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Pat Panzera wrote:
Here's some info on the HP required to run the Corvair fans.
http://corvaircenter.com/phorum/read.php?1,395865,page=1
One of the early Corvair designs, made from steel. It's heavy at
8 lbs, but I'll be cutting away a large portion of it, and if it
works as well as I hope I'll keep searching for something lighter.
Cost me $7. The shipping was $13.50 8*)
Oh, if I could only be so lucky to have it eat 27Hp. 8*).
All my numbers are from memory here, 'cause I'm at work and I'm not going to look them all up again. But they should be close enough to get the idea across.
At 6000RPM, the 13B will let 275cfm of 14.7 psi air pass at 100% VE. At 6000rpm, this fan will require somewhere around 20Hp and move 2700cfm of air. For all intents, the engine is going to look like a big blockage. The fan will pump up the static pressure as high as its tip speed will allow, and then will just keep moving the same air around in a circle. The latter activity will require very little energy. Other calculations that I've done show that moving the 275cfm at the 80m/s tip speed that I'll get out of 10.5" will take about 4Hp. I could be wrong.
How will I test all this?
Step 1: Put the blower all together with the exit blocked and mount it in my drill press. It only has a 1Hp motor, but I won't actually be moving much air. That will tell me what the maximum static pressure I can get at about 4300RPM, the maximum I can get out of the drill press.
Step pre-2: Tune the engine to get it running somewhat reasonably well for the follow on test.
Step 2: With the blower on the engine, record the manifold pressure at speed with intake removed from the blower. I have an elbow in the intake system that I can simply turn around, so this is easy.
Step 3: Shut the engine down. Turn the elbow around to bring the blower into play, then crank 'er back up.
The data logs will show whether I've wasted my time or not.
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