5 Quick Tips To Tuning AEM’s Infinity Engine Management System

The power of today’s electronic engine management systems is unmatched, with flexibility and performance capabilities that were unheard of until recently. Today’s engine management systems rival the control systems produced by original equipment manufacturers, but also provide the adjustability and customization options needed for serious racing applications. It just so happens that one of these systems—the Infinity Engine Management System—is manufactured by one of our longtime sponsors, AEM Performance Electronics, and a recent online discussion I was watching spurred me to look into the capabilities of the system to satisfy my curiosity. I discovered that the Infinity’s capabilities give it the flexibility to be used in applications from drag racing to road racing, drifting, and beyond.

It also just so happens that one of the premier Infinity tuners in the world for drag racing applications—Eric Holliday of JPC Racing—is a personal friend of mine, so I reached out to him to dig deeper into the subject of engine tuning and why he prefers to use the Infinity system. Together we picked out five tips to tuning the Infinity, and why he prefers to use it over some of the other systems he sees regularly.

As defined, Volumetric Efficiency is “the ratio of the mass density of the air/fuel mixture drawn into the cylinder at atmospheric pressure (during the intake stroke) to the mass density of the same volume of air in the intake manifold.” Put simply, volumetric efficiency measures how full the engine’s cylinders are. A good OEM engine reaches volumetric efficiency of around 85 percent. In comparison, a highly modified engine can be 115 percent, and in the case of a turbocharged or supercharged engine can reach much higher figures—nearly 500 percent higher in the case of a Super Stock tractor pulling engine making 200 psi of boost. So you can see how using an engine management system that bases its calculations on VE can be a benefit to the tuner.

According to AEM’s Lawson Mollica, “A VE-based system like the Infinity will automatically determine how much fuel is required at any RPM under any condition. Once you set the VE table, you can forget about having to make fuel corrections. This will speed up your tuning time and lead to a host of other advantages.”

Use The Setup Wizard

In the interest of simplifying the setup process for a new user, AEM’s engineers have worked hard to make the system as flexible and easy-to-use as possible, and Holliday concurs. With many pre-programmed configurations already onboard the system, most of the setup is a point-and-click configuration, as long as the user knows the parts and pieces used in the build.

“The Setup Wizard does a really good job of laying out things in the fashion that you need them. When you go to set up your basic sensors—MAP, TPS, Coolant temperature—it has all of that stuff together. You click on the basic sensors, you tell it what pressure sensor you’re running and what pin it’s hooked to, and it’s done. It makes the setup for those extremely easy, Same with the crankshaft sensor. They make it simple to work with. Which injectors you have, how big the engine is, RPM limit, all of it. You just run through the wizard and set it all up,” says Holliday.

VE Table Tuning

Examples of modifications that affect volumetric efficiency include camshafts, cam timing, exhaust systems, intake systems, cylinder head configuration and flow, valve size, port design, and power-adder capabilities. Each of these modifications alone will change an engine’s volumetric efficiency. It’s easy to see that an engine management system that models itself around providing calibrations for these characteristics would be useful to the tuner.

“The Infinity is a VE-based system, so you’re mapping out the airflow of the motor, and then you put in the injector size, how much fuel pressure, and air/fuel ratio you want, and it does the calculation for you on how much fuel it needs to do that,” says Holliday.

“One of the things I like about the Infinity is that if I want to make a blanket change, like an air/fuel change… say it’s a boosted car, and we’ve been running it at 11.5:1 air/fuel, and I want to lean it up to 11.8:1, once the VE table is done, I don’t ever have to mess with that again. I can just go into the commanded air/fuel, set it to 11.8:1, and it globally changes everything. With a pounds-per-hour engine management system, you have to change both tables. So if you pull 10 percent air/fuel ratio away to lean it out, you also have to modify the fuel table minus ten percent so it will effectively make that change.”

As camshaft changes and other engine airflow changes that affect the VE table require a recalibration, Holliday has extensive experience with this portion of the Infinity’s adjustments through his work with NMRA Street Outlaw racer Tony Hobson’s supercharged Mustang, which is under constant refinement to find an edge over the competition.

“Let’s say I change the cam in it, and we don’t make a change to the VE table, then make a rip on the dyno. Now it’s pulling 5 percent down low and adding 5 percent up top, you know the engine is effectively making more airflow up top because it has to put more fuel in it,” says Holliday.

Utilize The New VE Table For Fueling Corrections

Today’s standalone engine management systems have correction logic that will make it possible to get onto the dyno with a base tuneup; between the wideband and the engine management system, it is possible to log the pull and determine where to make adjustments, and of what type.

The Infinity has a self-learning function, which will show the tuner how much correction is made from the original VE map using the system’s built-in InfinityTuner software. The Infinity also gives the user what’s called the New VE table that shows the suggested alteration to the VE map.

“Say you made a pass at the track that you’ve logged. It will show you that you commanded a VE of 50, for example, and it’s pulling X amount of fuel out. It shows you that the commanded should be 45 in this instance so that you can take that data to correct the fueling table as to what it should be,” says Holliday.

Built-in Protections Can Save You

One feature Holliday likes is the system’s built-in protection capabilities. These give the tuner the choice to set parameter limits—like low oil pressure or air/fuel ratio—that will shut the engine down.

“I think the protections are great, especially for guys who are just getting into doing their own tuning. There’s an air/fuel protection table that lets you set limits; how long it can be this lean, and it’ll cut spark or activate a rev limiter. For example, we use this in Mike Washington’s Mustang [all-motor Coyote record holder] and set the alarm to 13.2:1 air/fuel ratio. If he’s in high gear and it goes to 13.5, it’ll set a rev limiter at 4,500 rpm. Say his fuel pump died, and the pressure is dropping, which causes the engine to lean out to where the wideband oxygen sensor tied to the Infinity can’t correct any further because it is out of fuel pressure, we can set the table to shut it off. That tells the driver that there’s a problem, and he can get his foot out of it before we burn it up,” says Holliday.

There are two-dimensional protections for oil pressure, oil temperature, coolant temperature, air/fuel ratio, and overboost. Each of these can be tailored in the Infinity to limit the engine if the parameter is exceeded.

“It saved our asses on Tony’s car; we lost the belt to the oil pump when the bolts worked themselves loose on the pulley. It went onto the two-step and instantly laid over. Tony got his foot out of it right away, came back, put the oil pump belt on it, and we were good to go. Within half a second, it set a rev limiter at 4,500 rpm, so he knew something was wrong and was able to get out of it and shut it off right away,” says Holliday.

Since the Infinity works in conjunction with AEM’s CD-7 dash, Holliday credits the dash for also working to warn the driver when there’s an issue.

“That’s the beauty of the dash and Infinity working together. The whole dash starts flashing red—think The Fast & The Furious Danger to Manifold—which tells the driver ‘hey idiot, stop, there’s a problem.’” he laughs.

Multiple Boost Control Strategies For The Win

If you’re running a boosted engine—and let’s face it, it seems like more people have boost these days than the people who don’t—then the Infinity offers an immense level of configuration flexibility. While Holliday’s experience is in the drag racing world, we also learned that the Infinity’s strategies could be used for drifting, or time attack, rally racing, basically any racing endeavor where configurable boost control is useful.

“The boost controller has two different tables that it looks at—I can do boost over time with a transbrake release, and from there, I can have a secondary table based on intake air temperature values. Let’s say the IAT goes sky-high, I can have a secondary table that will reduce boost by X percent if the conditions are met between the two tables,” says Holliday.

“I can also do by time and gear. Let’s say in first gear I want to leave on 8 pounds of boost and ramp up to 15 over this amount of time, then in second gear, I want to instantly go to 20 and ramp to 26, then in third gear full boost for everything. This would work especially well in a stick-shift turbo car. The tuneup still has to be somewhat in line with the traction control as it’s not a miracle worker. The traction control is there to catch it if you get a little too aggressive.”

The control per gear is especially useful in traction-limited situations like a “street”-prepped racecar, time attack, or rally racer might experience.

In Conclusion

It’s clear that AEM’s engineers have considered basic and advanced tuning needs with the infinity system; the documentation for the system is extensive and well-written. The flexibility of the InfinityTuner software gives the end-user access to the necessary parameters for engine control—no matter the motorsports discipline—and the features of the system make it one of the top choices to control today’s late-model high-performance engines on the track, whether it’s curved, straight, or otherwise.

I hope you gained greater insight into the Infinity’s capabilities thanks to Eric’s expertise and willingness to share his knowledge. I know I sure did.

(Eric Holliday photo credit: NMRA)