turbo literature??

hi ive been spending a good hour reading over turbo specs on the internet, and think its finally sunk in, so can someone let me know if what im sayin is right

the a/r of a turbo is the housing size

the a/r size on a compressor side doesnt make that much performance gains

the a/r size on the turbine side makes a big difference, smaller a/rs are better for low down boost ideal for faster spool up and less lag better for applications when changing speeds constantly like backroad driving

bigger turbine a./rs better for higher boost applications when turbo is being used mainly at higher rpms eg track racing


the trim size of a turbo is the relations between the inducer wheel size and exducer wheel size, and the bigger the trim size the more air can be flowed so more power

so the ideal turbo for fast road and track would be a turbo with a larger comp housing and big trim size and a smaller turbine housing but with a big trim size, which would mean bigger inducers and exducers

so a good turbo would be a t25 with 60 trim on the comp and 60 trim on the turbine and a/r 48 comp and a/r 35 on rear and if being used more for track and drag change the turbine a/r to a 49 so more power at higher rpms and let the turbo breath better less back pressure?

is this right ?if so ill be well happy its took me ages to get it into my head, so joiners can learn turbo specs lol

yeah, you got got most of that about right :) a couple of additions to that:

sometimes you can go too big and efficiency drops. bigger isn't always better, it's about getting the right size compressor and turbine for the job.

trim of exhaust wheels doesn't vary as much as compressors. the trim of a compressor doesn't relate to that of a turbine, so just because you have a 60trim compressor doesn't mean you aught to have a 60 trim turbine, the sizings don't relate like that.

in short it boils down to this rule of thumb:

1/ you pick the compressor based on the power you realistically expect to make.
2/ you fit the bigest turbine you can get away with before it gets too laggy for the job.

so do you pick the compressor size using trim or by wheel sizes in milimetres??