Honda Challenge 2 National Champion Jeremy Croiset (No. 25) added an AEM four-channel wideband controller to his car, which wouldn’t guarantee a win, but it did ensure he was getting all the power he could from his car’s B16 engine.

The effort you put into your racing is often described in tenths. Six-tenths is a cool-down lap. Seven-tenths is as hard as you push with a passenger on board, and ten-tenths is when you push yourself and the car to the limit. Reaching for those last few kernels of speed can mean the difference first and second place. The difference is often negligible, but its effect is undeniable.

There’s also a way to tune your engine to ten tenths.

Tuning your air-fuel ratio with a wideband controller has long been a good way to tune a car and extract more power — and a lot of NASA racers do it. But there is a method for taking that tuning a step further. By tuning each individual cylinder through a four-channel wideband controller, you can extract those last few units of horsepower and those last few pound-feet of torque.

AEM Performance Electronics makes a four-channel wideband controller that allows for precise tuning of each cylinder, and it does it at a price point that is accessible to the amateur racer. Until AEM initially introduced single- and dual-channel controllers, the only wideband tuning equipment available was prohibitively expensive.

“You need a wideband air/fuel controller to tune,” said Lawson Mollica, director of marketing and PR for AEM. “When we were getting ready to launch the first version of our engine management in 2002, wideband air/fuel controllers were typically attached to dynos and were pretty expensive. Not a lot of guys had access to put one into a car, so our engineers developed a wideband controller that was affordable and portable. This way, a racecar could travel with a wideband and use it for track tuning at an event, when you need to tune on the fly. We developed single- and dual-channel controllers that mounted in the exhaust collectors.

Each primary tube gets fitted with a bung for a wideband oxygen sensor.
Each primary tube gets fitted with a bung for a wideband oxygen sensor.

“In 2003, our engineers came up with the idea of putting a controller into a gauge for immediate reference to AFR. It was a great idea then, as evidenced by the fact that there are several companies now who have designed their own version. But with more than a decade of experience developing wideband technology, I believe ours delivers the best accuracy and value.”

Why bother tuning each cylinder? Isn’t tuning with a single wideband sensor at the collector good enough? Generally speaking, yes, but tuning each cylinder is the equivalent of pushing your driving to ten-tenths. Here’s why. Be it manufacturing variances, intake manifold design, exhaust manifold design, injector flow variation or even something as simple as a misaligned intake gasket, air/fuel ratios vary from cylinder to cylinder. Tuning each cylinder also is better for the engine.

“The other side of that is you’re going to run a lot safer because each cylinder is running at an ideal AFR,” Mollica explained. “It’s incredibly affordable for what it is, and for the potential for tuning that it provides. When you add in the safety factor, that you’re ensuring your engine is running at optimum AFR. That promotes efficiency, which of course promotes power and also engine longevity. And when you think about it that way, it becomes pretty darn affordable.”

Retail price for the controller and one sensor is $630 for controller, plus $60 for each additional sensor.

To adjust the air/fuel ratios, you’re also going to need a stand-alone computer, which, conveniently, AEM also manufactures. However, the four-channel controller is not exclusive to AEM stand-alone management systems. You can use it on lots of different stand-alones from competing manufacturers, and they are listed on AEM’s website. You might have to check with the manufacturer of your computer, but if they don’t have AEM’s CAN protocol, AEM will make it available to them, and AEM’s four-channel wideband controller includes 0-5v outputs that you can pin into an engine management computer for feedback.

The AEM controller comes with one sensor. Each additional sensor is $60.
The AEM controller comes with one sensor. Each additional sensor is $60.
The sensors screw into the bungs like OEM equipment. AEM’s stainless-steel, finned stand-off bungs promote sensor cooling and reduce restriction over standard bungs.
The sensors screw into the bungs like OEM equipment. AEM’s stainless-steel, finned stand-off bungs promote sensor cooling and reduce restriction over standard bungs.

NASA Director of Sponsorship and Marketing Jeremy Croiset installed a four-channel system on his National Championship-winning Honda Challenge 2 car. Installation time was one afternoon, Croiset said.

“In all honesty, this system is super easy to install,” Croiset said. “It looks complicated, but all of those wire ends are labeled and they plug right into the sensors. Red and black for power and ground, four white wires for sensor input, one extra ground and that’s it.”

Wiring the kit is pretty straightforward. Red and black wires are for power and ground. The four white wires are for the sensors, and there is one extra ground wire.
Wiring the kit is pretty straightforward. Red and black wires are for power and ground. The four white wires are for the sensors, and there is one extra ground wire.

Croiset and Mollica said gains of 3 to 5 percent across the rpm range and flatter torque curves are possible.

“It’s not massive, but if you’re in a competitive environment, you’re going to say which power curve do I want?” Croiset said. “If you switch to a cylinder-tuning system, you’re going to get some gains, but you’re going to know if your car is making reliable power because you’re not running any cylinders lean.”

In many cases, a four-channel wideband controller doesn’t cost you anything according to the rulebook or in points if you are in Performance Touring classes. What’s more, you know your competitors are likely to pony up for this kind of system.

“I love racers, because they are always looking for that competitive advantage,” Mollica said, laughing. “It’s like ‘Where can I find some extra horsepower? Just a few more to pull me out of that turn quicker and down the straight faster.’

“It’s an incredibly affordable product to extend the longevity of an engine and ensure your engine is performing at its best,” he added. “If you think about the down time and the parts costs you could save on having to rebuild your engine using a four-channel wideband, that alone would pay for itself in a season.”

With snap-lock connectors for each lead, the AEM harnesses are weather resistant.
With snap-lock connectors for each lead, the AEM harnesses are weather resistant.
The controller is small, light and easy to mount, even under a crowded dashboard.
The controller is small, light and easy to mount, even under a crowded dashboard.
With input from the sensors on each primary tube, you can change the fuel maps through the stand-alone engine control module.
With input from the sensors on each primary tube, you can change the fuel maps through the stand-alone engine control module.
Dyno testing before and after will reveal modest gains, but the four-channel system extracts the last few kernels of power you can get from your engine.
Dyno testing before and after will reveal modest gains, but the four-channel system extracts the last few kernels of power you can get from your engine.
Adding the AEM four-channel controller to an S2000 with a stock engine and bolt-on turbocharger produced 13 more horsepower and one pound-feet of torque while keeping air/fuel ratio consistent across all cylinders. For turbo applications, AEM makes an exhaust backpressure compensation kit, which allows you to mount the sensors ahead of the turbo.
Adding the AEM four-channel controller to an S2000 with a stock engine and bolt-on turbocharger produced 13 more horsepower and one pound-feet of torque while keeping air/fuel ratio consistent across all cylinders. For turbo applications, AEM makes an exhaust backpressure compensation kit, which allows you to mount the sensors ahead of the turbo.
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Images courtesy of Jeremy Croiset, AEM Photo and Bisimoto Engineering