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Jeep V8 Engine Swap Options

Posted in How To: Transmission Drivetrain on July 1, 2011
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Photographers: The Manufacturers

Last month I ran down a bunch of junkyard and budget engine swap options I con- sidered for my ’89 Wrangler. After failing to find any decent low-mileage swap candidates in my area, I expanded my search to include late-model salvage yard and brand-new crate engines. You’ll notice Chrysler engines are barely touched upon and the Ford offerings are completely ignored. There’s a reason.

For starters, most late-model Ford V-8 engines like the 4.6L and 5.4L are bulky, wide, and not well supported by the aftermarket in terms of swapping. As for the Chrysler engines, I’d really only consider a 5.7L Hemi. My seat time in 6.1L-powered vehicles has proven disappointing in real-world driving scenarios. The 6.1L Hemi is a very peaky engine that’s not great for slow-speed off-road use. The low-end is lacking and when the power finally does come in around the mid-3,000 rpm-range, it hits like a sledge-hammer. It’s almost like driving a two-stroke V-8. And while the 5.7L Hemi is more real-world, there are limitations and drawbacks that preclude swapping into older chassis, including relatively soft aftermarket support, high cost, limited engine-to-transmission adapters, and (sadly) a lack of factory-backed enthusiast support. Crate engines from Mopar Performance have been small in quantity and ridiculously expensive. Rather than offer production-based options like GM Performance, the Mopar stuff is comparatively high-zoot and spendy.

So, it’s little wonder I began worming my way into LS-land, researching late-model GM powerplants. The nice thing about the Gen III GM engine options is they’ve been around in one form or another since ’97. Parts interchangeability between the different Gen III engines is strong, as is the aftermarket support in terms of conversion harnesses, accessories, exhaust, and other components. They’re durable, make great power, and respond well to aftermarket modifications. Furthermore, you can easily mate them to a host of transmissions (including factory Jeep offerings), and they’re cheap and plentiful if you’re looking to score used take-outs.

So which is it gonna be for my Project Why-J? Normally I’d tell you to tune in next issue to find out, but as of this writing I’m in a holding pattern for my engine-of-choice. You see, I’m in line for one of the first-ever GM Performance Parts E-Rod 5.3L packages. GM already has its E-Rod LS3 available, but there are a number of factors that make me want to wait for the E-Rod 5.3L, which I’ll happily share with you in Part 3 of this series—as soon as my new engine shows up.

Wrecking Yard Gen III Prices
If you’re bargain hunting, forget the more-exotic all-aluminum LS engines and go straight for the ’99-up pickup and SUV engines. While a used aluminum LS1 or LS2 may fetch $2,000 from a wrecking yard, you can score an iron-block 6.0L LY6 or LQ4 for $1,000-$1,500. Still seem steep? Then forget the big-bore 6.0L and go straight for the meat-and-potatoes 5.3L. GM put millions of ’em in pickups and SUVs since 1999. The lower-mileage (sub-100,000) iron-block LM7 5.3L with PCM and harness can be found for around $500 and it’s not uncommon to find higher-mileage (150,000 or more) engines for $250. Or, if you’re sketched-out thinking of buying an engine over eBay, Pacific Fabrication sells quality take-out engines complete with an easy-to-install harness, all the accessories, and more. Either way you go, don’t let the miles scare you. GM builds one hell of a durable engine.

5.7L Hemi
I’ve owned a 5.7L Hemi-powered vehicle for seven years and it’s been flawless for 120,000 miles. But that doesn’t make the engine cheap or easy to swap in an older vehicle. And you can’t mate it to your current tranny (unless you’ve already got a Chrysler V-8). However, if you’re dealing with a TJ or JK it’s a different story. Companies like AEV, Burnsville Off Road, Hotwire Auto, and TeraFlex all make conversion components and harnesses that let you plug a Hemi in your modern Jeep and go. Another great source for crate engines, front accessories, and fueling systems for Hemi engines is Bouchillon Performance. However, in most cases you’re stuck running the big five-speed 5R45 auto transmission or the Ram truck’s somewhat-rare six-speed manual. Furthermore, when compared with a similarly sized GM Gen III-series engine, the Hemi just doesn’t deliver the same gooey performance down low. It’s a great engine, but I think the GM Gen III-series gives you better drivability and power and is better suited for swapping into an older Jeep.

Front Accessories
You can buy aftermarket front-accessory packages from a variety of manufacturers, but in almost every case they’re insanely expensive. Another reason to gravitate towards GM Performance is its front accessory packages created from production parts. Offered for Corvette, CTS-V, LSA, LS9, and now the LC9 (truck-type front accessory package), the engine swapper can select a package that offers a layout that fits his chassis. Most Jeep and 4x4 enthusiasts will go with the LC9 (truck/SUV-style) or Corvette package. For just over $800 it includes all the accessories (A/C compressor, alternator, power steering pump) idler pulleys, brackets, belts, and bolts. Or, there are less-expensive kits without the A/C components. The A/C compressor can cause frame interference when installed in a Wrangler, but Novak Conversions offers an A/C compressor relocation kit under PN ACG3 that mounts a Delco R4 compressor in front of the passenger-side cylinder head. The kit only works with the truck-type front accessory and water pump.

If you want new, go straight to the source. GM Performance Parts uses its production-based parts and assembly infrastructure to offer (comparatively) inexpensive crate engine options ranging from its $3,000-ish 327hp 5.3L HO to hot fuel-injected or carbureted LS3, to LS7, supercharged 556hp LSA, or the madman LS9 with dry-sump oiling system and supercharged 638hp—all come with a 24-month, 50,000-mile warranty. GMPP also offers transmissions and other drivetrain components, wiring harnesses, ECU, front accessory packages, and lots of other stuff you’ll need to wire or fire your new engine.

Smog-Legal Crate
Introduced at the 2009 SEMA show, GM Performance created a buzz with its E-Rod LS3 engine package, which included a production-spec 430hp LS3 Corvette engine, wiring harness, exhaust manifolds, catalytic converters, O2 sensors and bosses, fuel tank evaporative emissions canister, MAF sensor and boss, accelerator pedal, air filter, and ECU. The result was a crate engine package with 50-state CARB certification for use in ’95-older OBDI vehicles. In 2010, GMPP announced plans to expand the E-Rod program to include a 315hp 5.3L, 505hp LS7, and 556hp supercharged LSA and is currently working towards expanding the CARB E.O. coverage for OBDII and new specialty construction vehicles.

Aftermarket Crate Options
Shown in the photo is the 6.0L LY6HO crate engine from MAST Motorsports. MAST is the Dynatrac of Gen III crate engines, going the extra mile in its design and calibration phases to ensure both streetability and survivability in its engines. Designed to safely run on 87-92 octane fuel, the 480hp 6.0L crate engine is one of MAST’s more-mundane offerings. The company does crazy-horsepower complete stroker engines, high-flow cylinder heads, VVT camshafts, electronics packages, fueling systems, and lots more.

Or, if you don’t want to think too hard, Turn Key Engine Supply offers a line of GM Performance-based or custom in-house-built crate engines with simple wiring hookups and front accessory packages already installed. The fuel pump, filter, and even engine oil are included. Just slam it in your chassis, wire, and fire it and you’re down the road.

Novak Conversions uses genuine GM computers and harnesses with a dirt-simple five-wire hookup. The company focuses more on stock-type reliability and drivability than all-out horsepower with its 4.8L, 5.3L, 5.7L, or 6.0L packages. As an added bonus, Novak can supply you with all the conversion components if you needed.

Or, in addition to providing quality take-out engines, Pacific Fabrication also offers new GM or custom-built crate engines at any level of completeness, from bare long-block to ready to drop in, wire, and fire packages.

Not enough? Try Google—there are dozens of places offering GEN III crate engines from Lingenfelter Performance to Street and Performance.

ECU Cautions
There are dozens of aftermarket and factory harnesses available for production GM or aftermarket ECU systems. Keep in mind, before you select your engine management system you’ll need to know which engine you’re using. The’97-’06 models utilized a 24X crankshaft reluctor (mounted on the front of the crankshaft behind the timing cover) to send the appropriate signal to the ECU, while the ’06-present engines use a 58X reluctor. The crossover happened in 2006 with some overlap depending on vehicle chassis and date of manufacture. As Mike Noonan of EFI Connection explains, federal regulations required the finer resolution to determine misfire and improve emissions. You can technically use a 24X computer to run a 58X engine, but you’ll need to use a PN L460065397 conversion module from Lingenfelter Performance. However, you can’t reflash a 58X computer to work on a 24X engine. Also, you can’t run a cable-operated throttle body on a 58X engine unless you’re running an ECU with aftermarket software or convert to the 24X computer. Point is, if you’re buying an aftermarket harness and ECU to control your junkyard take-out or new crate engine, make sure to choose the appropriate hardware and software package.

GM Gen III Engine
Years Manufactured: 1997-present
Found In: GM introduced the 5.7L LS1 in the ’97 C5 Corvettes and then into the ’98 Camaro and Firebird platforms. From there the LS-series evolved into the LS2, LS3, LS7, and so on. The ’99 model year GM pickups and SUVs got either the 4.8L LY2, 5.3L LM7, or 6.0L LY6, with different versions as the years progressed.

Pros: Very durable engines that offer great low- and mid-range power in most cases. Most gasket surfaces feature O-rings for improved sealing. High support from aftermarket in terms of installation components and transmission adapters.

Mounting: Both Novak and Advance Adapters offer several different methods for mounting these engines in a variety of Jeep vehicles. Systems for direct-fit or universal mounting are available. Furthermore, conversion motor mounts to place a Gen III in place of an older small-block Chevy engine are available for a bolt-in solution if you’re already running a Gen 0, Gen I, or Gen II Chevy engine.

Mating: Compared with a standard old-school Chevy bellhousing, the Gen III engines have one extra bolt hole at the 12 o’clock position, but you don’t need to use it. As such, you can bolt any Chevy transmission or bellhousing from ’55-up to a Gen III engine. That means virtually any adapter for a small-block Chevy can work to mate a Gen III engine to your drivetrain. You will have to use a special Gen III flywheel or flex plate specific to your engine, but there are so many factory and aftermarket solutions that this isn’t a concern.

Cooling: The upper radiator hose on most Gen III vehicles is on the driver-side and the lower is on the passenger. There are tons of aftermarket conversion radiators out there. You can run an electric fan or a factory truck-type mechanical fan. If you choose a mechanical fan you’ll need to use the truck water pump, as the car water pumps don’t have the provision on the pulley to accept the mechanical fan and clutch. Also, the truck water pump upper hose inlet is angled differently than the car type. The car type sticks straight out towards the radiator, while the truck type angles it sort of up and towards the passenger-side headlight.

Fueling: The Gen III engines require a minimum of 50 psi to start. Ideally they’re happiest with 58-60psi. The factory returnless OBDII pumps on most ’96-up Jeeps are internally regulated and won’t properly fuel these engines. Kevin McLelland of our sister magazine, Chevy High Performance says you can use the stock in-tank pump to feed a Bosch PN 044 pump mounted close to the tank to get the proper pressure. To keep the proper 58spi, run a filter/regulator assembly from a ’99-’03 C5 Corvette (GM PN 10299146) in front of the Bosch pump with a 5⁄16-inch return back to the top of the fuel tank. Tony Pellegrino of GenRight Off Road says a factory YJ fuel pump will supply more than enough pressure to feed these engines. Again, using the C5 filter/regulator assembly is the best way to regulate the fuel pressure.

Wiring: Check elsewhere in this story, but a myriad of options exist from Painless Performance, Hotwire Auto, Holley, MAST Motorsports, Turn Key Engine Supply, Pacific Fabrication, and a host of others. Options are out there to run full closed-loop factory ECU setups to custom-tuned open-loop with proprietary or MEFI 4-type ECUs.

Engine Displacement Years/Vehicles Power (hp/torque) Notes
LS1 5.7L ’97-’04 Corvette, Camaro, Firebird, GTO 305/395 (Camaro) 350/395 (Corvette) Aluminum block/heads; cable-operated throttle
LS2 6.0L ’05-’07 Corvette, GTO, Chevy SSR, Trailblazer, Cadillac CTS-V 400/400 Aluminum block/heads; electric throttle
LS3 6.2L ’08-present Camaro, Corvette 430/424 Aluminum block/heads; electric throttle
LS6 5.7L ’01-’05 Corvette, Cadillac CTS-V 385/385 (’01) 405/400 (’02-’05) Aluminum block/heads; hollow valves; improved intake; cable-operated throttle
LS7 7.0L ’06-’11 Corvette Z06 505/470 Aluminum block/heads; monster valves; electric throttle
LS9 6.2L ’09-present Corvette ZR1 638/604 Aluminum block/heads; Eaton supercharger; electric throttle
LSA 6.2L ’09-present Cadillac CTS-V, 2012 Camaro 556/551 Aluminum block/heads; Eaton supercharger; electric throttle
LR4 4.8L ’99-’06 GM light truck & SUV 270-295/285-305 Iron block/aluminum heads; cable-operated throttle
LY2 4.8L ’07-present GM light truck & SUV 295-302/305 Iron block/aluminum heads; electric throttle
LM7 5.3L ’99-’07 GM light truck & SUV 285-295/325-335 Iron block/aluminum heads; cable-operated throttle
LM4 5.3L ’04 Chevy Trailblazer, GMC Envoy, Chevy SSR 295/335 Aluminum block/heads; cable-operated throttle
L33 5.3L ’05-’07 GM extended-cab pickups 310/335 Aluminum block/heads; high-output version; cable-operated throttle
L59 5.3L ’02-’07 GM light trucks & SUV 285-295/325-335 Iron block/aluminum heads; Flex-fuel version (more complicated for swapping); cable-operated throttle
LH6 5.3L ’05-’09 GM light truck & SUV 315-320/340 Aluminum block/heads; VVT and active fuel management; electronic throttle
LY5 5.3L ’07-present GM light truck & SUV 315-320/340 Iron block/heads; VVT and active fuel management; electronic throttle
LMG 5.3L ’07-present GM light truck & SUV 315-320/340 Iron block/heads; VVT and active fuel management; Flex-fuel version (more complicated for swapping); electronic throttle
LC9 5.3L ’07-present GM light truck & SUV 315/335 Aluminum block/heads; VVT and active fuel management; Flex-fuel version (more complicated for swapping) electronic throttle
LQ4 6.0L ’99-’06 GM light truck & SUV 300-325/360-370 Iron block/aluminum heads; cable-operated throttle
LQ9 6.0L ’02-’07 Cadillac Escalade, Chevy Silverado SS, Silverado HO-edition 345/385 Iron block/aluminum heads; cable-operated throttle
LY6 6.0L ’07-present GM light truck & SUV 312-353/373-383 Iron block/aluminum heads; electric throttle
L92 6.2L ’07-present GM SUV & GMC Sierra Vortec Max package 395-403/415-417 Aluminum block/heads; high-output version; VVT; electronic throttle


Pacific Fabrication
Morgan Hill, CA 95037
Summit Racing
Akron, OH
Chevrolet Performance Parts
Detroit, MI 48232
Royal Oak, MI 48067
Advance Adapters
Paso Robles, CA 93446
Hotwire Auto
Mena, AR
Howell Engine Developments
Marine City, MI 48039
Mast Motorsports
Nagodoches, TX 75964
Murray, UT 84107
EFI Connection
Ron Francis Wiring
Chester, PA 19013
Turbo City
Orange, CA
Lingenfelter Performance Engineering
Decatur, IN
Novak Conversions
Logan, UT 84321
Burnsville Off-Road
Burnsville, MN 55337
Street & Performance
Mena, AR 71953
Gen Right
Simi Valley, CA 93063
RJM Injection Technologies
Speed Scene Wiring

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