Engine testing has always been critical. Trish Yunick
Once individual cylinder timing is optimized, it's then a matter of examining air/fuel charge optimization on an individual cylinder basis. A frequent procedure for performing such evaluations involves O2 sensors placed in proximity of the cylinder heads (as you might locate for traditional exhaust gas temperature sensors). By the use of these type sensors, depending upon the method of fuel delivery (carburetion as opposed to individual fuel injectors), the specifics for providing optimal air/fuel charges on an individual cylinder basis will vary.
For example, as compared to the time-honored EGT method, O2 sensors look more at the combustion process itself than the temperature-based results of the burn. Generally, especially if the engine uses a multi-point EFI system, this particular step is made much easier than when either making internal modifications to a carburetor intake manifold, utilizing "mechanical" fixes in the manifold.
Of course, you can also explore multiple valve timing variations through camshaft lobe design and positioning, but here's an area previously discussed in this column that probably doesn't need repeating.
But let's step more into the combustion efficiency evaluation techniques we'll be using at MTU. In this instance, we have the best of several worlds. By collecting virtually real-time cylinder pressure as a function of incremental crankshaft angles, on an individual cylinder basis, we'll have a precise look at how cylinders are pressure-balanced, along with determining the cylinder of highest pressure which, in turn, sets the pressure bar for the level we'd like the remaining cylinders to achieve. Plus, since we'll have control over individual cylinder spark timing (optimization) and fuel delivery, following the so-called "2-3 horsepower gains at a time" approach, the chances for overall power optimization are further improved.
And don't forget, we'll be doing this while comparing conventional racing gasoline to our chosen E85 fuel. Since the project has already demonstrated that E85 (coupled with EFI) is superior, on-track, to the carburetor/gasoline combination, our focus will now be more toward optimizing the package for E85.
Lofty expectations, you think? Actually, while this presumably "academic" approach to optimizing the G.R.E.E.N. engine's combustion efficiency may seem like a reach, it's intended to push the thinking of CT's readers. From the beginning, this project was designed and intended to provoke new thoughts.
Racing has never been a stagnant landscape, at least for racers who are successful. The time is pretty much gone when "chunks" of horsepower could be carved out with relatively simple and obvious modifications. Obviously, there are those who would argue that it's the skill and chassis setup and driver skill that produces a competitive edge. And, even as a died-in-the-wool mechanical engineer who believes such an approach produces winners, it's never a disadvantage to have power in reserve when you're exiting a turn or passing the flag stand.
Properly matched power and chassis combinations work, and if you fail to recognize that adapting to changing technologies and the opportunities to be gained from them, you could become a victim to a quote I again attribute to Smokey; "If you ain't thinking, you probably ain't winnin'. Copying hardly ever works."