Wrangler JK v8 Conversion

Turn-Key or DIY Jeep Hemi Engine Conversions – Your Call!

It’s a bright morning. You jump in your Wrangler JK. Trembling with anticipation, you turn the key and 400 horses rumble to life.This is when you realize, CARB Legal Hemi Conversion Kits from Jeep Speed Shop in Northern Sonoma County delivers… big time

Since 2004, Jeep Speed Shop has been creating exhilarating Wrangler JK transformations along with Dodge makeovers. Owner Todd Custer has intermixed a diverse 30-year automotive career in research, design, and mechanics to deliver a 50-state-legal 5.7L Hemi Conversion Kit.

And, as you know, if it is legal in California, it is legal in all other states. Yes, the California Air Resources Board has given Jeep Speed Shop specific approval for their VVT JK Truck Hemi Kit.

JSS Hemi Conversion Swaps

Jeep Wranglers are a cultural phenomenon. First introduced in 1986, the “Experts” gave little hope to its longevity. Who would ever want to buy an army vehicle anyway? But, the Wrangler has been refined and polished through the years and, though the 4-Wheeler remains woefully underpowered, it has developed a large base of loyal jeep enthusiasts. 

A Wrangler Hemi Conversion from JSS can double or even triple horsepower and torque ratings. Though hundreds of jeep conversion shops across the country are equipped to handle engine and transmission swaps, Jeep Speed Shop is the only custom shop that can deliver a 50-state emission legal Jeep Wrangler 5.7L Hemi Conversion.

JSS recommends two conversion options:

  1. Turn-key: includes a new 5.7L engine and new automatic transmission with installation and fine-tuning performed at JSS. 
  2. DIY option: buy your own CARB legal Jeep Hemi engine conversion kit and bring your own garage. 

In the kit you’ll find a 390HP truck-sourced 5.7L Hemi generating 407 ft-lb of torque. This upgrade almost doubles the performance of your Jeep. But power isn’t the only perk. The engine also features a cast iron block for durability, along with VVT and MDS technologies for maximum efficiency.

Full Installation by Jeep Speed Shop

Conversions are performed at JSS in Sonoma County, California. Full conversion includes a new iron-block crate 5.7L Hemi and new 545RFE 4-speed automatic transmission. If you prefer, JSS can procure a low mileage truck Hemi engine and used transmission.  


A new custom programmed PCM is a centerpiece to the CARB Legal Kit. This small but important part controls a majority of the electronic systems on your Wrangler. The PCM is set by JSS to improve air-fuel, idle, variable valve timing, and other electronic control systems.

  • The 5.7L Hemi crate engine is perfect for swapping into a 2007 to 2011 Wrangler JK. Introduced in 2003, the GEN lll Hemi was well received by the market and recognized as one of the “10 best” by Ward Magazine. The original block needed to be redesigned early in the production cycle, accommodating the technological advantage of VVT.
  • Jeep Speed Shop specifies an original nodular iron block for its strength and durability.
  • The original iron-block 5.7L Hemi VVT engine delivered over 400 ft-lbs. of true torque from the factory and has been effectively trouble-free since its launch
  • Installed with every iron-block JSS Hemi engine is Chrysler’s Multi-displacement system. This technology is required by JSS to help with power and fuel efficiency.

The conversion kit also includes a new factory 545RFE transmission. This Chrysler made tranny has been in constant production since its introduction in 2001. Many mechanics consider the 545RFE one of the absolute best transmissions available. Among other improvements, Chrysler enhanced first gear response for improved acceleration. The 545RFE transmission is well suited to accommodate the high torque ratios and extreme stresses of Hemi engines.

  • JSS Conversion kits include a new alternator, ac compressor, and power steering pump. Note that all belts, bolts, cabling, and hoses are included.

The Full Swap Kit includes a high-performance Hayden Transmission Cooler with their patented “Flow Path Design” for internal heat transfer. The cooler can handle a GVWR of up to 30,000 pounds and is well-suited for the additional heat generated by the Hemi engine.

A new radiator is installed, along with heavy-duty upper and lower hoses. JSS improves overall performance with the addition of a Flex-a-lite engine cooling fan.

  • Flex-a-lite is synonymous with innovation and quality, and was the first company to introduce an electric cooling fan in the US.

Custom Add Ons

Jeep Speed Shop is world-renowned for its custom work involving CARB Legal Hemi Conversion Kits. However, if you want to go full beast-mode with your Wrangler, JSS can handle any type of conversion or upgrade.

Maybe a Diablo tuner is what your Wrangler needs. Instantly add torque and horsepower with a next-generation Diablo i3. Your Wrangler will have better throttle response and fuel economy. JSS engineers can make the upgrade a reality.

  • Go full beast mode with your Wrangler and have JSS install a custom lift-kit.

Imagine waking up that same crisp morning to see your Wrangler with 700 HP and a 2.5” lift.

DIY Conversion Option

Jeep Speed Shop can also provide all the ingredients needed for you to turn your Wrangler JK into a monster in your own shop.  Jeep Carb Legal VVT Truck Hemi Kit 2007 to 2011 is a complete conversion, without the engine and transmission.

If you are ready to tackle a conversion in your garage, read the new DIY guide prepared by the experts at JSS. The guide is complete, with step-by-step instructions and videos.

Study the JSS product list carefully. Make sure the parts you source from a salvage yard match the specifications of the conversion kit.The Jeep Wrangler is no stranger to DIY conversions. Many swaps have been performed in shops and garages across the country and consequently, there is plenty of information, tips, and how-tos for the home mechanic.

  • Always be prepared for complications.

If you are attempting this conversion in your garage, saving money is probably a priority. Here are a few tips that may stave off a headache or two:

  •         Buy a used low mileage 5.7L Hemi engine. Any well-stocked salvage yard should have plenty. Make sure to pressure test. Cast-iron blocks are prone to core-shift, make sure to perform a sonic test
  •         Stock transmissions can take the power of a hemi. However, you need a Hemi bell housing and torque converter. Opt for a factory rebuild if the unit is within your price range.
  •         The beauty of the JSS kit is that there will be no fabricating or welding needed
  •         The new kit provides an exhaust system which has been pre-mated to the supplied engine mounts
  •         Pay close attention to oil filter placement
  •         Budget for a good pair of fans
  •         Old accessories probably won’t work with the new engine


Jeep Speed Shop has given Wrangler crazies all the horsepower and torque they can dream of in a conversion package that passes California smog tests. No other conversion shop in the country can boast this quality.

Early in the life of Jeep Speed Shop, Todd and his engineers worked on Chevy LS conversions. Years were spent trying to stuff round pegs into square holes. However, California constantly upped the ante. Year after year, smog restriction compliance became more difficult. They realized it was not worth the effort to continue LS and other similar conversions. Therefore, Jeep Speed Shop has turned its considerable talent toward Wrangler conversions, and it has paid off.

Conversion Kits are only one solid feature of Jeep Speed Shop.

JSS is a full-service Wrangler shop, taking care of everything from oil changes, to changing a clutch. JSS uses mostly OEM Chrysler parts in their conversion kits. However, the company represents some of the finest suppliers in the industry.

  •         Alloy Axles
  •         Bilstein
  •         GenRight Off-Road
  •         Magnuson Superchargers
  •         Rock Krawler Suspension

There are exciting innovations coming from the Wrangler experts at Jeep Speed Shop. Imagine an 8-speed shifter in your Wrangler JK with a mind-blistering Hemi engine. Call us at (707) 338-3154 to learn more or if you have any questions. You can also connect with us by completing our Contact Us page.