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.

I will do the test as well, I might be off of course becasue I am running a diesel. I will also get it in .1L

I do know my car idles warm at 925 rpm at .25L or .066 gph

0.066 gph :o

So, if someone was pushing the car at 3mph, you would get 45mpg with the engine idling :)

landspeed, great job last week. Will you do the fuel useage test on your car?
I am gathering info, thinking of a turbo. If you can, match the rpm numbers that I did. Thanks

Except that it will hold 5th gear at idle, about 28 mph.
Calculate........NOW!

Double check your numbers since it can't possibly be correct.....now!

:eek:

CO ZX2:
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.

CO ZX2 : I don't have an instantaneous MPG meter yet, but will do those tests once I do!. I also need to fix my AFM as it is running a bit rich again :(

Lug_Nut : The 0.066gph sounds reasonable for some cars. In fact, I was using a work car yesterday with instantaneous MPG - it was a diesel, and at 10mph, the MPG goes >90.0 (if idling and coasting).

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.

0905 rpm .0528 (.13) gph
1000 rpm .0752 (.18) gph
1500 rpm .1585 (.29) gph
2000 rpm .2906 (.37) gph
2500 rpm .5046 (.50) gph
3000 rpm .7397 (.66) gph
3500 rpm .8189 (.77) gph
4000 rpm .9774 (.93) gph

So it looks like once I get above 2500 rpm I start to loose overall efficiency compared to a gasser?

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
1000rpm .44gph
1500rpm .63gph
2000rpm .83gph
2500rpm 1.07gph
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.