If it's a manifold mount, with max pulley sizes, it will make 26psi mathmaticly before pumping losses. So about 24-25 real word. That with a IW 10% over crank and 3.25 blower pulley (smallest that will fit).

Now, even with a stock crank and 4" blower pulley it will still mathematically make 18 PSI. You would need a 5" blower pulley to get about 7-8 PSI on a 4.8.

 

I just think a 4.8 built with a good bottom end and a roots style blower would be sick, you don't see many of those besides maggie'd versions.

 

The math looks good but,those numbers get scewed once intake elbow,TB,Intake track,filter,blower heat soak and,last not least belt slippage.One way to control boost on PD's is to restrict the intake long as its not real bad.It works i have done it a few times screwin around.You know when its too much the iats skyrocket.

 

Well, Mine has the max pulley setup that mathematically should make 20psi on my 5.7 and I see 17psi in third with some belt slip, 6900 DA and sky high iat's!

 

I would rather be a little big on the blower then too small like most of these guys do. Then complain about IAT temps

 

Damn that "blows" as in sux *****....You wanna/gonna work some P.D. VOODOO on the kit?Its not the blowers fault power is down they are capable of the advertised numbers.The thing i found out messin with mine is twinscrews work great only if you have a proper air supply.They are not forgiving to high iat's or restrictions pre compressor like a turbo,centri,or even roots once they ecounter either or the listed issues power falls dramatically.Thats why people love'em or hate'em.The high iat's you see get compounded because the unit has a internal compression ratio.So the down side is the pressure on the outlet side of the blower gets trapped in the rotors while they rotate back up in the case.Taking a **** pot of heat with it which in turn mixes with the lastest air charge entering the blower thous compounding boost internally.When this occurs the blower gets much harder to turn and air density/flow suffers.It seems KB's are even less forgiving when encountering restriction/iat issues.I believe the 4/6 rotor design to the lysolm's orignal twinscrew 5/3 design is the culpret but,thats jus a theory.

 

My IAT's jump up about 125* or so in a 1/4 pass with this setup and meth (2 nozzle's M14 post blower, M5 pre-blower). They also fall as fast as they go up like the intercooler just can't absorb the heat fast enough. Pre-blower intake track couldn't have any less restriction, as the elbow into the blower has been ported to it's max size and flow and I have a 90mm TB with 4.5" to 4" air tube to a big 4"x10" cone filter that's getting fresh cold air (no MAF). I'm spinning the blower right about 15,000rpm at 6200 shifts. I'm gonna try moving my big meth nozzle (M14) from after the blower (it sprays right into the blower discharge) to before the TB and see if it makes any difference. It's not hard for me to get 200*+ with this setup.

 

Ahhh finally someone else with a KB here. I've always wondered how the on manifold setups compare with the off manifold setups. Sounds like you have some challenges with IATs. On my off manifold setup my IATs go the other way during a run. At a stop light it heat soaks to about 125 on a hot day. When I get moving it is about 15-20 degrees above ambient even at the end of a hard run. Its all in the intercooling. I would be interested in seeing some of your logs.

I think a 2.8 is waaaaay huge for a 4.8 - blower cam is a must if you choose to go that route.

Good Luck

 

Only one way to know how well the compressor is breathing.Check vacum at the inlet to the rotors.
As for the heat exchanger well you need to tap above it and mearesure where the rotors discharge.Should only be about 2#'s higher then manifold pressure.If that checks out then the air is flowing pretty good or at least not the restriction your looking for.
The meth will scew the test some.I couldnt tell you how much though.

 

I do have a vac gauge in between the TB and compressor and it shows less then an inch vac at WOT.

Here's a EFILive log of my highest IAT Last weekend at the track, this was with no cooling (adding ice) of the intercooler water. It set's around 128* most of the time under normal driving.