas compresses the unburned charge remaining. As unburned charge is heated by this compression, pre-flame chemical reactions within it accelerate. If these reactions go far enough, bits of unburned charge go off before the flame front reaches them, generating shock waves of sonic-speed combustion that make the noise we call "combustion knock," or detonation. The destructive effects of detonation set limits to our power hunger. Typically, compression ratios of supercharged engines are lower than those of unsupercharged engines to subject the fresh charge to less heating, thereby staving off detonation. Supercharged aircraft engines of WW II typically had compression ratios around 7:1, while engines of F1's first turbo era ran at about 9.5:1. Splitting the difference, we get about 8.25:1.