Chevy Engine Tuning - Tuning The Untunable

Through The Power Of Computer Tuning, Project X Picks Up Extra Horsepower

Dan Ryder Oct 18, 2007 0 Comment(s)
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With the ever-increasing popularity of stuffing late-model powertrain components between early model framerails, things can become tricky. Either you love the idea or are totally against it. Many are just afraid of the fact that their toy will contain fuel injection run by an Electronic Control Module (ECM). Others believe that if it didn't come from the factory that way then it shouldn't be. "Long live the carburetor," some exclaim, but with a little research you'll find that a jet change and timing advance can be performed via a few keystrokes, while keeping a clean set of hands.

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Here's the GM Performance Parts Ram Jet 502 neatly nestled into the confines of Project X.

Bring in Project X, the world's most famous magazine project car, appearing in both Popular Hot Rodding (beginning in 1965!) and Super Chevy. This bright-yellow 1957 Chevy has been around long before I was a twinkle in my father's eye. This car is somewhat of a celebrity in its own right. It is the longest running, most popular project vehicle in publishing history. It has been to dragstrips across the country, including ones that no longer exist. To add to its credits, Project X had a role in the 1980 movie "Hollywood Knights," starring Michelle Pfeiffer, Tony Danza, and Robert Wuhl. Earlier this year at the Super Chevy Show in Fontana, X was introduced and the fans went wild. Readers have certain affection for the car and will continue to, we're sure.

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Due to the durability and compact size (4x4 inches) of the MEFI controller it can be mounted almost anywhere. The mounting point of choice was below the upper intake plenum, as seen here.

Project X has gone through its fair share of changes, serving the readers with much feedback throughout the years. Many engines have also resided within the framerails of this beast, the latest being a GM Performance Parts Ram Jet 502. As advertised, this engine pumps out a stump-pulling 502 hp and 565 lb-ft of torque. Backing the 502 is a 4L80E transmission, which cannot only handle the power, but also contains overdrive-nice for long trips. Engine management for the injected GM crate engine comes from the GM Performance Parts MEFI controller.

"What the heck is a MEFI?" you ask. MEFI stands for Marine Electronic Fuel Injection. It's an engine controller manufactured by Delphi Electronics. It is compact, rugged, waterproof and can be mounted virtually anywhere. The stand-alone controller is ideal for marine, off-road, street machine and racing applications. The MEFI has been race proven over and over by top racers involved in the Dakar Rally, Baja 1000, offshore boat racing, and the salty surfaces of Bonneville.

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Located on the right side of the upper plenum is the GM-style MAP sensor. MAP stands for "manifold absolute pressure." This particular MAP contains a vacuum nipple, which goes into the plenum, sealed by an O-ring. Internally, the MAP sensor contains a vacuum sensitive potentiometer, thus sending a signal based off of a five-volt reference to the MEFI controller. At idle, vacuum is high; under load, vacuum decreases. Based off of the readings of the MAP sensor, throttle position sensor, and oxygen sensor, the computer can calculate and correct necessary variable outputs for the timing and fuel injector pulse.

When purchasing the Ram Jet 502, it comes with a MEFI engine controller and wiring harness, programmed and ready to roll. Its biggest downfall is that until recently the programmer had a base tune that couldn't be changed by the end user. While this is great for simplicity, have you ever seen a factory tune that couldn't be tweaked for more performance?

Our latest saga with the '57 began when we were getting it ready for the first-ever Fontana Super Chevy event and the engine wouldn't fire. We had a no-start problem that was traced to the controller. Instead of replacing the unit with another non-programmable unit, we decided (being the greedy bunch of motorheads that we are) to call upon Arizona Speed and Marine to give us some insight on how to remedy the issue and gain some additional ponies.

Jim Shofner (owner of AS&M) brought the MEFI 4B engine controller to our attention. It is completely tunable and user friendly. The MEFI 4B can be used on various engines, such as the Gen-3 and Gen-4 LS engines, GMPP's Ram Jet 350 and 502 crate powerplants, and the Ecotec 4-cylinder. Optional equipment for the MEFI 4B includes a Wide Band Close Loop Oxygen Sensor (single or dual), Racepak Digital Dashboard, and Racepak Smart Gauges. All items listed will aid in gathering sensor parameters for easy tuning.

Another neat feature is the existence of auxiliary outputs, which can control the coolant fan, along with nitrous oxide activation. With the AS&M InGenius software and controller in hand, we headed off to Westech for the installation, and some intense dyno tuning.

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