Subaru Conversion

Subaru 2.5L Naturally Aspirated Gas Engine

Total Price: $16,000-$19,000   Timeline: 4-8 wks   Output: 165hp 170ft-lb torque

Utilized in the uber popular and award winning Subaru Outback and Forester models, this engine conversion may be one of the most, if not the most, popular conversion for Vanagons out there. 


This is a single overhead cam, horizontally opposed 4-cylinder engine displacing 2.5L. Stock tuning produces between 165-175hp and around 170ft-lb of torque.  This engine produces great power throughout its RPM range and produces enough power even on heavier rigs at higher elevations. It also generally provides better gas mileage over the Vanagon stock engine.


This conversion is popular for a reason. It’s more reliable than the stock waterboxer and produces a fantastic amount of power. With this engine in your Vanagon it’ll be like driving a completely different vehicle. 


Occasionally used in light aircraft, this engine’s reliability, when properly rebuilt provides many thousands of miles of reliable service. Because these engines come rebuilt, it is important to ensure that the rebuilder uses high quality parts and provides a good warranty to our users. All of our engines are sourced from Subaru of North America which receive a factory spec overhaul that Subaru's stringent quality standards.


This incredibly powerful and quite reliable engine is great for road trippers who are looking to pull hills with ease, drive at highway speeds, and be able to comfortably drive at high elevation. Heavier rigs would do well with this conversion. Parts are readily available in North America and are more cost effective than the Vanagon stock parts. Serviceability is also easy to attain. Please see our Recommended Upgrades below if this is the engine conversion you choose.




This conversion is a good choice for those looking for an adventure rig to use as their family get-away rig or as their daily driver for around town. A naturally aspirated engine, the Subaru 2.5L (EJ25) looks as if it belongs in the Vanagon engine compartment. No modification of the deck lid is required.


Through research, experience, and constant inquiry with owners running these engines, we have found a reliable source for our rebuilds. The engines are all prepped by Wild Westy in Boulder, Co. and come with 2 year 24,000 mile warranty. We've sourced only parts and conversion components that reduce wear, reduce these engines overconsumption of oil and keep them running reliably for their owners. For optimal performance and longevity, we recommend using premium grade fuel.

The landscape for engine conversions is littered with shops offering to turn your old tired Vanagon into a mean, snarling Subaru converted beast. Buyer beware. Not all shops source their engines the way we do. It is key to buy rebuilt engines only from shops specializing in rebuilding Subarus to handle the additional weight and aerodynamic drag of the Vanagon. 


Key Advantages

  • Support for engine across North America

  • Quiet, More Powerful and Reliable

  • Inexpensive and easily available maintenance items

  • Fits under Vanagon engine deck lid

  • Engine Rebuilt for Vanagon Specific Applications

  • Turn Key System

  • 18 months / 18,000 mile Warranty

  • Better Gas Mileage (16–22mpg)*

*Mileage depends on driving style, weight of Vanagon and transmission gearing

The Pricing


Bus Werks Subaru
Engine Conversion

Includes Rebuilt Subaru 2.5L NA Gas Engine, conversion kit
and Mountain Bus Werks labor.

$16,000 -


*In some cases, labor costs may vary.


Additional Considerations


It’s important to remember that the Vanagon is at best a 25 year old vehicle. Heavy modifications and conversions to new systems can place strain on older systems that have not been modernized or replaced in your beloved van. We know from experience that there a number of things to take into account when looking at engine conversions of any sort.


We highly recommend that when going with the Subaru Conversion to consider rebuilding/overhauling the transmission at the same time. The added torque and power of the Subaru motor can put additional strain on your stock Vanagon transmission. This is especially true in 2WD automatic Vanagons. Though not necessary to overhaul the transmission at this point, it is worth considering if only to reduce future potential failure points along the drivetrain.

In addition to rebuilding the gearbox, we highly recommend overhauling the coolant system and related components. The stock radiators and coolant pipes in your Vanagon are likely warn out it's best to replace those parts while everything in the engine bay is taken apart.

Although we try to ensure that any conversions we do are approached more as holistic systems rather than simply looking at power outputs, with the Subaru conversion it is not possible to source new parts since, by definition, these engines and their management systems are used. We do however wire up our Subaru conversions to an engine management and monitoring system so any issue with your engine can be easily diagnosed by Subaru technicians around the country.

Recommended Upgrades