I think Al and Bill have been trying to say this politely but .... We all agree that the EWP flows less than the standard pump by alot (maybe only half to 1/3th as much?). That's OK. But if you have less flow then the radiator MUST be larger for the engine to obtain equal cooling. This equates to more drag. Now does the EWP save more energy than the ~3HP the mechanical pump uses even when the extra cooling drag in factored? In other words, does the EWP save 3HP worth of cooling drag? I suspect that the mechanical pump is more effecient but can't prove it. Bill, Al, Ed and some of the engineers can probably give us a good idea though (and have). No numbers here, I'm just trying to piont out the real issue - energy expended at WOT, cruise, and climb.
And yes, climb is particularly tough to factor. I personally want to be able to perform a max performance climb at 90 F. at sea level and will lower the climb rate as temps and altitude increase. I live in Arkansas where we often see over 100 F. in July and Aug. so this isn't just casually thowing out a test case.
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I agree, but OTOH less flow makes everything else more critical and a higher temp drop across the radiator is needed.
It's true that changing the flow rate will change the equilibrium temp of the coolant. That's the reason the Davies Craig controller works. The only real question is how much flow is enough. There are so many variables, that I defy anyone to calculate this for anyone's aircraft with any real accuracy.
Todd is probably doing a little better than 9 GPM as that was measured at 12 V. He also got 7.7 GPM with a couple of GM evap cores which is still better than I'm doing with one pump.
I'm hoping that his instruments were more accurate than yours. IIRC, your gauge started at 5 psi, so I would not expect it to be at it's best accuracy at that level. At least I'm hoping it's not reading too high :-)
I ended up ordering a paddlewheel flowmeter that has a 3-30 gpm range. ( http://www.mcmaster.com search for item number 3562K13) As far as I can tell, it does not have a remote readout option, but that's fine. It's about $120 cheaper than the last one, and should be much better as well. I still haven't decided if I'll mess with it this weekend. I'd like to, but I have so much other stuff that's more important to do. I might just play with both pumps in the garage next week sometime.
I might also conclude that the pump is over designed for 100 HP per rotor. :)
Agreed. The larger Meziere pump you're looking at is billed as being suitable for high HP applications. Let's face it, 200 ain't "high HP". I don't think there's any doubt that the stock pump is overkill.
I think the only way the EWP will ever be truly accepted by this group (the other group is hopeless) is when there are numerous flying examples. Right now, Todd is the only one who gets full credit, but that's not good enough because he lives in the "great white north". I have no real motivation to change my system, other than wanting to prove that this works. Not sure if that will be enough motivation though.
Cheers,
Rusty (I believe)