914 fuel pump system

The order of the photos did not come out like I wanted.  You have to click on the fuel block pdf.  The fittings for the manifolds are $10 ea and there are 10 of them.  May want to think about making the manifolds like in the photo.  If I did that I would use square aluminum blocks.  The left hand homemade manifold in the photo must not have been drilled straight through but drilled partly through from each end.

"  I will have to cut one of the manifolds in two and seal up cut ends. "

No need to cut it in half.
At the midpoint of the manifold, drill a cross hole slightly larger than the through bore.
You can then either thread a set screw in the hole or press and Loctite a short piece of rod in the hole for the same effect.
Weld the rod in if you have the means.

Just an historical note for you 914 users.  In its original configuration Rotax used to call out parallel pumps.  This however had some issues as fuel pressure at WOT and max RPM may lack enough to overcome the turbo boost air in the float chamber.  At critical pressures the boost pressure would in effect vacate the fuel from the float bowl on takeoff.  The solution is to run your pumps in series, as is called out in all the manuals today.  Pumps in series can maintain the pressure much better.  A single pump can run the engine just fine under normal flight however the extra boost for takeoff is the real problem.  most of the time we can get away with it but for sure series is much safer than parallel on this system.  You can see the boost map in the manuals and at 108% power there is an extreme jump in power where the turbo maxes out to give you takeoff.  At that point the same pressure is found in the airbox and the fuel pumps must maintain the delta between boost and fuel pressure. 

Thanks for the "hint".  The manifolds are in Canada and they can not ship to the States.  

I will build my own out of 1" solid square Aluminum.

Allan

Allan,

How did your fuel pump manifold system work out? It looks very clean! Would you change anything? Getting ready to build similar.

Thanks!

Dan