I'm talking about all of those huge v10 diesel turbo'd engines that pull huge F350 trucks and everything. Are they just built for torque? If so is there not a gear ratio you can put into the truck to crank all of those horses straight to the ground?

If those motors are only built for torque, what difference in the engine makes a car go fast rather than just pull hard and only go 60mph ?

Would a Bugatti Veyron pull a heavier trailer than your average truck? What's the difference?

Big truck diesel engines DO have a lot of torque, but this massive torque is produced in a very narrow RPM range... Usually between 1500 and 3000 RPM. That's why big trucks have lots of gear ratios in their transmissions, and up to 16 forward gears. The driver must keep shifting gears to maintain the engine speed at peak power and efficiency.

Automobile engines are designed with a wider power band, with most engines producing power between 1500 and 5000 RPM. Even then, lots of modern automobiles have 5 or 6 speed transmissions, to allow the engine to maintain peak power over a wide range of speeds.

While I am not specifically familiar with the Bugati engine, I would venture a guess that its engine is designed for high-RPM power, and that it does not have much low-end torque.

[EagleAutosports]

It's the length of the rods and stroke of the crank that makes torque, but they're so long that limits higher rpm's. They can't go very high without coming apart.

[4wheelsonline]

I have seen many drag race cars that don't have big truck engines. I think the engines depend on what type of car it is or the purpose. :P

[jydirect]

depends on the car being used, i guess..