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A'PEXi S-AFC Engine Management - Dyno Cell

Super AFC Digital Meets A Lexus Is 300

Arnold Eugenio
Jul 1, 2001
Photographer: Arnold Eugenio
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Turp_0107_02_z+apexi_safc_engine_management+lexus_is300_front_right Photo 1/10   |   A'PEXi S-AFC Engine Management - Dyno Cell

APEX Integration burst onto the scene a few years ago with the goal of introducing high-quality race-bred street parts at affordable prices. Since hitting the scene, the company has flexed its technological muscle in the arena of electronics. An example cutting edge of technology is the Super AFC Fuel Computer. In this third generation of upgrades, the AFC has gone digital. This means not only that the knobs have disappeared, replaced by soft-touch directional keys, but also that the incoming information and outgoing calculations happen millions of times faster. This faster processing speed translates into more accurate and precise control of fuel-related events, and, combined with diligent tuning, a faster and more reliable ride for the end user.

The APEXi S-AFC is housed in a silver case that is 1/2-DIN size. The display screen is relatively large, well-lit and easy to read-even under the most spirited driving conditions. Illuminated by an eclectic blue-green Vacuum Fluorescent Display (VFD), the the unit would complement any interior.

Turp_0107_03_z+apexi_safc_engine_management+is300_engine_bay Photo 2/10   |   Our IS 300 tester's 1JZ-GE has been lightly modified with a high-flow intake and cat-back exhaust system. We have employed the APEXi S-AFC to extract maximum potential from these typical bolt-ons.

Functioning as a meter display, the S-AFC does cartwheels around the competition. Three modes of display can be shown on the screen: "Numerical," with it's real-time adjusting numerals; "Analog," which imitates two small gauge faces with needles; and "Graph," a running bar graph of under-the-hood events. Using any of these modes, the user can actively monitor intake manifold vacuum, intake manifold pressure, air flow capacity, engine rpm, throttle position or airflow correction percentage factor. All of this information is pertinent to the driver that wants to know his engine, not blow his engine.

At the heart of the S-AFC's magical powers is the ability to control fuel delivery at eight rpm points throughout the powerband, offset in increments of 500 rpm. This precision control allows the user to add (or subtract) fuel where needed. The advantage of an electronic fuel control system vs. a manual one (such as a high-pressure fuel pump or larger injectors) is that it allows for precision tuning where it's needed. In addition, the S-AFC can help tame the rough idling, poor fuel economy and erratic power delivery of engines with upgraded larger injectors and high-flow fuel pumps.

All of this is done electronically through the vehicle's factory airflow meter or MAP sensor. The S-AFC jumps in line at the vehicle's ECU, where it takes the reading coming from the ECU, recalculates it according to a percentage difference set by the tuner, and then sends it back to the ECU which tells the fuel system to compensate accordingly. It is a simple and logical technology, and we wanted to see how well it works.

We took an S-AFC to Nacho Negishi at Dynamic Autosports in Lake Forest, Calif. and set up a blind date between it and a slightly modified 2001 Lexus IS 300. The IS 300 is a "new classic" stateside, now that our market has finally been blessed with its own version of the Toyota Altezza "wnderkar." Nacho happily and easily conquered this first-time install as soon as he found the ECU, which was hidden in an air-cooled box in the engine bay. The S-AFC was very easy to install with the included car-specific wiring diagrams, including pin locations and a minimum amount of connections.

Turp_0107_04_z+apexi_safc_engine_management+rpm_bar_graph Photo 6/10   |   A'PEXi S-AFC Engine Management - Dyno Cell

The Dyno Cell
With the S-AFC in place, the keys were handed to master tuner Aries Dizon, who strapped the car to the dyno and prepared to outdo the Lexus engineers. Whether you hold the viewpoint that the IS 300 is a highly engineered piece of machinery that doesn't need much else, or the position that the addition of an aftermarket intake and exhaust system sufficiently changed fuel demands to warrant fine tuning - either way you look at it, the S-AFC worked wonders. It shifted the entire power curve upward throughout the tested powerband, with a low median gain of 6 to 8 hp and maximum gains of about 13 to 14 hp. The maximum power output jumped from 166.8 to 176.0 hp turning the rear wheels. The torque curve naturally followed the same order, with an even gain of about 10-12 lb-ft across the mid- to high-speed portions of the powerband.

Turp_0107_06_z+apexi_safc_engine_management+apexi_unit Photo 7/10   |   A'PEXi S-AFC Engine Management - Dyno Cell

Digital fuel control is here to stay. No more tinkering with carburetor jettings, no more dangerous guesswork with upgraded injectors or high-flow fuel pumps, not to mention dubious pressure-sensitive regulators. The APEXi S-AFC makes all of this obsolete. Since the S-AFC modifies the ECU signal instead of replacing OEM fuel components, it can be used on a wide variety of applications. From mildly tuned, daily-driven vehicles (like our test bed IS 300) to weekend drag warriors with turbos or nitrous, the S-AFC can benefit them all-no car has too little or too much.

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By Arnold Eugenio
2 Articles

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