Jeep YJ LS Swap Kits - Upgrade to an LS V8 Engine

Introducing the Jeep YJ LS Swap

The Jeep Wrangler YJ was manufactured from 1987 to 1995. It came equipped from the factory with AMC's 4.2L straight six engine or the 2.5L AMC 150 I4 engine. While decent for their time, most YJ owners these days are looking for a more modern, fuel efficient, and powerful engine to drop into their classic Jeeps.

This is where the GM LS series engines come into play. GM produced these technologically advanced all-aluminum small block V8 engines from 1997 to present day, with some of the most popular versions being the 4.8L, 5.3L, 5.7L, 6.0L, and 6.2L variants.

Benefits of the LS Swap

There are many benefits to performing an LS swap into a Jeep YJ:

• Increased horsepower and torque - The LS engines produce significantly more power than the old AMC powerplants
• Better fuel economy - Despite being larger engines, LS engines can get equal or better mpg thanks to advanced technology
• Reliability - The LS platform is time-tested and known to be very reliable with proper maintenance
• Affordability - Due to being mass produced, LS engines are plentiful and affordable on the used market

Choosing an LS Engine

When selecting the right LS engine for your YJ swap, keep factors like intended vehicle use, emissions compliance requirements, engine availability, and budget in mind.

Here are some of the most common LS engine options for a Jeep swap:

• 4.8L (293 cu-in) - The smallest LS V8, good power gains over stock YJ engine
• 5.3L Vortec (327 cu-in) - One of the most popular choices, readily available and affordable
• 6.0L LQ9 or LQ4 (364 cu-in) - Beefy iron block, excellent for off-road use

Jeep YJ LS Swap Kits

Many companies offer complete swap kits that include all the parts and components needed to put an LS engine into a Jeep YJ. Here are some top options:

Novak Conversions YJ LS Swap Kit

Longtime Jeep experts Novak offer what is likely the most fully developed YJ LS swap solution on the market. Their kits are engineered specifically for this vehicle application and use many exclusive Novak designed mounts, brackets, adapters and crossmembers.

Some Novak YJ LS swap kit features include:

• Engine mounting plates attach directly to factory frame positions
• Oil pan specially designed for YJ chassis clearance
• Fuel pump and filter mounting assembly
• Custom driveshafts balanced and rated for V8 torque

Novak kits are complete less the donor LS engine itself. Their set-up allows the use of either 4.8L through 6.0L Gen III/IV engines, both the iron block trucks engines or the aluminum versions.

Advance Adapters LS Swap Kit

Advance Adapters also offers a well-regarded solution for putting an LS in a YJ. Some of the highlights include:

• Engine mount plates for secure V8 positioning
• Oil filter relocation for better header/steering clearance
• Multi-position transmission crossmember
• Polyurethane engine and transmission mounts

Their kits accommodate LS Gen III and Gen IV V8s from 4.8L to 6.2L engines. Like Novaks set-ups, you supply the actual LS engine while Advance supplies all the critical parts for safe installation.

Other LS Swap Kit Options

There are also smaller companies like LsYjSwap and Iron Rock Off-Road that offer swap kits for Jeep YJ LS conversion projects. Shop around for the solution that best fits your project budget, engine choice, and requirements.

Installing the Swap Kit

The actual job of installing a YJ LS swap kit will likely take an experienced mechanic a full weekend if no major issues are encountered. Make sure to use a factory service manual for reference and have all specialist tools on hand.

Some key steps involved in the swap include:

• Removing existing drivetrain components like engine, transmission, transfer case
• Installing engine mount plates and adapter brackets
• Fitting oil pan and front sump oil pump pickup
• Installing modified exhaust manifolds or LS swap headers
• Installing fuel pump module and lines
• Connecting drive shafts and crossmembers
• Reinstalling modified cooling components

An LS swapped Jeep YJ is an awesome upgrade that greatly enhances the 4x4's performance and enjoyment. While the initial investment is significant, the result is a nearly new rig with modern V8 power.

FAQs

What transmission works best for a Jeep YJ LS swap?

The 4L60E and 4L80E automatics, as well as the NV3500 and NV4500 manual transmissions, tend to work best for LS swaps in the YJ. The auto boxes handle the torque nicely while the manuals give great driver control.

Do I need to upgrade my axles when I LS swap my YJ?

Not always, but it recommended for off-road use. The additional power and torque of an LS can shorten the lifespan of the stock Dana 35 axles. Upgrading to stronger units like Dana 44s or Ford 8.8” axles is advised.

What needs to be modified to fit an LS in a Jeep YJ?

Typical modifications include custom engine mounts, oil pan alterations, modified exhaust manifolds, fuel system upgrades, adapted cooling system components, and custom drive shafts. Quality swap kits handle most of the necessary changes.

Is the LS platform CARB legal for my Jeep YJ?

Yes, certain truck LS engines like LQ4 and LQ9 motors can be adapted to the YJ drivetrain and retain emissions legality. Professional swap companies offer CARB certified packages.