i have the 4.8 with the whipple supercharger and was wanting to reach 10 ibs of boost.My pulley size is 4 5/8 and with this pulley i am making 5 1/2 pounds of boost.i need to know what size pulley to get 4 1/8 ,4 , or 3 7/8 please help.

 

every 1/8" is about one pound. a 4 1/8" pulley would be 9-10 pounds of boost. just a warning though, i have a 9 lb. pulley that i use at the track but i have to run 100 octane race gas or it will spark knock pretty bad. i'm pretty sure 6-7 lbs. is the limit for pump gas

 

Well I dunno if there is a difference btw a twin screw and a roots as far as boost limits but I know my buddy has a Lightning and that thing makes 9-10 lbs easy on 93 octane... might be more but not sure...

Also on another note... what kinda track times you puttin down 454?? I gotta RCSB 5.3 3.73's and I wanna throw on a Whipple...

 

Yellow- I am running a 4.8 w/ a magna charger and am gettin 10lbs with a 3.25'' pulley. You just want to watch that you dont start lifting heads with running to much boost. It suxs. trust me

 

Yup

 

the lightnings and the radix kits can put out more boost on pump gas cause there intercooled. and 01Sierra, it went 13.3@102 a few weeks ago.

 

The lightning does this with an intercooler and a lower compression ratio. the high compression ratio on the 4.8, 5.3, and lq9 limit the amount of boost you can run on pump gas without detonation.

 

You have to be alittle carefull when you get advise about different boost pressures for a given pulley diameter because the following can affect pulley size on your whipple:
- (1) belt set-up or (2) belt set-up
- engine displacement
- crank pulley size for (2) belt set-up

But a good rull of thumb is for every .125" smaller pulley = ~1 psi boost.

 

The way I was going to run more boost(10 pounds) was with the aquamist water injection. It allows you to run 3 to 4 more pounds of boost by cooling the air in the engine. I hope it works out.

 

I plan on doing the same but with smc akli injection kit & methonal & from my guesstimat for 3+psi boost & the injection kit should =~50hp more to the wheels.