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supercharger efficiency

Old 09-02-2011, 05:37 PM
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Originally Posted by tnc110
Ouch! So plan on 10k huh? Sounds like buying a Nitrous system...sounds cheap until you add all the things you want/need above the initial kit...

i'm used to be a nitrous heads up racer, and i wouldn't put nitrous on my boat for anything.
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Old 09-13-2011, 10:12 AM
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Physics says that a motor can't be more economical at a given rpm if it is dragging along the parasitic load of a blower. You can't defy physics.

BUT since the blower allows a higher pitch, your cruise rpm drops, thus changing the parameters and giving the result the above guys are talking about.

Here's how it works.....

Right now, you run let's say a 24 pitch prop. Let's say your most economical cruise rpm "for the motor" will be around 2400 rpm due to the torque curve of your motor. Your hull, though, at that rpm isn't fully on top of the water and running freely at that rpm. Your hull's best cruise speed let's say is 36 mph, yet it takes 3000 rpm to get there. So you end up cruising at 3000 rpm all the time, giving up the sweet spot in the torque curve at light throttle openings.

With the blower, let's say you now run a 28" prop. Now you run 36 mph at your 2400 rpm. Even with the parasitic losses incurred by driving the blower, you get to run at your motor's most economical rpm, and your hulls sweet spot at the same time.

Bottom line is that if you ran that same 28" prop without the blower, and ran it at the same 2400 rpm, you would get slightly better economy than the same setup with the blower, but the boat would be a pig, would be hard to get on plane, and would not accelerate for squat.
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