I thought my battery was fairly well-charged but was still showing around 14.5 volts when running this test.
That is normal. It is necessary for the alternator to be at a higher voltage than the battery (13.2 for a six cell Pb-A) for current to flow. The question isn't how much voltage, but how many amperes? The amperes are a better indication of the actual load on the belt,(and drag on the engine) since the voltage regulator will keep the charging voltage at right around 14.4 and the amperes are allowed to vary.
The much lower gph figures in your rpm tests are probably due to your 10,000+ft elevation. The air is a lot thinner up there, so the engine controller needs to add less fuel to that thinner air to maintain the correct air/fuel ratios.
It's not necessary to keep down to a jogging speed or slower for better F.E.
I averaged 83 mpg (2.8l/100km) at (barely) highway speeds over a 250+ mile course in the 2003 Tour de Sol. The proscribed course simultaneously tested both fuel efficiency and range. An average of 47 mph per loop was the slowest I could go to get credit for the loop distance.
The 2005 Tour de Sol had a competitor's choice of course with the requirement of a finish at the event site and a minimum of 500 miles distance. That year the car got 77 mpg (3.3l/100km) at an average of 42 mph.
My present onboard display frequently indicates 99.9 mpg, its display limit.
Diesels don’t like high RPM’s Here are my result with a warm engine. This really makes me want to do the 5th gear swap (swapping it for a gear 11% lower) at idle I sit at 905 rpm, can’t get below that. I put (CO ZX2) for reference.
I went back and checked my consumption at different rpms. I was concerned that my readings were not accurate enough last time, so I made sure the radiator fans were off this time. There were no other loads on the engine. I held each rpm point as steady as possible while I took the reading, which was about 15 to 20 seconds. In between each rpm point I let the engine idle with both fans on.
Idle 720rpm .34gph
These are slightly lower than my first reading, which were done on a warm afternoon. Maybe the fans were coming on? Either way, this shows me the base consumption for my motor.
CO ZX2 wrote:'How much boost do you see at 2000, 4000 and max boost? I have given some thought to a turbo for Old Reliable. Trying to get some ideas.'
I've never really looked at boost around 2k rpm. I might see 5 to 8 psi around 2k. The turbo hits max boost of 20psi around 3200 rpm. To give you an idea of the powerband, redline is 7k, peak HP is somewhere around 6200rpm, peak torque is somewhere around 3800rpm. So if you're looking for a turbo, check that the turbo flow matches your motor. I have more info if you need to know more.