That's true, it has nothing to do with the water pump.....that has to do with removing the thermostat. The impeller question (6 or 8 blades) has to do with water flow volume. Most times using an 8 blade impeller pump won't cause a problem, but, not always. I've seen A/C engines with the 8 blade impeller pump have cavitation/foaming problems. I haven't had or heard of a problem going the other way (6 Blade on a non-A/C engine) but, that may just be that there was enough flow and a large enough cooling capacity to mask that problem. From the factory, non-A/C cars used an 8 blade impeller pump, and the A/C cars used a 6 blade one. Opposite of what you would think, right? Well, the reason is that they turned the two pumps at different speeds. Non-A/C cars had a larger diameter water pump pulley than an A/C car, so, it spun slower than an A/C pump. The slower spinning pump needed the extra impeller blades to have the same flow as an A/C pump with only 6 blade, but, was spinning faster. With all sorts of pulley and pump combinations, some (most) will work fine.....some won't. Add various radiator sizes and capacities along with different thermostats, and you have almost endless combinations.....not to mention weather operating temps and conditions.
