5 Common Myths About Diesel Engines


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We've identified five common myths about diesel engines that we're happy to debunk! Learn some of the misconceptions about fuel economy, environmental impact, cold-starts, and more. These are some of our most asked questions!


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1. Are Diesel Engines Worse for The Environment Than Gasoline?


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Diesel engines have a bad reputation for being dirty and bad for the environment because you can visibly see the emissions leaving the exhaust. Diesel engines do emit nitrogen compounds into the air, but newer engines actually produce a lower amount compared to gasoline motors because of EPA regulations.

New emission requirements from the Environmental Protection Agency (EPA) and technology upgrades have led to much lower emissions and a cleaner output overall. Engine models from 2007 and up have advanced exhaust systems that heavily reduce this output. These systems can reduce vehicle emissions up to 90% and nitrogen compounds by 25-50%. (U.S. Energy Information Administration, 2019) You should never delete your emissions system. Learn why in our detailed blog about Diesel Engine Emission Requirements.


2. Do Diesel Engines Have Poor Fuel Economy?


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What you may notice while shopping for a new vehicle is that diesel engines actually deliver great mileage! Compared to similarly performing gasoline vehicles, they typically get 20-30 percent further on a gallon of fuel. For a turbo-diesel, most commonly you'll find 25 percent greater fuel efficiency.

The reason for the better fuel economy is mainly because of these two factors:

  • Differences in gasoline and diesel fuel
  • Differences between gasoline and diesel engines

There's one big difference between the two types of fuel.  It's that one has more energy per gallon of fuel. When comparing the calorie content of a gallon of gas versus a gallon of diesel fuel, you'll find that diesel has far greater calories. Gasoline approximately has 31,000 calories per gallon, while diesel has around 35,000. More calories means more energy!

The other main contributor for the higher fuel efficiency of diesel vehicles is the differences in engines. Diesel engines have a longer compression stroke, allowing more torque to be created. You can read more about how different strokes contribute to greater engine power and efficiency in our blog, How Does a Diesel Engine Work?


3. Are Diesel Vehicles More Expensive to Maintain?


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One of the main benefits of diesel vehicles is the longevity and durability that they provide. If you look at a surface level, high initial prices for diesels may turn you away. However, research done by the University of Michigan Transportation Research Institute found that you'll save up to 27% on lifetime fuel costs compared to the gasoline equivalents. When comparing diesel pickups to the gasoline equivalents, they even had up to 70% higher resale values.

You'll experience failures much less frequently than their gasoline counterparts. Not only that, you'll also get better fuel economy. For information on increasing the longevity of your engine, read our 5 Tips to Help Your Diesel Engine Live Longer.


4. Do Diesel Engines Struggle to Start in the Winter?


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In freezing weather conditions, gasoline has a much easier time igniting than diesel fuel. This doesn't mean diesels can't start in the winter, however. Modern technologies have been able to make cold-starts much more effective in diesel engines.

One of the essential cold-weather improvements is a block heater. The purpose of these heaters is to keep the engine block warm even when the vehicle is turned off. Block heater improvements combined with the use of a glow plug makes low-temperatures less of a problem.

Cold weather also drains the life of your battery. A worn-out battery can affect the function of your glow plugs since it supplies the energy to get them working. To prevent your battery from draining in cold weather, you could invest in a battery warmer to keep things toasty.

If you want to avoid problems with your diesel engine in the winter, there are a few precautions you can take:

  • Make sure your batteries are healthy
  • Keep your glow plugs/glow plug relay in check
  • Check for proper intake grid heater function
  • Invest in a battery warmer


5. Do Diesel Engines Perform Poorly at High Elevations?


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Because of the thin air available at high-altitudes, there's a myth that engine performance is significantly worse for diesel engines. The reality is, gasoline engines are the ones that struggle, and the efficiency of diesels isn't really affected. This is because the fuel-to-air ratios in gasoline motors are very precise. The air in high elevations is thinner, meaning to maintain the correct ratio, less fuel is added, affecting performance. Diesel engines can have a less precise fuel-to-air ratio and still function well. They also pull more air and fuel into the combustion chambers overall, delivering a higher power output.

The turbos in diesel vehicles also contribute to maintaining the fuel-to-air ratio. It's able to force more compressed air into the combustion chamber by utilizing the exhaust output from the engine. We have a massive selection of OEM-quality turbochargers available on our website. You'll also save up to 50% off OEM prices by shopping with HHP!



Need help with your diesel engine? Our certified techs can help! Call 844-304-7688 to speak to one today, or request a quote online.