| Thanks for that. Great information!
So it seems that the radiator flow restriction itself is not adequate, in some circumstances, to avoid cavitation.
I remember with my Midwest they dictated a coolant reservoir just prior and superior to the pump. Was that their way to prevent cavitation?
Now comes, at least to me, the age old question as to the advisably of using an electric coolant pump. If used, and/or successful, do these need a restrictor or is one built into the unit or they, as was expressed by the late Paul, totally worthless?
Rich Sent from my iPhone
Cavitation is caused by a spot of low pressure. So a tiny imperfection in the face of the impeller would be the start of each event. It could be a sand blow hole. It could be an imperfect bit of machining......Note that impellers are sand cast crap. Not machined on every surface at all. So many variations in shape and surface finish......or" as cast" as you may have seen on many drawings. This is because almost any shape at all would work well as an impeller in a pressurized system. It looks like hell because it doesn't matter what it looks like. Works just fine in a car...........Pumps for more critical installations have impellers that are 100% machined and polished. Even a stamped steel impeller is a big step up in performance and reliability due to a more uniform shape. More modern pumps have smaller yet better performing impellers due to the interest in fuel mileage. More fluid flow for lower power input.
I ran my engines with a 5/8" hole on the outlet to the radiator. At first I made a restricter mounted where the
the normal thermostat would have been. Years later I built it into the Norice or, the aluminum water outlet
to the radiator. I never had a cooling problem in 30 years of racing. But I also know that more than 1/3 of the total cooling load is in the oil. I cooled the oil and the water stayed below 180 degrees. I used three 44 row Setrab oil coolers. Your results may vary...............LEH
In a message dated 6/10/2020 12:01:53 PM Eastern Standard Time, flyrotary@lancaironline.net writes:
OK, but then why just one blade? Finn On 6/10/2020 11:34 AM, lehanover lehanover@aol.com wrote:
All of the rotary stuff left here with the last race car, so there is nothing to look at. So...this will be a guess.
12-A before 74.
A look at the front iron could tell the tale. Mazda kept removing bolts from anything they could, so, more bolt holes generally means older piece.
Cavitation damage can be caused by letting the pump output outrun the suction side supply. So just limiting the output a bit with a restricter eliminates this kind of damage. If you have seen a water jet cut through a 1/2" steel plate you might think this could happen on one long test flight...................
LEH
In a message dated 6/9/2020 1:30:41 PM Eastern Standard Time, flyrotary@lancaironline.net writes:
Ryan, is it possible your water pump is off an old 12A?
Lynn Hanover is on this list and would be able to answer anything about 12A's ... maybe reach out to him directly in the subject line??
Jeff
-----Original Message-----
From: Jeff Whaley
Sent: June-09-20 8:02 AM
To: Rotary motors in aircraft
Subject: RE: [FlyRotary] Water Pump
Hello Ryan, this is a photo of my water pump from a 1988 13B ... Jeff
All,
Can anyone point me towards the correct water pump? The one in the top of the photo is the correct one. The one on the bottom is obviously incorrect. It's the second one we've ordered.
The first one that I ordered looked identical to my original one. However, when it arrived it was similar, but about 1/3 smaller than mine. When I ordered this second one we all (Carquest employees) poured over the pictures to make sure it was correct. When it arrived it had one less bolt hole than the one in their pictures.
I have a Powersport 13B. Any ideas what pump they ran and where a guy can order one
Thanks,
Ryan
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