Howell Engine Development Inc. has recently developed and released a new wiring harness designed specifically for General Motors 2014+ LT1 engines being swapped into vehicles. Howell EFI has been in the EFI harness market since 1988; the company was founded by the father Bill Howell and son Matt to meet the demands of enthusiasts converting to EFI on their vehicles. Howell EFI specializes in adapting late model GM EFI equipped engines into older “pre-computer” vehicles effortlessly.

The LT1 wiring harness kits being produced by Howell EFI are designed to be swapped into specific vehicles, and the list of potential vehicles continues to grow.  The LT1 swap specific harnesses currently available are, but are not limited to; the 1992-1997 Corvette (PN #H223) and for the 1993-1997 Camaro/Firebird (PN #HF47). The wiring harness gives the end user the ability to utilize the OE direct injection and VVT. Also, all Howell GM EFI harnesses have the ability utilize GM’s OE diagnostic commands.

Durability in Mind

The wiring harness are made with durability in mind, and Howell Industries says all its harnesses incorporate nylon sheaths to protect the wiring from the elements and the heat generated in the engine compartment. All of Howell EFI harnesses are constructed using GM Packard high-temperature insulation (TXL Insulation), with genuine Packard connectors and end terminals. Howell claims their harnesses will function reliably for 100,000-plus miles.

Howell EFI LT1 swap wiring harness for the 1994-1997 Camaro/Firebird (PN #HF47T)

Matt Howell, co-owner of Howell EFI, said that the harnesses were designed to ease installation and the whole kit is “terminated…basically using a one ground system”. All the necessary relays for the swap are included, along with a dedicated fuse block, and an OE GM OBDII port for diagnostics. The design allows the closed and open loop ECM functions to operate properly. Also the GM on-board diagnostics will properly display any engine malfunctions by illuminating the check engine light (CEL).

Howell went on to say “We tried to make this straightforward as we can, the customer only has 3 points of power to connect; the fuel pump, ignition, and battery.” This makes the kit less troublesome than some other harness options, from different manufacturers. “This is a true plug and play system,” according to Howell, no modification is necessary for installation. The wiring loom is cut-to-length, ultimately forming a nice tucked wiring harness as the end result.

Lt1 Misc. Conversion Components

Howell EFI 1994-97 ECM for LT1 swapped Camaro with 4L60E Trans. Reprogrammed for No-VATS, and to match engine, axle ratio and tire size. (PN #HF47TE)

Howell has also introduced a transmission ECM (PN #HF47TE) for the 4L60E to be used in conjunction with the LT1 engine. The ECM is reprogrammed to run No-VATS (vehicle anti-theft system), match engine size, axle ratio and tire size. Also available for LT1, LS, or Vortec swaps are pre-wired high pressure fuel pumps (PN #FP206) to meet the needs of various flow capacities. Howell even offers parts to convert, and run, the originally equipped GM speed density (PN #HK9293), MAF sensors (PN #MA9495), and even GM knock sensors (PN #HK45).

As LT1 engines slowly trickle into the junkyards and auto-recyclers around the country, and LT1 crate engines become more prevalent, there will be a greater need for parts to complete these swaps. Having a harness specific to that swap can make things even easier.

We anticipate that 2016 will bring with it a slew of more LT1 swaps, and with it the need for more parts like this.