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Jeep Wrangler Diesel Conversion

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Diesel Conversion

Bruiser Conversions is setting a new standard in power for Jeep JKs. With the Cummins 4BT Turbo Diesel Power Plant, Jeep enthusiasts can now boast improved performance in torque, fuel economy and fuel capability… and of course, the coolness factor of a diesel engine. In fact, the 4BT engine is capable of producing 400 ftlbs of torque at 1700 rpms.

Factory Quality Install

We put a high emphasis on making our conversion look and function like a factory install. We used as much of the factory components as possible to ensure it functions as smoothly as when you bought it. All gauges and instrumentation works correctly with the exception of cruise control, which can be modified to operate correctly. Our installation only takes 10 business days to complete and you can get it done at one of facilities close to you.

Detailed Conversion Information (click to expand)

The years of the Jeep Wrangler model that can be converted at present are 2007 to 2011. We remove the stock engine and transmission and replace it with a Cummins 4BT and stronger transmission. Below we will discuss some of the kit components in greater detail.

The kit utilizes a mechanical bell crank assembly with Lokar stainless throttle and t.v. cable for transmission (also known as a kick down cable). In addition it uses a bracket for floor board to accept a manual throttle pedal.

Our custom A/C and alternator bracket enables the conversion and reuse of the existing AC compressor and alternator from the 3.8L. The serpentine belt is upgraded to an 8-groove belt, along with, an upgraded 8-groove A/C clutch and 8-groove alternator. The a/c lines are custom to retrofit to the factory compressor in its new location.

The battery tray is custom made to relocate the position of the battery and the fuse /relay box for proper clearance of the cold air intake and turbo. The wiring harness is completely re-engineered to control all engine functions as well as communicate with factory ECM through a S.I.M. (Systems Integration and Management) computer.

The engine mounts are engineered to remove most of the vibration from the 4BT. This is accomplished by utilizing a fluid filled mount located in the custom built engine mounting bracket assembly. The assembly itself is designed to maintain the engine’s torque and remove all harmonics.

The factory gear driven power steering pump for the 4BT is utilized and conversion high pressure and return lines are custom made to connect to the factory power steering gear. The pump also makes enough pressure to operate all after market ram assist or full hydraulic steering arrangements; this is because it did control a hydro assist system.

The factory radiator and fan assembly is reused because the 4BT does not require an extreme cooling system to maintain the proper temperature range of 180 degrees. The lower water neck is replaced with a custom built unit that allows you to reuse the factory lower hose from the 3.8 and the upper hose is replaced with a new unit.

The braking system is controlled by a billet housing custom vacuum system.

There are two options for transmission. For those wanting an automatic transmission, we offer the 4L60E with Compushift. For those wanting a manual application, we offer the NV4500. Both of these transmissions are bulletproof units that can handle the extra torque of the 4BT.

The transmission is mated to the factory transfer case through a custom adapter and newly broached tail-shaft assembly. The cooling lines are custom for transmission, as well as, all brackets to attach factory shifter cable to transmission and transfer case. This also allows you to reuse the existing transmission and transfer case shifters in their factory positions.

The factory mount is used to mate with the factory cross member through a custom mounting bracket, which allows you to re-use the factory length drive shafts with up to a 6 inch lift.


3.9L Cummins 4BT Turbo Diesel

The 4BT is one of most proven reliable diesel engines in the world. If well maintained, it is not uncommon for these engines to last 350k – 500k miles. They are also a very common engine making it easy and affordable to repair should anything break.

Our conversion includes a brand new 4BT from the manufacturer, though it can be substituted with a remanufactured/used engine if the client desires.

We have a variety of power options for those seeking to upgrade their application.

4BT Specs (click to expand)

Our Applications:
2007-2011 Jeep JK
1997-2006 TJ Wrangler and Unlimited
1987-1995 YJ Wrangler
1976-1986 CJ

Inline 4 Cylinder Turbo Diesel

3.9 L, 239 Cubic Inches

4.02 inches

4.72 inches

Compression Ratio:

Turbo Charged, Non Intercooled

Engine Weight:
725-765 lbs

Oil capacity:
10 Quarts

105-170 Hp@ 2300 RPM *

265-420 lb-ft@ 1600 RPM*

*HP&Torque Ratings vary by application

Bosch VE Rotary Pump 4BT Application Upgrades (click to expand)

  1. Bruiser fuel pin 40-60 HP / 80-100 ft/lb
  2. Prince of darkness injectors 30-50 HP / 80-100 ft/lb of torque
  3. Turbo upgrade H1C 30-50 HP standard
  4. Different Turbo chargers and exhaust housings can be utilized to enhance reaction time for quick spooling example 12 cm exhaust housing w/ H1C gives quicker spool up which gives better bottom end. There are many different applications for different driving characteristics.
  5. Injectors- Stage 1 (Prince of darkness) Injectors increase 30-50 HP / 80-110 Ft/lbs. of torque
  6. Many factors determine Horse Power and Torque. With customer technical   support we can determine what the best option is for your application.
  7. Camshaft upgrades are available.
  8. Several different transmissions including manual and automatic depending on customers desired application.
  9. Valve springs, push rods, rocker arms, custom exhaust manifolds
  10. Bruiser Down tubes 2.5 inch to 3 inch
  11. Spring upgrades to 3200 rpm for injection pump
  12. Remote Fuel filter and water separator relocation brackets and assemblies
  13. Remote Oil filter Relocation brackets and assemblies
  14. Air to Air cooler, After cooler and all accessories with Bruiser cone style K-n-N air cleaner assembly
  15. Bruiser air box
  16. Snorkel assemblies available

P-7100 Pump 4BT Application Upgrades (click to expand)

  1. P7100 Inline Pump- Fuel Plate 20-110 hp / 60-215 Ft/Lb of Torque
  2. Prince of Darkness injectors 30-50 HP / 80-100 Ft/lb of Torque
  3. The rest is the same as 4BT VE Pump Application.

Upgraded Transmission

4L60E - This automatic transmission is capable of holding 850 ft. lbs. of torque.

NV4500 - This manual transmission is a proven warrior. It has been used predominately in diesel applications for years and is one of the best manual transmissions ever produced.

Off-road Capability

Torque comes in at a very low rpm enabling excellent control of vehicle with minimal tire spin and excellent traction in an off camber situation caused by added weight.

Economically Friendly

Economy is a plus; in our tests, a correctly modified jeep unlimited can achieve 28 mpg around town and upwards of 30 mpg on the interstate. Depending on build sheet and modifications to engine as well as tire size and gear ratio.

Multiple fuel capability, the bruiser has the capability to run on several different types of fuel with little or no modifications, such as waste vegetable oil, bio-diesel etc.

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