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hi all.....
just about done changing out the Powerdyne bd11a on my 360 Chrysler for a V2 SI that i have just purchased. The powerdyne was not going to give me the boost i want.
Anyways what i would like to know is what head unit pulley to use for say 12psi boost @ say 6000rpm,:fat: 7" crank pulley, 3.5 rear, auto. i have a couple of spare pulleys from the powerdyne, but they are 2.7 and 2.9. think they may be too small.
cheersAttachment 1916
welcome to the site.
looks like it packaged under the hood well.
what kind of boost are you getting now before changing pulleys??:confused:
about 6, but that was with 6" crank pulley and 2.7 on the head unit.
Powerdyne bd11a has max impeller speed of 38,000rpm with an internal step-up ratio of 3:1;
therefore 6psi-boost with 6" crank pulley and 2.7 on the head unit = only 21960 blower speed @ 6000rpm-engine speed =122% overdriven
with 7" crank pulley and 2.9 on the head unit = only 25380 blower speed @ 6000rpm-engine speed =141% overdriven
with 7" crank pulley and 2.7 on the head unit = only 28620 blower speed @ 6000rpm-engine speed =159% overdriven
wallace has many calculators on this site.
http://www.wallaceracing.com/blower-od-calc.php
this one can tell you the %-of UD/OD ratios of the crank/blower pulley, then times by the rpm and times by the 3:1 step-up ratio to end up with the blower speed at engine rpm :semi-twins:
you can spin the blower much higher than you are now with the 7''crank and either 2.7/2.9''blower pulleys
providing the max-blower rpm and set-up ratio i used are correct:torn: