terravast4

iTrader: (25)

Anyone know what size pulley for radix to get around 8 lbs boost?

FastCrewCab4x4

On my 6.0 I get 7.5 psi using a 3" pulley. I think on your 5.3 you will need a 3.2" pulley..

old motorhead

iTrader: (10)

3.1 on mine yields 9psi with a bigger cam, LT's, and true three inch duals (no cats). 'Bout halfway between stock and mine ought to get you close.

trever1t

iTrader: (14)

What size pulley do you have now that makes 5.5lbs? Boost is a measure of resisitance at the manifold, some mods will increase or lower boost like intake, heads, cam and exhaust.
A .20" smaller pulley will increase boost ~1.5-2lbs.

I use a 3.2" to make 8.5lbs.

terravast4

iTrader: (25)

I have a 3.4 right now

trever1t

iTrader: (14)

It is highly recommended to pully down only .20" at a time so go for a 3.2" pulley, tune and see how that works. I found it to be a major difference going from 3.4-3.2"...Boost comes on sooner too!

terravast4

iTrader: (25)

Thanks for the info guy's.

terravast4

iTrader: (25)

If I go to a 3.2 pulley now and add heads and a cam later could this then add more boost because less restriction?

trever1t

iTrader: (14)

A less restrictive intake might increase boost levels but better flowing heads/exhaust will actually drop your boost level while power levels increase. Heads or head work would be a last mod, the right cam can make a significant increase in performance in an FI application.

Blackice1

My 5.3 with longtubes and k&n makes between 8 and 9 psi with the 3''.