belt size?

[mrpork]

okay guys need a little help. I'm putting on a Whipple with a 3.00 pulley on it. with the 4lb lower and the 3-100mm 1-90 mm pulleys what size belt should i use

[Ram77mus]

That 4lb and a 3in upper will be to much boost for pump gas safely. I have seen 21-23 psi with that set up. If you want to run that 4lb then up should run a 3.5 upper witch will be around 17psi.