i noticed my car didn't seem to have a mass air flow sensor, (91' z28 ) and i was reading on a site that they changed from the mass air flow system in 1990 to the speed density system, this suposedly gave it more HP. what is this system, and how does it work?

 

Well, to put it simply... I uses a pressure sensor (MAP) that measures the vacuum in the plenum and the tempeture of the incomming air to calculate air flow. In general MAF systems are better becuase they have alot more room for changes. But in 3rd gens the SD computer was a better design and the MAF can become a restriction. (No aftermarket MAF housings like the LT1 guys)