There’s a glut of air-fuel ratio meters on the market, and picking the right one for you and your car is not an easy task. FAST realized during development of its latest FAST Air/Fuel Meter that it could not build a tool that would work perfectly for every street and race car, but they could build a unique meter that would work great for a wide variety of enthusiasts. After seeing a FAST meter in a few carb’d street cars at our local track in Irwindale, California, we decided to ask around and see why it was so popular. This story is a result of that research.
The FAST Air/Fuel Ratio meter has two unique features that make it uniquely appealing to a carb’d street/strip enthusiast. First, it has on-screen data-logging vs. RPM that does not need a laptop to play back the quarter mile runs. Second, it is one of the only meters on the market that has a “Dual Sensor” feature to record the air/fuel ratio for each side of your engine. That makes carb tuning a much more accurate process for troubleshooting a poorly tuned engine.
We began the process of finding a car in a poor state of tune, and it wasn’t long before a friend found this 1972 El Camino with a Chevrolet big-block under the hood. It hasn’t been tuned at all by the owner and was running poorly with a new carb. It was a perfect time to demonstrate the FAST Air/Fuel ratio’s built-in logging and see how it worked in a real-world application.
Here is the plan: First, install the FAST Wide Band Air/Fuel Ratio in the powerTV Garage on the 1972 El Camino. Take it to the track and make some basline runs while logging the air/fuel ratio. Then, re-tune the Edelbrock carb using that logged data within the FAST meter, and make more runs. Hopefully (fingers crossed) we see some improvement. It will all depend on how poorly tuned the wagon is before we start wrenching. Then, we take it back to the PTV garage, put in the baseline tune, and make some dyno runs. Follow up dyno runs will be performed with the “after dragstrip tune”. This will tell us how much power our tuning with the FAST Wide-Band actually gave us. Cam Benty from COMP Cams got the call to help with the install and testing, but first, we need to start with the….
Basics of a Wide-Band A/F Meter
Finding that sweet spot for maximum horsepower all starts with optimizing how lean or rich your engine is running to achieve an optimal air to fuel ratio. Whether you have a naturally aspirated engine or a boosted engine, there will be an optimum air/fuel ratio that produces maximum power in a safe window. For a naturally aspirated engine it might be 13:1, and on a boosted application 11.5:1, for example.
Now, on an engine or chassis dyno, you usually have the ability to see your air/fuel ratio on the dyno’s computer and adjust accordingly. Your tuner (or you) can adjust the EFI or carb to maximize measured power. For example, powerTV’s Dynojet has a built-in wide band and so we use that resource for each and every vehicle. However, you don’t race on the dyno, and various factors from temperature, to load, to altitude will affect your vehicle’s air/fuel ratio while running at full throttle on the street or strip. That is where an air/fuel ratio gauge comes in.
FAST’s Wide-Band Dual Sensor Air/Fuel Meter
Let’s take a closer look at the FAST Wide-Band Dual Sensor Air/Fuel Meter. First off, everything is included; the FAST digital display, wiring harness, hardware, and instructions, and it’s available in both a single and dual sensor version. The kit includes:
- FAST Wide Band Digital Meter w/built-in calibration and quick-start mode to deliver A/F ratio within 1 minute.
- Weld-in threaded sensor bushings
- Wide Band O2 sensors (1 or 2)
- 6 foot Power Cable
- 12 foot 02 Sensor Cables
FAST’s Ron Turnpaugh believes the unit is perfect for the do-it-yourself carb tuner. “The FAST meter is a good tool for a home tuner. It allows you to find inconsistencies in your car, such as a misfire or vacuum leak, and it’s a great tool for safety. You’ll actually be able to see if there is something wrong with your fuel supply, or even a dirty air filter. It’s a great troubleshooting device.”
Turnpaugh told us the FAST meter is unique in that it doesn’t require any external laptop. “The FAST meter plays the air/fuel ratio log back right on the display, so you don’t need to bring a laptop and any other interface with you. It’s a complete stand alone air/fuel meter with complete data-logging, and you can tune your car accurately and repeatedly.”
Additional features Ron told us about include outputs for external data loggers and gauges, and a narrow-band simulator function that allows you to feed your engine’s computer a factory signal while using the wide-band sensor for air/fuel measurement and adjustments.
The Choice — Single or Dual Sensors
One of the things you’ll need to decide is whether you want to get the single or dual sensor version. The single sensor is a good starting point for the first-time A/F meter buyer, as the FAST Display allows you to upgrade later to the dual sensor if you so choose.
“The unit you are testing is our dual wide-band unit which allows you to measure two different channels at the same time, usually the right and left banks of your engine,” explained Turnpaugh. “Then, the two sensor meter really helps you pin point any sort of inconsistencies in your engine’s air/fuel. Basically, it helps you find out if one side of the motor is lean or rich and helps you troubleshoot your engine very accurately.”
Installing the FAST wide-band dual sensor requires only a few tools and some basic mechanical knowledge. The major steps are removing the exhaust, welding in the 02 bungs, the wiring, and mounting the FAST meter on your dash or window. Let’s review the basic installation photos.
We began by removing the stock exhaust from the El Camino. It has a dual 2.5-inch exhaust with an X-pipe. Since we were installing the dual FAST Wide Band, we felt removing the x-pipe would make installation of the 02 sensor bungs easiest.
We installed the provided FAST 02 sensor bungs in the 2 o’clock position on each side of the x-pipe, only 5 inches or so from the header collector. FAST recommends installing the sensors no lower than 3 o’clock or 9 o’clock to prevent the sensor from getting water damage when there is condensation in your exhaust pipes (happens overnight generally).
For maximum accuracy, we installed the oxygen sensor just upstream of the catalytic converter. You can install the sensor after the converter, but the readings will register slightly leaner than if measured before the converter. We marked the spot on the headers to install the threaded sensor bushing and drilled a .750-inch diameter hole and welded the bushing centered on the hole. After we threaded the sensors into the bushings, we attached the cable’s sensor connector to the oxygen sensor and then routed the cable to the interior of the vehicle. The meter plugs into the cigarette lighter to power the digital display. The last step was to plug in the sensor cables to the side of the display housing.
Once we got the wiring done, it was time to install the FAST display. There are a number of mounting options for the FAST Wide Band, but we employed FAST’s optional window suction mount, which allows you to stick it to any window in the vehicle. Here you can see we used the side glass. Once mounted, we powered up the FAST Wide Band Air/Fuel Ratio Meter by plugging it into the cigarette lighter. It powered up within a few seconds and we began a very simple setup process.
The first screen is a setup process where you can select what type of metering you want to do. There are options to view each sensor individually, view them together, or a single reading that averages both sensors together. Basically, you can read two sensors individually or average together for more accurate readings of the engine’s true air/fuel ratio. Since we were running a gasoline setup, and wanted the true individual dual sensor inputs, that was what we selected.
Now it was time to head to Irwindale Dragstrip.
Phase 1 – Tuning at the Track
With the FAST Air/Fuel Ratio Meter hooked up and glowing a beautiful blue hue, it was time to head to Irwindale Dragstrip, an 1/8 mile NHRA sanctioned facility. The weather was fair with a temperature of about 85 degrees, much warmer than back at the powerTV Garage! Our objective here is to run the car in the original un-tuned state and record the AFR to see how the current conditions affect the car’s performance across the finish line.
We knew the El Camino was poorly tuned, as it blubbered back in the powerTV garage both at idle and during a few random street blasts. With street tires, we did encounter mild wheel spin off the line; however, we didn’t know how poorly tuned it really was. After a few burnouts and warm-up laps to make sure the suspension was going to help the truck go straight, it was time to let the ‘Camino stretch her legs with a full 1/8 mile.
We staged the El Camino at 3,500 rpm and could hear the big-block roaring as we prepared to dump the clutch. 60-feet into the run, we were wondering where all of the power was. Not only did the big block feel lazy, but it revved with the speed of Barney the purple dinosaur. We didn’t need the time slip to know that the El Camino was a potential victim to a hopped-up Honda – not where we wanted to be. However, the time slip did provide an E.T. for us – 9.48 at 83 miles per hour, which corrects to a high 14-second run at 103 miles per hour. No matter how you cut it, that’s awful for a big block powered classic Chevrolet with a nice engine, even WITH street tires. We did have some traction issues off the line, having to feather the throttle, but even the MPH was low.
With a return to the pits, we eagerly pulled up the logged air/fuel ratio data. Not a surprise – the ‘Camino was pig rich, with an AFR ranging between 11.2:1 to 10.8:1. Because we used the RPM module, it logged the RPM as soon as it was revved so there was no need to turn on the meter. The rich condition was because the Edelbrock carburetor that is on our El Camino is straight out of the box and hasn’t been tuned at all, so it was pretty much a guarantee that the car was out of tune.
Our strategy was simple; lean the Edelbrock carb out. Using the jets and metering rods, we made a fairly substantial change decreasing the calculated fuel metering 7% based on jet volume. We also tried to lean out the Edelbrock carb at idle and off-idle because we were rich even in these conditions. If you are interested in a good article on tuning the Edelbrock carb check out this article in Mustang & Fords magazine.
Once we fired up the big block, immediately our idle was cleaned up and some seat of the pants revving indicated a much better air/fuel ratio. Even at idle, we were now seeing air/fuel ratios in the mid 15’s, which is ideal for a non-loaded situation. Prior to tuning we saw air/fuel ratio’s in the 12’s at idle, a very fat condition. After a few runs, we were rewarded with a substantial improvement, an 8.38 at 90 mph, an increase of 7 miles per hour, and over a second drop in E.T. Now, air/fuel ratios showed low 13’s, a great place to be for a naturally aspirated street car. In the interest of full disclosure, 60-foots did improve about a tenth, due to increased track temperature, but even removing 1.5 tenths from the equation (8.53 estimated 1/8 mile) that is still an improvement of a half second in the 1/8 mile alone.
Obviously, the FAST Air/Fuel Ratio meter was not responsible for this performance improvement. However, it proved to be an important tuning tool that helped us get the Edelbrock carb tuned correctly to provide the correct air and fuel mixture to the big block. The end result? A big horsepower increase and dragstrip performance improvement.
Dyno Testing the Improvement: What was Tuning Worth?
Back at the powerTV garage, it was time to see what the before and after dragstrip “real world” tune up was worth. Since both the elevation, temperature, and atmosphere is different at the track than here at the garage, we expect the A/F numbers to vary slightly.
We detuned the car back to the original “stock” tune on the carb with the original metering rod and jets. The FAST Air/Fuel Meter once again confirmed that the car was out of tune. Our first dyno pull it showed an overly rich air/fuel ratio varying between 10.6:1 and 11.0:1 and produced 447 horsepower at the rear wheels on the Dynojet.
Next up was the “track tune” – and a 22 horsepower increase at the rear wheels resulting in a 468 and change rear wheel horsepower run. The FAST meter recorded the entire dyno run and produced an air/fuel ratio varying between 13.3 and 13.7:1. That is an aggressive ratio but if you watch it carefully in a street/strip application it falls into the high range of acceptable.
Using any of the available Air/Fuel ratio meters on the market can help you dial-in your street for better performance optimal tuning. It’s just a tool you can’t afford to be without.
What we like about the FAST meter is the fact that you can data-log your runs without a laptop, yet still use the FASTview PC software (a free download from FAST) which allows you to download, playback, store and even plot the data so you can compare air/fuel data logs on your personal computer. The playback also shows the precise elapsed time of the data log and displays the data not only as a raw number, but also with digital needle “gauges” that help you to spot air/fuel and rpm trends during your run.
That also being said, the FAST unit is easy to use and the guys at COMP Performance Group stand behind it. What more do you need to get started tuning your carb’d muscle car today?