SC Pulley Help

[BSouders80]

Sometimes I surprise myself. I don't have a 2.75" SC pulley. It's 2.875" So I ordered a 2.75" and a 2.60" Griptech pulley for the whipple. When I read Biggest's post, I saw the 14-16 psi for street and 18-19 psi for race. My plan - When I get the pulley that Livernois shorted me, I'll those 2 before I go back to OEM size on the ATI OD pulley. Biggest said that his pulley was a 1 off when he got his OD pulley from ATI. I'd hope that they would recognize the defect and make that change in their manufacturing process. Definitely something to look into more though. Thanks Mike. I do have a boost question. With the tune, should a tuner be able to modify when the boost comes on? Like now, it's 2/3 throttle is before the boost comes on. I've talked to Lund racing as well as Houston House of Power about some custom dyno tunes. Not sure if Livernois will flex on changing anything that deals with power on their tune.

 

[MTF]

2/3 throttle???
I was getting boost at around a 1/3 throttle but I was running full stock exhaust so there is some back pressure.
I never trusted the boost readings, the SC is working, and it takes time to build up enough pressure to make the gauge move.
You're spinning the SC probably more than you should with what you have or close to it.
I was told by Dustin Whipple that there becomes a point were efficiency of the blower gets nullified.
Next step was to go bigger.

You can play with the bypass valve spring, but it's risky and drivability will probably be compromised.

 

[BSouders80]

Not a whole lot of back pressure on my setup. 1-7/8" ARH Long tubes, 3" SW exhaust with GESI cats. I don't disagree that at some point, you lose efficiency. I run a IHI SC on another setup and I'm running 2.75" there with 10% OD pulley. I'll put the 2.75 on and see what happens with my boost. Just for curiosity. Not sure if my tune can handle it but I'll find out.