forgive me if this question has been asked before. Im still learning about how to pick the proper turbo for what i want. the part im having trouble with is the a/r ratio. now is it the higher the number, the faster itll spool or is it the smaller the number? or am i completely off the wall? i have the maximum boost book, and its a huge help. thanx in advanced.


horsepower is the force that determines at what speed you hit the wall, torque is the force that determines how far you take the wall with you after you hit it.

if you're speaking in terms of the turbine, the smaller the number, the less CFM it needs to spool.

in other words, the smaller the number, the lower the power comes on RPM wise.

arbitrary numbers for the sake of argument...
if all other things are equal:
.48a/r will spool by 2000rpm
.63a/r will spool by 3300rpm
.82a/r will spool by 4500rpm

but again, these are ARBITRARY numbers just to give an example.

good info about a/r:
http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html