So people have been asking how is this project going. To give a brief synopses I found that the original impellers (which were a alloy with chromed centers) were the Achilles heel of the Bosch short fuel pump. The metal decayed in stale gas. Then in modern gas the ethanol ate away at it. As such I started my journey to reproduce. Unlike certain replacements available today, you can't do the impeller out of straight aluminum, it is too soft of a metal and modern gas will start to deteriorate the thin top fins of the impeller within a few years, but the worse issue will be the constant collision of the hardened steel shaft of the armature hitting against the soft metal of the impeller half moon to start the pump running, this is one of the reasons the originals were chromed in the center. It is unfortunately a progressive thing also, as the half moon is started to be rounded the hardened steel shaft will be able to travel that much father gathering more energy causing a collision that will be much more deforming of the half moon and so on in a vicious cycle. So I started with stainless steel which is superior to the original alloy but I thought I still could do better and went with titanium. This is where I turned to people much smarter than I and they explained that titanium will be lighter, hence the impeller will spin faster and will be very resilient to modern gasoline. So we wire burned some examples but found they puckered under the heat of cutting then had to be lapped perfectly flat, an expensive and time consuming job. I took two of our test impellers and have been soaking one of them in the oldest nastiest gas I could find and used another simulating 400 starts and 10,000 miles. These test showed that the titanium was the way to go, no determinable degradation.
Now the problem was how hard they were to produce. Again seeking out people WAY smarter than myself found someone who makes extremely tight tolerance parts for the aerospace industry and he explained that in titanium there is a grain (yes to far generalize" just like in wood") and the reason it was puckering while wire burning was the grain. He supplies us with these cylinders so that the "grain" will be complementary and will lower our cost and effort to making sure each is to the tightest of tolerance. We are working on cutting them now and I should be ready to ship soon. A job worth doing is worth doing right. These pumps have survived 30+ years of running and I would be remiss if I were to put something in them with a really short time expected life. Again when I am done I will give everyone a one time opportunity to buy one for their personal pump after which I will just be using them in the pumps I am rebuilding exclusively. I am sorry this has taken so long. 1st picture was the titanium plates we originally used to make the impellers the second picture is our new "grain correct" cylinders that we will be slicing to make ones moving forward
Bob
