Do All Diesel Engines Have Turbos?

Diesel engines, like all internal combustion engine types, require a mixture of fuel and air to flow through the intake system to operate. Modern fuel delivery systems use injectors with the ability to deliver substantial amounts of atomized fuel. That makes the volume of air that the engine can suck in the limiting factor with naturally aspirated engines.

The origins of diesel-powered vehicles are tied to large trucks designed to haul heavy loads of freight. Early diesel engines featured large displacements and little regard for the emissions they produced. Toward the latter part of the 20th century, government regulations imparted more concern for emissions, fuel prices increased, and the need to haul more freight per load combined to create the need to modernize diesel engine technology.

The need for lower-emission, more-powerful, and highly fuel-efficient diesel engines was answered by the forced air induction provided by turbochargers. By the 1970s, improved turbo technology and reliability made them more acceptable to consumers, marking the decline of the naturally aspirated diesel engine. While the majority of diesel-powered vehicles on the road today use turbos, not all diesel engines have them.

Most of the naturally aspirated diesel engines produced today are used for agriculture, industrial use, and powering generators. Since farm tractors, irrigation systems, and generators aren't subject to emissions controls and don't generally require the same power-to-weight ratio as heavy-duty trucks and commuter vehicles, the simplicity and efficiency of naturally aspirated diesel engines suit them well.

That's not to say that automakers haven't tried to use non-turbo diesel engines in production automobiles. However, compared to the fastest diesel-powered cars, models without turbos, like the diesel-powered Chevrolet Caprice, flopped with large-scale consumer disappointment.

If you're looking for a naturally aspirated diesel engine for a project, such as a go-kart, minibike, or lawn tractor upgrade, you can actually buy them on Amazon. For example, one highly rated horizontal shaft four-stroke diesel engine available on Amazon is a single-cylinder 196cc model priced at $184. However, brands like Kubota, Yanmar, and Bison likely produce small diesel engines with higher quality components designed to deliver longer service life.