912 Coolant Hose Routing on Kitfox w/ 912

jean-francois naud wrote:

I remember these two hose are really hard to fit with engine mount (Kitfox 4)and i have to remove some elbow to change there direction..because hose hit the engine mount .

maybe That is why your builder decide two change the cylinder ?‍♂️

Yes, that's why, the direct line between #4 and the pump has the engine mount directly in-between.  Looking at rotating the cylinder inlet elbow.

Roger Lee wrote:

I've not ever seen this, but swapping those two hoses shouldn't make a difference. They do equal duty and flow from the pump and through the heads.

That's my initial thought as well, but didn't want to assume.

Sam Purpura wrote:

It’s my opinion that it’s not a good idea to connect the pump outlets to cylinder tops. Hot water will rise naturally and should go to the expansion tank. Reversing that flow just for convenience makes no sense.

Wasn't that bad, only the lowers were swapped between #2 and #4 at the water pump.

In re-doing my coolant hoses I have arrived at the same situation. On the right side of the engine because of the way the pipes are pointed, it would be easier to put them back opposite of the way they came off. It would seem that if this is a continuous flow of coolant rather than some reciprocating process, it would have no effect. If the Kitfox has X# of hours this way, that theory would be validated. I don't want to change the angle of the tubes on the water pump and having read this thread I am going to route the hoses the least difficult way. 

I am familiar with systems that require equal lengths of hose or tubing such as fuel injectors but the Rotax 912 looks to be just a circulating stream through a centrifugal pump. I agree with the poster who stated you could not just run the hoses anywhere on the engine but that is not the issue here. it is simply swapping from one lower port to another on the same side. Rotax might not agree and I'd respect that but I don't see any warnings from them to be sure not to do this. Having said all that, I am obsessive about doing things the right way but I don't see this as compromising anything. And I think moving the tubes would introduce more chance of a problem. Rans S6S dynafocal mount.

If the diagram shown (with red rings around the swapped plumbing) is correct, the effect would be to reverse the coolant flow.

If there is no reduction in the flow rate, it is unlike to cause a problem.

However my concern would be the pump end - what might be the effect of having coolant enter/exit from a non designed/intended direction, on one side of the pump and standard flow direction, on the other?

Centrifugal pumps have veins that force liquid in a specific direction - The outlets are likely optimised for a specific flow direction, changing one side, may have a negative impact on the whole pumps efficiency. 

On rechecking the diagram, I now see that the direction of flow has not been changed , just the points at which the flow comes from - conclusion - no negative impact.