Ultimate Mopar Swap

In­stalling a 700hp Hell­cat crate en­gine in a ’17 Ram Rebel


Ever since Mopar re­leased its Hell­cat V-8 as a crate en­gine last year, Ram en­thu­si­asts have con­sid­ered the pos­si­bil­ity of an­other su­pertruck that could re­vive the per­for­mance pas­sions the iconic SRT-10 mod­els pro­duced from 2004 to 2006. If you re­mem­ber, those reg­u­lar-cab mod­els came with a 500hp, 8.3L, all-alu­minum

Viper V-10 en­gine and six-speed man­ual trans­mis­sion. Ram also re­leased a Quad Cab ver­sion with an au­to­matic trans­mis­sion. Both mod­els were street brutes with more than 500 lb-ft of torque available through much of the power band. How­ever, with a Hell­cat un­der the hood, more than 500 lb-ft of torque would be available at the rear wheels—not just the fly­wheel!

Rated at 707 hp and 650 lb-ft peak torque, the 6.2L su­per­charged Hell­cat en­gine has all the tools to cre­ate an­other uber-per­for­mance street truck, if you know how to drop one in a late-model plat­form. Dakota Cus­toms, lo­cated near Rapid City, South Dakota, spe­cial­izes in Hemi con­ver­sions and has swapped nu­mer­ous Hell­cat en­gines into Jeeps. But this was the shop’s first Ram project, which pre­sented its own set of chal­lenges.

“Get­ting the en­gine to run wasn’t a big prob­lem, but there were spe­cific cal­i­bra­tions that had to be ad­dressed,” shop man­ager Dan McKeag says. “For ex­am­ple, the torque man­age­ment pro­gram for the trans­mis­sion shifts. There are cool­ing fan dif­fer­ences, ABS brake dif­fer­ences, and more.”

Phys­i­cally, there were few is­sues when it came to re­plac­ing the stock 5.7L Hemi with the Hell­cat. The team re­tained the stock eight-speed au­to­matic trans­mis­sion, flex­plate, and torque con­verter. This swap was per­formed on a four-wheel-drive truck, al­though it would be just as un­com­pli­cated with a rear-wheeldrive model. Grind­ing was needed to clear the al­ter­na­tor, and a lit­tle surgery was re­quired on the firewall to make room for the in­ter­cooler fluid lines.

The key to mat­ing the Hell­cat with the Ram is the wir­ing har­ness. Dakota Cus­toms used a Hell­cat PCM and fused the stock wir­ing har­ness with a Hell­cat au­to­matic har­ness. The team ba­si­cally laid out the two har­nesses, noted the dif­fer­ences, and con­sulted wir­ing di­a­grams to make sure the cor­rect pin connectors were uti­lized.

Once the Hell­cat en­gine was swapped in place, the PCM could be un­locked and re­cal­i­brated with the nec­es­sary in­for­ma­tion that keeps both the truck and the en­gine happy. For ex­am­ple, the Hell­cat re­quires a multi-phase fuel pump to keep up with the su­per­charger de­mands. Dakota Cus­toms couldn’t use the stock Ram pump, so the crew swapped in an Aero­mo­tive dual fuel pump and reg­u­la­tor. Also, the Ram comes with an en­gine-driven fan, but Dakota Cus­toms wanted an elec­tric fan to ad­dress cool­ing is­sues. The crew found one from an older Ram V-6 pickup and cal­i­brated the PCM to operate it ac­cord­ingly.

The swap al­most dou­bled the horse­power and torque pro­duced by the fac­tory 5.7L Hemi. In ad­di­tion to the per­for­mance up­grade, Dakota Cus­toms added bold SRT Hell­cat graph­ics and a more ag­gres­sive wheel-and-tire combo, with 35-inch Toyo tires wrapped around 22-inch SRT replica wheels. With these looks and power, there was only one more thing to do—think of a name. The Ram Cat? The Hell Ram? The Rebel Hell? The pos­si­bil­i­ties are end­less.

A 707hp Hell­cat V-8 en­gine stands ready to be swapped into a new Ram pickup.

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