If you want rpms and horse power, build a short stroke gas motor. If you want torque, the ability to actually do work, and a fuel that is optimized in a motor like an eco diesel to run at 1900-2000 rpm's, all day long, to haul the load, or run around empty and get exceptional open road high MPG's, build a long stroke small block turbocharged diesel.
If you have to haul the load, look at power plants in boats, locomotives, and big rigs, where the heavy work needs to be done. All diesel power plants. There's your sign.
I don't race my truck, therefore, I don't want or need a gas motor. The price differential to me for diesel versus gas is insignificant.
The only thing I would do is limit the amount of work, weight wise, I would expect out of a 3 liter motor, to about 65% of the max payload allowed... 50% would be better, with a travel trailer.
A longer stroke will always allow more work to be done for the amount of fuel burned... it's identical to having a longer barrel on a high powered rifle allowing more time for the powder to burn and propel the bullet faster, for the amount of fuel burnt. It does more work, on the same amount of fuel, at a lower rpm. When you are doing a lot of work, it is all about efficiency. Turbo diesel's are flat out, more efficient. Smaller block, less pistons, and less parasitic losses from the engine block /pump, equals higher efficiency.
