It's certainly not a bad idea. I do still have my 255 as well. Any idea how that would work as a second pump when coupled with a 450? At that point I would be injector limited at 925 or so plus the meth so I would think its good to over 1000.

 

Ever think just motor moves enough air that your pulley ratio cant keep up?

Dude i got my procharger off could only make 7 psi on my same pulley i make 12 psi and drop down to 10

Same pulley ratio is supposed to be 16 psi


I didnt have belt slip i just over spun the blower


Buddy on a 6.2 with ported heads could only see 11 psi on his jack shaft whipple 2.3

Same blower and pulley only sees 8 psi on his 416

 

Yea that has crossed my mind, but generally with a PD blower that doesn't show through with boost dropping off. It just shows as a consistently lower boost number. I peak, hold, and something starts to choke it. I will get a gauge on one of my vacuum ports at some point and measure the restriction, but I anticipate I will start to see vacuum just as an NA set up does when revving high even if only by a couple kPa.

To your point the 1900 I have was used on a stock 5.3 and made 10PSI, but on my cammed LQ9 with the same exact pulley it only made 5.5-6. Its why I chose the parts I did on this 370. A big cam and relatively big heads to try and lower boost to some extent.

Your boost dropping off is from over spinning the procharger. A procharger max RPM is there simply because the impellar spins so fast beyond its recommended max that it creates a massive amount of turbulence. This slows down the air and it literally cant flow as much. I am nowhere near that point with the maggie.

 

Another thing ive saw with a blower like yours is the mid plate to intercooler and how the blower attaches

This was on the lightnings when swapping to none specific blowers....air was hit a shelf and not gain anything, boost stayed same but lost power up top where as a specific blower carried better

The non specific made more torque but graph showed it was a flow restriction

 

Thats not entirely true.

 

True. Its not EXACTLY at the advertised max RPM. I know you have had luck over spinning them slightly. You can over spin them, but when you eventually hit that wall of losing boost rather than just flat lining, that is very likely the cause.

 

Procharger is a centrifugal compressor, just like a turbo. PCs typically have a smaller trim to bring the power in as soon as possible and this generally extends the compressor map vertically to higher pressure ratios. At some rpm though, the compressor will choke and no matter how much harder you spin the compressor it will not flow any more air mass.

 

Good friend of mine made a custom plate for the Lightning guys if ya ever need one George.

 

I know of JPS plates

 

Rob does your IAT go up when this "restriction" happens? Or is it belt slip? Is my guess... Ya switching to a return system is a good idea run the 255 as primary, and 450 on a hobs. Just keep it under 70 psi the pumps seem fail more often at that pressure. Maybe your just noticing and feeling the fuel system issues at higher rpm on longer pulls.