CHANGING BOOST ON A MPI SUPERCHARGER

[yamaha_junky626]

I AM CHANGING BOOST ON MY MPI STAGE ONE SUPERCHARGER, RIGHT NOW I HAVE A 24 ON THE MOTOR AND A 26 ON THE CHARGER, MPI SAID 26 ON MOTOR AND 22 ON BLOWER WOULD BE 10LBS OF BOOST, BUT I ALSO SEED THAT 24 ON MOTOR AND 24 ON BLOWER WOULD BE 10LBS. WHICH ONE DO I GO WITH TO GET 10LBS. WILL BE RUNNING 50/50RACE GAS. THIS IS ON A SUPERCHARGED ATTAK

 

[ProstockBenji]

24 /24 is 10lbs of boost.

 

[BlgsRX-1mtn]

The boost depends on where you clutch the sled to run. If you run the MPI RPM target numbers. the 24/24 set up will get you about 8 psi on the Atack/APEX/RX-1 4 cylinder motors. Run the motor up closer to the rev limiter and you will get 10 PSI though (remembering this from posts by hammer and his APEX set up).

I run the 26/22 pulley combo on my RX-1mtn at the 9600 RPMs but I don't run a boost gauge. My sled has ran flawlessly with this setup for ~ 1300 miles now on 50/50 110 race and 91 premium fuels.

Jim

 

[doo_man]

Boost chart!

 

[SoCoRX1]

i run a 22 top and easily see 10lbs on my boost gauge

 

[yamaha_junky626]

pulley

from what it sounds like 24 24 is 10psi at sea level and 26 22 is 12 psi at sea level and around 10 psi at mountain elevation. i,m just going to run the 26 22 since either is supposed to be safe on a 50/50 race fuel premix

 

[SoCoRX1]

i run 91 octane at 10,000ft