Austin Seven Water Pump Addition - Test Results

Test Car And Motor

The car and motor used was a 1934 Australian bodied Austin Seven ‘Comet’ currently using a 1935 Ruby 2 bearing motor. The radiator fitted uses a modern (3-roll configuration) core. The block is relatively clean and the car has never boiled on hot Adelaide summer days. The motor is bored to .080" over size, has polished ports, a custom manifold, and uses a single 1 1/8" SU carburettor. The motor is also fitted with a deep finned Cambridge alloy head and 7 pint finned alloy sump. The car uses a four-blade fan, common to many export models. My main concern with the thermal siphon system was opposite to most peoples concerns. The car would never overheat under idle or heavy traffic conditions on extremely hot 40-degree days. But under fairly fast driving conditions of 80-90 kph (well fast by my standards in an Austin Seven!) the temperature as measured at the top radiator tank would start rising to 210 degrees after 10 or 15 minutes. This really did not presented itself as a problem but I was not that happy with this temperature so close to boiling. Thus the idea of this new electric water pump had some appeal. I have taken advantage of our very hot weather to run some tests. Keep in mind that an electric water pump delivers the same flow rate at all times and is not dependent on engine speed. The quoted flow rate at 6 volts is about 40 lpm (I have not measured this but this figure is quoted by the manufacture).

Results

Without pump fitted:

Air temperature at 37 degrees C

Idle temperature after 20 minutes – 180 degrees F

Running temperature after 10 minutes at a speed of 85 kph – 210 degrees F

With pump fitted (switched on continuously):

Air temperature at 37 degrees C

Idle temperature after 20 minutes – 175 degrees F

Running temperature after 10 minutes at a speed of 85 kph – 170 degrees F

With pump fitted (switched off):

Air temperature at 37 degrees C

Idle temperature after 20 minutes – 185 degrees F

Running temperature after 10 minutes at a speed of 85 kph – 210 degrees F

Conclusion

Very useful under our hot summer conditions, the fitting of the pump seems to have very little impact on the original thermal siphon system. I think the simplest use would be to switch it on as required – assuming you have a temperature indicator of some description.