You here people talking all the time about a 2.5, 2.6, 2.8 and 3.0 chargers. They are refering to inches on the inducer of the comp wheel, correct? So if i want to measure a turbo to see what it is, i could measure the outside of the wheel i can get to with the cover on, and it i will tell me if its a 2.5 or 3.0... correct? Or does the cover have to be off for the measurement? I"m looking at a couple of chargers, and the guy doesnt know what he has, and i want to know the size of them. Its not for my truck, its for a different project, so i just needed to know how to tell what size the inducer on the compressor is. Thanks.

Just measure with calipers, or you can use a dial bore gauge.

cover does not have to be off. Just measure the inside of the hole where the compressor wheel is. The wheels are always a little smaller than the bore, but people always go by inducer bore size anyhow.

sounds good, thanks!