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1979 Dodge Demon - The EBay 5.7 Hemi Engine

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Factory Harness And SCT Or Diablosport Tune

Once you've sorted the factory computer and harness, you can access it with an aftermarket, handheld programmer. We spoke to Chris Jensen at DC Performance in west Los Angeles for the options. He says that for the '04 to '06 Hemi controllers, the SCT tuner can be used to upload basic cold-air tuning maps. All you need to do is call the company and explain what you want, and SCT will email you the program to upload onto the system. If you want to tune the car yourself, you'll need the Pro Racer software and some kind of data logger for dyno runs or some time on a chassis dyno.

For the '07-and-newer Hemi, you'll need the DiabloSport tuner that works in the same way as the SCT, by downloading programs that are included with the tuner or ordering a custom tune based on your needs.

"The '07-and-newer Hemi controllers can be more difficult to work with, and disabling the antitheft security can be much more of an issue than with the '05 to '06 Hemi controllers. Even if you have a '07-and-newer engine, it is advisable to use an earlier NGC3 controller from '05 to '06. You can also minimize problems by ordering a factory-fresh controller, since the controller will not have been ‘married' to a vehicle," Jensen says.

We're not kidding ourselves—we'd likely need to order the tuner and the Pro software and pay a dyno guy to dial in the car. We also learned that these tuners require the drive-by-wire pedal mentioned above, which we did not get with our used engine. According to Jensen, the drive-by-wire system works with the computer to calculate the power output needed rather than just sending a WOT signal, so a factory pedal and the pedal position switch is needed.

How Much?
Description PN Price
SCT tuner 9550 $379.00
Pro Race software N/A 349.00
S&P Dodge truck pedal N/A 139.95
S&P pedal-position switch N/A 259.95
Dyno day N/A 1,000
Total $2,127.90
Optional DiabloSport tuner U7137 309.00


We've heard the MegaSquirt is the most interactive way to fire up a fuel-injected engine. It's low buck for sure, coming in at $675.94 for the solder-it-yourself MS330 MegaSquirt III and a basic wiring harness. According to Matt Cramer at DIY Auto Tune, for that price you get goodies like sequential fuel injection with individual injector timing and pulse-width control, a data logger, progressive nitrous control, boost capabilities, and extra outputs for electric fans and fuel pumps. The MS330 controls the ignition timing but is designed to work through a control module that amplifies the spark. The company recommends a pair of four-cylinder Bosch control boxes that cost about $180 each.

The throttle pedal issue is partly solved. You can use any cable-operated throttle-body that has a throttle position sensor, including less expensive GM LS parts, if you can build an adapter and plug it in the system. At press time, BBK told us of a Hemi cable-operated throttle-body it was developing, but it did not yet have a price or part number.

To take advantage of the data logger, Cramer recommended a wide-band O2, like the Innovate LM1, which adds another $249-plus a day at the dyno to get it dialed in.

How Much?
Description Source PN Price
MS330 DIY Auto Tune MS330-K $675.04
Bosch control box (2) DIY Auto Tune 0227100211 180.00 (each)
Cable-operated throttle-body BBK N/A Call
Dyno day Westech Performance N/A 1,000.00
Total without throttle-body $2,035.04
Optional wide-band O2 meter Innovate Motorsports LM-1 249.00

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