Norris, who won the season-opening race in Australia, said: “There are just certain things that don’t allow me to feel what I need to feel and those things are what allow me to drive to the level I can drive at, to get pole positions and drive at the highest level in racing.
“We’re talking about small things. When we’re talking about qualifying at hundredths and thousandths of seconds, that’s what I’m complaining about. He is maybe more naturally able to adapt and I also think it is a driver’s job to adapt.
“It’s clear there has been some changes and whether it’s suited Oscar or he has done a better job of adapting, that is not for me to waste my time on.
“But it has hurt me and I have not been able to be at my best level, the level I was on at the end of last season.”
Norris said there was a series of upgrades coming to the McLaren car over forthcoming races that should help him.
But he added: “I don’t just want to rely on that, there are things I am working myself and hopefully that will be a better fix.
“It takes time, some of these things, so I just will keep my head down and working on my things.”
Piastri is due to speak to the media later on Thursday at the Hard Rock Stadium track in Miami Gardens.
