How do they make several different HP tractors with all the other specs being the same?

mwemaxxowner · Jun 20, 2021

I've been trying to say this. Lol

If efficiencies are the same (and they should be on the same engine) and the only differences are tuning, the fuel usage should at least be similar at similar demands. There is a pretty cut and dry relationship between air and fuel usage at given efficiency levels and power levels. I can't begin to calculate any of it, I just know it is true.

WM75Guy · Jun 21, 2021

It happens in other applications. When we were at the Charlotte Motor Speedway in 1997 attending NASCAR fire/rescue training for working the races at Texas Motor Speedway we went over and watched the go-cart races. While touring the pits we talked with the mechanics, mostly the dads of the drivers, although some were professional team mechanics. They had to start with a stock Honda or B&S 5 HP motor. By taking the stock restrictor plate out between the carb and the intake they could get up to 60 HP. To make it last they had to switch out the pistons, rods, etc. to racing parts, both for weight reduction and to stand that much power. But the bore, stroke, and and other specs were still the same as the 5 HP engine they started with. They would hit 60 mph in the straights, no roll bar required at that time. Glad we never had go-cart races while I worked at TMS, only Lil" Texas for the Legends and Bandolero cars. They had full roll cages.

When I had to spec out a new Freightliner FL70 ambulance with a Cummins 8.3 for the fire department, the same motor was rated for 175 HP to 275 HP. The main difference was tuning, mostly the injector pump. Since the total truck weight was light and we had the governor set to 75 mph, we used 175 HP and still had to lock 6th gear out of the 6 speed Allison transmission. It would get to 75 mph in a hurry.