Typically, an encoder is attached to the crankshaft snout, from which incremental crankshaft positions (in degrees) can be determined, relative to piston position. In order to examine small but finite crank positions, it's possible to create increments as small as fractions of a degree. At very high data sampling rates, this approach enables a virtual "real time" flow of information. Then, within the cylinder, high-rate pressure transducers record cylinder pressure variations that are specifically linked to crankshaft position. So, as a function of crank angle, it's possible to tie specific cylinder pressures with equally specific piston positions relative to crank position.
As a result, it's possible to record and evaluate any pressure changes that occur in the combustion space at a very high rate of recording. Further, since we know that net cylinder pressure is the primary ingredient to producing crankshaft torque (computed as horsepower by including time), the study of what we're calling "real time" combustion pressure history provides a targeted look at the foundation of combustion efficiency and its effects on power.
More importantly, since we're dealing with what could functionally be called a "single-plane" intake manifold (all runners joined in a common plenum volume), the net influences of reversion pulses and other pressure excursions that are both normal and unavoidable in such a design can be examined. To do this requires all cylinders (combustion spaces) be fitted with pressure transducers linked to the crankshaft's encoder device. That's exactly what will take place in our G.R.E.E.N. engine while at MTU.
Now, why is this particular exercise of value to the project? Primarily, it's because we can determine more than cylinder pressure histories vs. angular crankshaft positions. By applying certain thermodynamics calculations and related computations, we can develop cylinder pressure vs. cylinder volume, as each changes (relative to the other) throughout complete combustion firing cycles. And by calculating the first derivative of the pressure/crank-angle equation, we can also evaluate the rate of cylinder pressure change. Also as a function of crankshaft angle, we can estimate the rate of combustion heat release, if we assume that heat transfer (and leakage) to the cylinder walls can be neglected. Not a problem.
It's also possible to create a graphical trace depicting combustion space temperature (again as a function of crank angle), notably from the time of intake valve closing to intake valve opening; a data stream that includes peak combustion space temperature that is generally just past TDC on the power stroke. Even though we may elect to perform similar calculations beyond these, we'll make certain to convert the rate of heat release data to a percentage of air/fuel charge burn which will allow us to define the length of the burn, time to fully develop combustion and ignition delay...all critical elements in the study of what transpires in the combustion space.
Since part of the project (by design) involves fuels that are alternatives to racing gasoline, it's reasonable to assume that such fuels may have different combustion characteristics. That's patently fundamental. However, ECA will allow us to not only quantify the different characteristics but also provide information that can be linked directly to modifying or designing "alternative fuels" hard parts like cylinder heads, intake manifolds, piston crowns, camshafts, and (very likely) ignition systems. It's projected that by analyzing specific combustion characteristics of the various fuels to be evaluated, windows of opportunity will be opened to parts manufacturers seeking to match hard parts with the use of alternative fuels.
This collection of thoughts and information is just a preamble to what we'll share with you a few months from now. What's important to recognize and keep in mind is that this pioneering project is dedicated to creating an awareness of what may, or should, be included in the future of circle track racing in particular and motorsports in general. The fact that you're reading about and following this particular initiative is a credit to your hope and belief in our chosen profession or avocation. Clearly, the readers of this magazine are at the core of what lies ahead and any comments you'd like to share are more than welcome. In the end, isn't it all about "what if"...?