4. Wideband O2 Meter
A little over 15 years ago, if you wanted to accurately measure the real-time air/fuel ratio (AFR) by content of oxygen in an exhaust stream, it would cost you around ten thousand dollars for the equipment. A more popular and economical approach was to independently measure the intake airflow and fuel flow, and compute the resultant AFR-although outside of the dyno cell, this was highly impractical. Thanks to advances in sensor and meter technologies, modern units can offer superior accuracy and be had for only a few hundred bucks. Because of its high-benefit-to-low-cost ratio, the modern wideband is not only a top ten tuning tool, it is a must-have tuning tool. Widebands are used as feedback devices, delivering a quantified measurement of an engine's nearly instantaneous ratio of air and fuel consumption. The wideband's output is typically conditioned to display the AFR or an equivalency ratio, ER (ratio of actual to stoichiometric). For gasoline engines, the typical target for AFR during light load and cruise is around 14.7:1 (1.0:1 ER), or 14.7 parts of air for every 1 part of fuel-the corresponding stoichiometric ratio for the chemical reaction of gasoline combustion in air. Under load, naturally aspirated engines typically make peak power around a richer (more fuel) AFR of 13.0:1 (0.88:1 ER). Forced induction engines require a much richer ratio yet, sometimes going as rich as 10.0:1 (0.68 ER). These targets are used to set fuel delivery maps appropriately. By sampling the AFR at each operating point, a tuner can adjust the commanded fuel delivery at point to result in exactly the desired AFR.
5. Exhaust Gas Temperature Meter
Exhaust gas temperature (EGT) meters are one of the most widely overlooked tuning tools available, despite being one of the simplest and most effective. EGT is widely known as an effective and inexpensive means to monitor every cylinder's status. Things such as failing valve springs, faulty injectors, and leaking head gaskets are easily spotted through EGT readings. Turbo tuners, like Cal Hartline of Hartline Performance, also rely heavily on EGT for their measurement of a turbo's available and consumed energy, and because unlike wideband sensors, EGTs will survive in the incredibly hot environments around turbos. Hartline uses EGTs both in individual cylinder runners and around his turbos. On his race tunes he'll see temps as high as 1700F in the primaries-well beyond the safe range of AFR sensors. Much like the evolution of widebands, modern EGT probes and meters are now economically attainable and practical for street use. EGT is also proportional to AFR within functional tuning ranges; leaner mixtures cause higher EGT and richer mixtures cause lower EGT. By monitoring AFR with a wideband in one cylinder's primary and equipping all the primaries with EGT probes, it's then possible to extrapolate the approximate AFR (using the correlated relationship measured between EGT and AFR from the wideband equipped primary) of each individual cylinder based on its respective EGT reading. Beyond use as a tuning tool, EGTs can serve other functions too, such as evaluation of exhaust components or even engine components such as camshafts or intake manifolds.
Old Bridge Township's Raceway Park is the preferred proving ground for GMHTP tuning, along with sister Primedia mags. Besides being a great tool, as a place to legally 'throw down' and speed, E-town is generally packed with fellow and knowledgeable tuners. |  |
There is no easier way to get a peek inside your tailpipe than with F.A.S.T.'s trick dual-sensor wideband air/fuel meter (pn 170402, $613.27). The F.A.S.T. unit is plug-and-play, with an easy to use interface. The uniquely 'blue' backlit LCD display is equally easy to view in daylight and at night. The unit is available as both a single (pn 170401, $466.60) or dual sensor kit-with various cable lengths to suit all tuners, dynos, or motorcycles. The easy self-calibrating operation allows users to accurately start metering exhaust as fast as they can plug the unit in. F.A.S.T.'s meter has a stand-alone, built-in data-logger as well, to enable recording for future review. For advanced tuners, the F.A.S.T. unit can be configured to output an analog signal for use with other tuning tools or control systems. And with two sensors operating, the box can do a few trick things, like average both signals together. In F.A.S.T. fashion, the units ship complete, including a hard plastic storage tote and a detailed instruction manual. There is more on the way, too. A discussion with F.A.S.T.'s Jay Rohrback and ZEX's Matt Patrick tipped us off about an optional new rpm module (170536) that will allow indexing the meter readings with the exact corresponding rpm. Ron Turnpaugh, F.A.S.T.'s electrical engineering whiz, also mentioned he is hard at work on a new 'E85' (an 85-percent ethanol, 15-percent gasoline mix) version to complement the existing meter's gasoline and methanol calibrations. | |