Gadgetory

okay aside from emissions and heat the two big outputs of any engine are horsepower and torque you know all about the first one you've heard about it since you were a little kid it's in every automotive advertisement everything the automaker has ever talked about has horsepower in there somewhere but torque as far less well understood though extremely important let's break them down and define them first horsepower is a measure of work its definition makes that obvious one horsepower is equal to 33 thousand foot-pounds per minute now torque is also a measure of work but it describes work as twisting force it's kind of like horsepower in a circle and without the per minute factor torque is measured in foot-pounds not a certain number of them though for example it may take 27 foot-pounds of torque to loosen a particular bolt on this engine without regard for how long you have to apply that force so at the risk of oversimplifying horsepower expresses how much work you can get done in a certain amount of time torque is about how hard you can twist something and that's key because how does a car move itself the engine turns it twists the gears in the transmission they twist output or drive shafts and that moves the car torque really should be the star okay seriously let me show you on some charts how horsepower and torque work I promise you won't fall asleep now these are charts from cars have been put on dynamometer is basically treadmills for cars you've seen these our partners over at Edmunds do a lot of kind of testing and gave us this data and it's very instructive here's a 2011 Ford Mustang here's how the chart works on the Left you've got your vertical axis of either foot-pounds of torque or amount of horsepower down across the right is basically your tachometer its rpms from 1 to 8,000 in this case now look what happens the torque line is this light blue one you start building around 2,000 rpm and you got more and more torque as you increase the revs you peak right around here at about Oh 4200 with 365 foot-pounds all that engine has and you stay at about that range until around 5200 rpm this is the sweet spot this is where you've got peak torque that just keeps coming after a while more rpms the torque begins to drop horsepower keeps increasing let's look at another car here's a very different engine in a McLaren mp4-12c supercar here's our torque line again builds gradually and then notice that about 4200 all the way out to about 6200 this guy stays flat and right about at the peak amount of torque around 415 foot pounds this is a wider what they call fatter torque band you've got more rpms where you have full torque from the engine mercedes-benz s63 instructive because this is a twin-turbo v8 look what happens with turbos this is the torque line it's out of hand it Peaks really fast and it stays broad chunky and 611 foot-pounds of torque that's a lot by the way for a very long time before it begins to degrade and finally a very different car a Scion fr-s Peaks here early at only 143 foot-pounds of torque but then look what happens you get this dip here if you ever hear me driving a car and say I feel like there's a flat spot in the torque curve that's what I'm talking about it's not flat at all it's actually a dip where the car feels kind of gutless and then up around 4800 rpm it kicks back in again and stays nice and flat all the way out to the mid 6,000 now you may have noticed in all these charts torque tends to peter out as you get to the higher rpms up near your redline that's because the engine is less able to breathe efficiently there secondly notice that horsepower keeps climbing even after torque drops off why is that seems like it's two engines doing different things well even as torque drops off the RPMs keep climbing and horsepower is largely a product of rpms times torque so we can put those two together and keep that horsepower line moving up because torque is dropping but only modestly as our PMS go up in a linear fashion okay I hope you've got a better understanding now of horsepower torque the relationship and how they impact the driving experience of a car also note we do our car videos I'll show you those two numbers and horsepower is usually the bigger torque is often the smaller unless that car has a turbo or a supercharger which artificially puts more in the engine and allows the torque to come higher or as high as the horsepower that gives you another clue as to what that car is going to be like to drive