When it comes to late-model fuel-injected performance, and engine swaps in particular, the Chrysler Hemi camp has always come up short—and it's not for a lack of trying on the part of enthusiasts or even aftermarket manufacturers. The big issue has always been with Ma Mopar. It seems the good Lord—uh, we mean Chrysler—giveth and taketh away with the same hand.
Chrysler's chronic problem with a lack of adoption by the performance community is really a two-fold issue. First, the factory encryption of the Gen III Hemi ECU is so well obfuscated that even the largest aftermarket companies with the most talented pool of code crackers cannot gain entrance to its programming—not that Chrysler ECUs are anything special to start with. And when the aftermarket finally does manage to break in, the factory has often moved one or even two more ECU generations down the road. What's more, throttle-by-wire operation complicates things further. Second, Chrysler engages in the schizophrenic practice of changing ECU manufacturers and harness designs with not only dizzying frequency, but with startling unpredictability. If you swap a late-model engine, harness, and/or ECU from a wrecked vehicle into a hot rod, you not only need to know the make, model, and year of the vehicles they originated from, but you need to know the exact date each vehicle was manufactured—that's because it's not an uncommon practice for Chrysler to switch ECU, sensor, injector, or harness manufacturers mid-year.
What should've been a simple idea in theory—swapping a late-model Hemi into a classic Mopar—is finally simple in the real world, thanks to Holley's new line of Gen III Hemi Plug-And-Play harnesses.
All this conspires to throw a thick, damp blanket over a rather inspired feat of Chrysler powertrain engineering. Through the Gen III Hemi's 12-year evolution, Holley Performance has been studying the powerful Pentastar plant, and armed with their capable arsenal of Dominator and HP ECUs, now has harness, sensor, injector, TBW, and ECU coverage for Chrysler's confusing array of Hemi iterations. The idea behind Holley's new Hemi program: just tell them what version of Gen III Hemi you have, and they'll send you the right harnesses and ECU to get it running in a hurry.
The Holley Plug-And-Play Gen III Hemi program covers virtually every version of the 5.7-liter Hemi going back to 2003 (including newer "Eagle" variants), all 6.1-liter SRT powertrains, 2011-up 6.4-liter "Apache" Hemis, and all Mopar Performance Gen III 426 crate engines. And depending on the mods you plan and the extensiveness of the programming you intend to do, all Holley Plug-And-Play Hemi harnesses can be used with either a Holley HP or a Holley Dominator ECU. (Throttle-by-wire is also supported in the latter.) The main take-away from Holley Gen III Hemi Plug-and-Play program is that irrespective of your donor Hemi or the classic Mopar you plan to swap it into, Holley is now building and stocking every component you'll need to get the job handled, whether that's a main harness (both early and late crank/cam sensors are supported), an injector harness (USCAR and Bosch Jetronic injectors are covered), a coil harness (early FCI and late Tyco are available), a drive-by-wire harness (early Tyco or late Molex), any of the constellation of injector sizes, Hemi-specific sensors, throttle bodies, and of course your choice of HP or Dominator ECUs.
Holley's HP ECU: compatible with Holley's new Hemi Plug-And-Play harness line and includes many premium features like self-learning, data logging, traction control, boost control, water/meth injection, nitrous control, knock sensing, MAP sensor capability, full control of fuel and spark (including coil-on-plug) and lots more.
Holley's move to support the Gen III Hemi with such an extensive product line means that the Gen III Hemi tribe has essentially caught up technologically to the well-established factory-supported LS market—which by no accident Holley has been deeply involved with over the last six years. That experience has informed Holley on ways to accelerate and streamline its Hemi program, cutting years out of the product development cycle, and all for the gain of Gen III Hemi fans everywhere. Along those lines—and it's just speculation on our part—we wouldn't be surprised to see Holley roll out a complete line of supporting swap products like motor mounts, accessory drives, complete exhaust systems, bellhousings, and oil pans (they already make headers through their Hooker connection), all in the same vein as Holley's extensive and widely popular line of LS swap items. In fact, with the Holley LS Fest such a success, we can easily imagine a Holley Hemi Fest. It even rolls off the tongue nicely!
Holley's flagship Dominator ECU also works with the Gen III Hemi Plug-And-Play system and adds even more premium features like support for drive-by-wire. The antithesis of the factory Chrysler ECU, Holley's Dominator allows you to do anything you can think of, including supporting a very sophisticated race set-up.
