Pete.... it would be (i.e. area under torque curve = acceleration of torque) but only if the x-axis (absissa? or ordinate?) were in time based units... and they only "sort-of" are.... being that it's rpm, but the rate at which rpm changes is the time unit needed.
As an engineer, I've always found it interesting that the technical articles and information provided by the mfg'er never shows the maximum rate at which rpm can change in each gear... which is a complex (but definitely analytically determined) function of the cam intake and exhaust opening and closing rates & oroface's, cross-section of restrictions, pressure, & volume rate of input, and volume of the combustable material, gaseous volume at combustion temperature, & a bunch of other factors I am too ingnorant to devine... but all of which are part of the fundamental engineering design of an engine and it's ability to convert energy to revolutions of the crank --- given other loads on the crank and losses all the way thru to the drive wheel's (friction).
I know for a fact that the automobile industry (mfg'ers) know the analytic and empirical forms for the variants, since one of the engineer's I worked with designed the camshaft for one of the Ford racing engines 20 years ago... it was fundamentally limited by the stiffness profile of the shaft and cams with cam loads being continously varying per rev coupled with the resonant modes of vibration in the shaft itself with multiple vibration nodes and damping. Vary complex mechanical vibration displacements with all designs done by mechanical modeling. If, in my industry we can accurately model mechanical vibrations and modes to nanometers in the few nanosecond time periods, then it's a forgone conclusion that the automobile engine/drive-train designs are done with modeling at least as refined as those we use... and I'd guess a lot more (given the billions in annual revenue and competition in that industry).
Basically, all the torque curve (torque vs rpm) provides is the efficiency of conversion of energy to the crankshaft... peak torque being the most efficient point (in rpm units).... below that point the engine is starved for energy... i.e. could convert more per unit time than it's getting in energy input... and above peak torque the engine loses efficiency of conversion... I'm guessing, but probably because thermal gradiant's develop such that local points of heat energy can't be efficiently dissipated fast enough so local expansion's increase, which increase frictional losses... not to mention the vibrational nodes that develop within the cam, the rate at which the valves can open/close without bounce, etc.
If you think about it from an engineering standpoint, there's been quite an advance in energy conversion to the crank over the last 40 years... think about the torque developed in a new 230 MB sedan compare to the 230SL of our 113 vintage automobiles.... unfortunately, however, it's taken far too long to reach that state of efficiency.... since, in actual fact there was little to force the conversion until the Japanese entered the market place and began to sway consumers in the US and force the rest of the world-wide (read US and Europe) auto mfg'ers to tow the line.
Energy conversion can be taken as fuel efficiency, or as torque & hp efficiency per unit displacement..... or a combination thereof. ... so the US focused on using it to provide SUV's... read hp to drive greater mass/unit displacement. Interesting how virtually unlimited real-estate in the US allows larger, heavier vehicles to gain consumer's, while in Europe & Japan, with vastly limited real-estate and smaller older narrower streets in towns and cities (which grew from the days of buggies), the gain of consumer's interests is in smaller more negotiable vehicles, not to mention their higher relative costs of energy. Truth be told though, MB and in earlier years, BMW, Jaguar, Bently, etc. were the cars of 'kings'... i.e. the elite class of consumer that didn't care much about fuel efficiency nor size of streets in cities. As price of energy has risen in relative terms, so too has energy conversion efficiency improved in the automobile.... the economic balance always provides the incentives.
Longtooth
67 250SL US #113-043-10-002163
'02 SL500 Sport
