I took some pictures and closer measurements of the two impeller designs that I have (AC equipped and non-AC equipped 1500).
The first four images are for the "AC" style, with indications of where I measured. These measurements may not be absolute, and may not even be relevant, but they should offer some idea of how the two impellers compare. The second four images are the same views of the "non-AC" style (same measurements were taken on both).
I'm hoping someone can confirm if one of them would generate more fluid pumping action than the other.
AC pump and housing:
Non-AC pump and housing:
The dimensions for each are as follows (using the lettered indicators in the pictures):
AC pump and housing:
A) 60mm
B) 27mm
C) 35mm
D) 16mm
E) 15mm
F) 63mm
G) 37mm
H) 80mm
Non-AC pump and housing:
A) 64mm
B) 33mm
C) 32mm
D) 10mm
E) 10mm
F) 64mm
G) 40mm
H) 85mm
Both impellers have 7 blades of about the same contour and shape, but different size.
As you can see in the pictures and from the dimensions, the AC pump has a slightly smaller diameter impeller and housing but significantly taller (deeper) and longer impeller blades...compared to the non-AC pump.
Perhaps a good visual comparison can be made by looking at the oblique angles of the two (the third picture of each respectively).
I do not know to what extent the different dimensions make to the pumping properties. Is the overall diameter/size more critical than the blade surface area/size? The AC pump has larger blades but the non-AC pump is larger overall. As I understand another factor that may influence a pump's performance is the difference between the outside diameter of the impeller compared to the diameter of the housing around it. However both of these pumps have basically the same clearance (10mm) on either side of the impeller. Is it fair to make any assumptions solely from these differences, considering everything before and after the pumps are identical?
Another difference between the two versions of pumps is the sizes of the drive pulleys. As noted earlier there is some variance between examples of each type so the drive ratios are not completely consistent. But the AC pump has roughly a 120mm driver (crankshaft) pulley and a 109mm driven (water pump) pulley. The non-AC version has roughly a 130mm (crank) and 114mm (pump) pulleys. Using a simple online calculator, that indicates ratios of 1:1.1 (AC) and 1:1.14 (non-AC), and at a engine RPM of 2000 the AC pump will be rotating at 2202 RPM, while the non-AC pump will be rotating at 2281 RPM. So the non-AC pump actually spins faster than the AC pump. Although as noted, these will differ from one engine to the next due to several options of pulley sizes for all of them. If I were to guess, I imagine they were intended to turn at the same speed (pretty close to a 1:1 ratio).
Appreciate any input on this.