Hi,
You stated that both would have roughly the same amount of "Torque".
It is torque X RPM's that make up horsepower. So despite that gas engines now typically have less torque than a diesel, they make as much horsepower due to their ability to turn 5,000 RPM for long periods of time on a test bench in a lab.
While I have run my 460" motorhome engine at 4,200 RPM while climbing a mountain, it has a longer stroke and probably should not run that fast a long time. The much smaller pistons in a 5.4L or 6.8L v10 would be happy running 4,200 RPM for 5-10 minutes at a time, even go to 5,000 RPM for a minute or two. That engine is designed that way.
The reason Ford went with a V8 configuration in the trucks is it can run higher RPM's than the straight 6 diesels that Ford has built for over 80 years. Even back in the 60's Ford teamed up with Caterpillar to build the Ford 636 diesel, a V8 that was not turbocharged. Later turbocharged engines where much more powerful, but Ford wanted something to put in their class 7 and class 8 trucks besides the normal inline 6.
So given you want to "Race" a early 7.3L diesel engine with a lower factory torque rating to the later versions of say a 6.8L gas engine with about the same torque rating, and yet much higher RPM ability, yes the gas truck will run to the top of the mountain faster. Or of you like to compare GMC's, then take a 6.2L diesel and run it against a 350" gas engine, and the gas engine will win all the time, due to higher HP rating.
However if it is a contest to run from Los Angeles to Las Vegas, and both have 35 gallons of fuel, and any fuel stop requires them spending 35 minutes at the fuel stop, then the diesel can win that "Race" by taking the hills a little slower and saving fuel. Running a little faster on the level and downhill sections will not cost to much fuel, and will save time overall. The extra minute you spend at 45 MPH going up the two or three major mountain passes will be made up in time saved buying fuel.
Fred.
