5/11/07

I have a spreadsheet elsewhere in this computer that “calculates” various horsepower and torque values from know data using formulae I figured out. I know most of the information is bogus because of, well, bogus formulae most likely. Anyhoo, I plugged in some numbers for Barbara with the supercharger just now. With a 1:1 pulley ratio, that thing will be making 17 PSI of boost and punching out 171 horsepower! Yikes! Again, let me reiterate that I know those numbers are most likely totally wrong, but still… Well, the supermodel needs me. I'll be back to talk more in a bit. Ok, so where was I? Oh right, I was talking out my ass about how much power this supercharger is going to make. I just plugged in a 0.75:1 pulley ratio and got 9 PSI and 129 horsepower. I think a stock A-14 can probably handle that. I'm planning to run an intercooler on it and the carburetor should have a small cooling effect as well. So, I need to make sure the crank pulley is 25% smaller than the water pump pulley I have on the nose of the blower. Is that right? I think so. Yes, if the blower pulley is 5” I need a 3.75” crank pulley. Well, I need to make sure the crank pulley is in the range of 20% to 35% smaller. 0.8:1, 20% smaller, yields 11 PSI and 137 horsepower. 0.7:1, 30% smaller, yields 7 PSI and 120 horsepower. 0.65:1, 35% smaller, yields 6 PSI and 111 horsepower. I'm not taking into account parasitic losses from driving the blower of course but I think below 0.65:1 and that will be a real factor. I also think anything above 11 PSI is looking for trouble. I just had another thought, with the bypass valve continuously venting off most of the boost, this thing is going to make a really weird sound. I just hope a GReddy Type S will flow enough air to do the job. We’ll see. I wonder if that blow off air vented through the face of the intercooler would make it a little more efficient. Follow me on this. Take ambient air and compress it in the supercharger. This heats it up due to (tee hee, doo-doo!) physics. Can’t do anything about that. Now, we take that hot, compressed air and run it through an intercooler. We now have cooler, compressed air. When we vent that back to ambient pressure it should cool even further due to (tee hee, doo-doo!) the same physics that we couldn’t get around before. It should be cooler than the ambient air and thus blowing it through the intercooler should be better than running strictly ambient air through. Of course I does waste all of that air rather than recirculating it back into the inlet of the blower. Oh wait, I think I see the flaw in my design. There really isn’t going to be boost until the BOV closes off and the air is forced into the cylinders. As long as the BOV is open, barring any major restrictions in the bypass system which would need to be rectified lest the whole thing be moo, the air coming out of the blower will swoosh off and not become pressurized. The only cooling effect would be upon first throttle lift after a boost run. Ok, so the BOV will be vented back into the intake of the blower after the air filter. I've got the parts to make that happen. Well, most of them. Of course I need to concentrate on George. But Barbara is licensed and registered. They both need about the same amount of work to be done, if I forwent the blower on Barbara. Actually, Barbara might need less work to make road worthy. Bah and feh! I think I'm just about fed up with this for the week. I'll talk to y'all again on Monday.