Assuming it rotates CCW (as viewed) I would vote for the one on the right. But you should know I only got a C in my fluid dynamics class.
If the impellers are different materials the one that’s softer than the engine block , ie plastic / composite as opposed to metal . So if it comes in contact with said block it sacrifices itself first rather than permanently damaged the block .
Although I suspect the problems that plastic impellers had for some years have probably been resolved, I'd buy the one with the metal impeller because I'm more comfortable with that. BMW, for example, went to plastic, had failures, went back to metal, then went to some sort of composite which seems to be OK. But still seems to be a solution for which there was no problem...well other than plastic impellers are less expensive for the manufacturers. FWIW, plastic impellers (pumps) are seen as regular replacement items by some shops - replacing them at every belt change. Admittedly, belt changes on normal cars have far longer intervals than 3x8's!
If you are foolish enough not to use the one on the left I'll buy the core if it came from your car. BTW Same design used in F40 and managed to keep a 500 HP blown car cool in pretty much any situation.
Aren't the parts available to rebuild the original? I suspect that by doing so you'd end up with a better water pump...
It is an original. Ted Rutland himself got them from the same supplier that made them for Ferrari and I've seen and held them new and NOS. The impeller is slightly wider and taller thus they do not fit on 308s/328s. That said, a 308/328 pump can fit on an F40, it's just not correct. Maybe some left the factory with a 308 impeller, who knows, but the only Ferrari part number for the F40 impeller is 125694 and it is indeed a scroll impeller. The 308 PN is different, 103806. Does not cross to F40. There is a reason Ferrari changed all impeller vanes since the 90s to a scroll type impeller vs the archaic straight vane impeller. The very late 348s swapped to scroll type impellers too. The fluid dynamic science is back on this and has been for years, no one uses straight vane impellers for anything, not even on a PT Cruiser, as they are prone to cavitate at high rpm.
OK you are correct. In fact you are perfect. Does that make you feel smart now? Who the **** cares? Its not the point of his question.
