Downsize HP's

This might be a stupid question...... The company truck that i drive is a single axle day cab 2004 t800 / cummins isx rated 450 @ 2000 rpm's... but the truck is governed at 1600 rpm. so is really putting out 450hp at 1600 ?

 

I don't know that I would count the pre-refined crude in the equation.
It's predominantly the temp of the processed fuel that needs attention.

I'm sure the degree of heating / cooling will change from region to region.

In areas like Florida, the fuel will never really cool down to the 60'F industry standard. The large tank farms use well insulated/protected tanks so when hot fuel gets dropped in, it never really cools. During transport, I doubt the fuel really gets to cool down before dropping it in an underground tank for resale. The resalers tanks never really cool down because the fuel doesn't stay in it long enough to loose the heat before another warm/hot load drops in.

In other parts of the country that stay cold or get cold for longer periods I'm sure there's an "evening out" of the non-compensation I'm addressing.

However, there's recently been a few lawsuits wherein T/S's lost the battle because it was proven that they were selling excessively hot fuels. Some were allowing their fuel heaters to remain operating continuously;Which they knew.

As you know, warm/hot fuel isn't quantity corrected at the pumps. Plus, you don't get near the "bang for your buck (btu's)" from hot fuels.

In the end, you didn't get all the gallons or the quality (BTUs) you paid for because the pumps don't automatically compenate/correct for fuel temps as it leaves the nozzles.

 

I have a D16 535hp w/410's and pull 139,000 lb loads all over Alberta, Canada and get 5 mpg.

 

Now when you say governed at 1600 rpm, do you mean in top gear? 'cause the last truck I drove (that had an ISX) would rev out in the lower gears, but in top gear it was governed between 68-70= roughly 1600 rpm in top gear.

So yes, the motor is making that HP, but it isn't all available (in top gear) 'cause the motor won't rev up far enough.

 

Alberta is not flat. I pull those loads up in northern Alberta up 6 &7% grades, and it is in U.S. MPG.

 

My boss when I was driving in England would pull our bonus if we ran less than 9 mpg, I could normally average about 9.6 the truck at the time was a scania R 420 cab over hauling a reefer trailer. max gross weight 44 metric tonnes.

I would have to do this on regional multi drop delveries in and arround major cities including London.

In my experience more hp does not allways mean less mpg, using a bigger engine you can shift at lower revs, skip change and use the additional tourqe to your advantage. I think another thing that helps with the economy is speed. UK trucks are limited by law and an electronic limiter to 56 mph. this is suposed to be the optimum speed. Because drag is directley proportionate to speed. each time you increase speed, drag increase 4 fold. ie double your speed and you multiply the drag by 4. this means more fuel is used to overcome drag the faster you go.

so with this in mind tuck manufacturers in Europe normaly design the torque curve of an engine to be long and flat. IE it produces max torque over a wide low rev band with out peaking. this enables up shifts to be completed at about 1100-1390 rpm ( normaly marked with a green band ) and the truck is geared to run at 56 mph in top gear within the green band. see tourque and power chart

so I gues what Im saying is its not the engine size that matters most, its the way you drive it. and big power does not allways mean less mpg.

I also believe that the UK imperial galon is slightly larger than a US Galon ( one thing that not bigger and better in America ) so that would have an influence on Uk trucks average of 9 + mpg. but not to much. its mostly down to the driver and speed.

The trick is to maintain you rpm between in the scania's case 1100 and 1390 the flat band of max torque on the graph, this is the rev band marked in green on the scanias rev counter. " stay in the green keep it lean "

 

9 mpg UK = 7.5 mpg US