i know this is a funny old question.. but was just wondering how much weight there is in a full tank of full compared to say quarter tank.
is fuel heavy..? would you get better consumption because of less weight if you just ran around on quarter tank max.
i know in formula one fue lload/ weight seems quite critical but then again their fuel is probally quite different anyway
is diesel heavier than petrol?
Lets say a full tank is 70 litres. If that were water, that would be 70kg. However, fuel (diesel and petrol) is lighter, and the actual density can fluctuate with temperature.
The density of diesel fuel oil at 15 degress Celsius is 820 to 950 kg/m3. In other words, it has from 82 to 95 percent the density of water, or specific gravity (relative to water) of 0.82 to 0.95.
So if we take a mid point of 0.88 x 70 = 61.6kg of diesel on a full tank.
Petrol is lighter still, with a Specific Gravity (SG) of approx 0.71-0.77.
Using the same formula, and taking 0.74 x 70 = 51.8kg of petrol on a full tank.
I hadn't realised there was such a difference until I just did those calculations myself - not only is a diesel engine itself heavier, but the fuel is 10kg per 70l tank heavier!
In theory, running on only a quarter of a tank would save approx 45kg of weight (diesel) - half an adult passenger (ish). I'm sure this would increase economy by a certain percentage, but I think it would be negligible over the course of a tank, as the weight is decreasing anyway with fuel burn.
Can you tell I didn't have much to do today...