Alky will typically yield a 10% (roughly) gain in power if properly tuned ( AF ratio, timing)regardless of compression. Lower compression engines benefit as well as higher ones. Beauty of alky is, once you go to it you can raise the compression way up and get even more gains. This 10% gain is about 1 hp ona stockish clone (like Barry said) or about 50hp on that 500hp big block dragster you have in the garage. Biggest error most make about alky, is buying way more than they can burn in a short time (few weeks) and have it setting around. You MUST keep it very well sealed up. If not it will become diluted with water very easily. A regular type fuel can with a slip on cap on the spout is not good enough. Not even close. Good luck.