Arif Khokar
Under loads it probably would. But again, plenty of a material from the people that make engines "designed to use 91 octane" have said that running 87 won't hurt them. This is because most of the engines only need the higher octane to achieve advertised performance, but very little everyday driving conditions would call for such max performance.
How many times a day do you think Scott actually needs to call up all 400 horses under the hood of his 'Vette? I am not saying that he could get away with running 87 in his 'Vette without knocking even at typical street speed as his car is designed with , but most people driving cars normally aspirated engines that call for premium can indeed use regular without trouble.
Supercharged cars are another issue. I have had a couple (one was a diesel so it doesn't count). My TBird SC would cruise at 70-80 without detonation on 87 octane, but put your foot into for any reason, it sounded like a sewing machine. The SC had a slightly lower compression ratio than the normally aspirated TBird, but actual compression was of course higher. Like many supercharged engines, it often used some boost under everyday driving conditions.
