Why Don't Small Turbo Engines Get Good Gas Mileage? (Real World)
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In attempts to improve fuel economy, many companies are choosing to downsize and turbocharge engines. These small turbo engines tout the power of larger engines, but with much better fuel efficiency. You may notice however, your real world fuel economy may not always match up with the EPA numbers provided on the vehicle's monroney sticker.

Why is this? Well while downsized turbos do have many advantages, such as less moving parts, less weight, better packaging, lower frictional losses, and lower pumping losses, once the vehicles start to get into boost, that efficiency can be significantly lower. This video will discuss fuel enrichment and why it's necessary for high boost engines in order for them to run reliably.

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Comments

    • scanspeak00
      scanspeak00

      Please do a real world comparison of a NA engine and turbo engine of equal power. Hard to get honest numbers from manufacturers.

      about 1 day ago
    • newest bear
      newest bear

      Know what's efficient, walking or biking.

      about 6 days ago
    • JD Simons
      JD Simons

      You pump more air, you must burn more fuel its that simple.

      about 7 days ago
    • Stiv Mwaniki
      Stiv Mwaniki

      A video request. I would like to know how exactly a big truck with more than a 1000 lb:ft of torque and close to 400 HP like the Actros 2640 LS still not as fast as a small sedan with a half the HP and even a quarter of the touque even without the truck hauling any cargo.

      about 7 days ago
    • B A
      B A In reply to Stiv Mwaniki

      @Stiv Mwaniki
      1. How much do the truck and car weigh?
      2. What is the total gear ratio for each gear in each vehicle?
      3. What does the torque curve look like for each vehicle?

      about 7 days ago
    • Francesco
      Francesco

      A turbocharged engine will get you better gas mileage than a naturally aspirated engine, it will also give you better power compared to its naturally aspirated counterpart. Be wary however, it cannot give you both simultaneously.

      about 7 days ago
    • Matt Stimson
      Matt Stimson

      Naturally aspirated engines also go rich with more throttle...

      about 8 days ago
    • Sammy Sampson
      Sammy Sampson

      My 1.0 Liter Ecoboost Focus with an auto trans gets well over 40 mpg on the highway and over 35 in city. Tell me again, please how they are not efficient...

      about 9 days ago
    • Commentor1
      Commentor1

      0:50 The assertion that a small turbo engine has less moving parts than a larger engine (for instance, a turbo 4 vs an NA V8) is disingenuous. Yeah the V8 has more cylinders, valve springs, etc., but the V8 engine is way less complex, is subjected to way less stress (no boost), and will probably be the more reliable of the two.

      about 9 days ago
    • Stephen Cannon
      Stephen Cannon

      Also remember regardless of engine, 3/4/5/6/8 cylinder, turbocharged/supercharged or normally aspirated. Full tank will kill fuel mileage. You are adding full fuel, and for a family road trip all the occupants and cargo. As you drive and the fuel gets burned off your MPG should improve.

      Also those who think driving 70-80 MPH with A/C off and windows down......wrong in most cases. The parasitic drag and turbulent airflow around the window housings will most likely off set any fuel savings and may in fact cause even lower MPG along with increased ambient air temperatures and noise.

      Think driving with windows down and A/C in thinking you are still getting the cold air from the vents. WRONG. Again: you might get away with it a few times but eventually the A/C compressor will fail. The compressor is trying to condition outside air at one central point (internal vents). Trying to compensate for the warm air coming in from the windows the compressor will eventually give up the ghost. I would pretty much guarantee they a compressor is much more expensive than the extra fuel you might use driving with A/C on.

      about 22 days ago
    • Vincent Sluga
      Vincent Sluga

      A 70 hp engine can move a thousand pound car nicely. A 70 hp engine with a turbo can move a 3,000 pound car good too, but sucks the fuel. Anyway, it’s like the new Silverado. Small 4 cylinder gets the same gas mileage as the V8.

      about 23 days ago
    • Billy Graham
      Billy Graham

      Theoretically a long stroke engine running on gasoline would be very efficient as gasoline is a slow burning fuel. High torque too. I wonder why auto manufacturers don’t make such engines? A turbo should only come on when ultra power is needed, like passing a truck on a 2 lane highway or climbing a mountain at high altitude.

      Of course, I also wonder why American cars are so poorly engineered — are the people controlling the auto industry in America trying to destroy it? Looking like it to me. I’m not an engineer but I do a better job engineering and designing a car...

      about 24 days ago
    • PeterGriffin4200
      PeterGriffin4200

      Honda needs to take out the turbos in the new Accords. The 1.5 and 2.0 turbo will be unreliable because too much force induction in a small engine will wear it quicker. Honda needs to get a naturally aspirated 2.4 Earthdreams 4cyl with 200hp and bring back the 3.5 j series V6 with 300hp. Those will be bulletproof cars.

      about 24 days ago
    • Paul Kojack
      Paul Kojack In reply to PeterGriffin4200

      They are never tuned to give that much boost stock. Sure it puts a little extra kick in it, but i really doubt it decreases reliability much if you drive it normally. Turbo engines have proved to last just as long as naturally aspirated motors when properly maintained. I just don't like the added complexity since a regular 4 cylinder does the job just fine, but i wouldn't worry about it wearing any quicker. All haulers have big turbos running tons of boost and they do more miles than any vehichle on the road.

      about 24 days ago
    • Greg Schlegel
      Greg Schlegel

      Okay 👌

      about 24 days ago
    • Kneek Knocks
      Kneek Knocks

      This video has created a lot of comment controversy, most of which the information is taken out of context or misunderstood. I think everyone should leave the engineering to the engineers.

      about 24 days ago
    • Joel Sadler
      Joel Sadler

      This is why my 1150kg Ford Fiesta ST 2.0 is actually good on fuel. It’s large for the car size so it’s not working hard most of the time and it’s N/A so it’s never using loads of fuel. I average about 35mpg and get around 40mpg+ on the motorway

      about 25 days ago
    • Qmentis
      Qmentis

      AKA VW the mpg scammers, designing the engine to meet the test then in the real world its horrible.

      about 25 days ago
    • Qmentis
      Qmentis In reply to Qmentis

      @Kneek Knocks The legal class action against VW in the UK is for that and fuel economy because once then engine is "fixed" the and power mpg drops... i believe ford have the same issue on rangers.

      about 24 days ago
    • Kneek Knocks
      Kneek Knocks In reply to Qmentis

      Qmentis for NOx emissions and co2, not fuel economy.

      about 24 days ago
    • gmcjetpilot
      gmcjetpilot

      I have a turbocharged 2-liter TDI Diesel and it gets almost 50 miles to the gallon on the highway.

      about 26 days ago
    • gmcjetpilot
      gmcjetpilot In reply to gmcjetpilot

      @Paul Kojack yeah I know.

      about 23 days ago
    • Paul Kojack
      Paul Kojack In reply to gmcjetpilot

      Different with a diesel. Basically all diesels have turbo's because they have alot of advantages for diesels, they run much better the more pressure you can shove into the cylinder. Old non-turbo diesels were real turds in alot of ways.

      about 24 days ago
    • TheD
      TheD

      Turbo läuft, Turbo säuft

      about 26 days ago
    • Brian Heard
      Brian Heard

      You're talking about spark ignition turbo engines. Take a look at compression ignition turbo engines. Different story.

      about 27 days ago
    • D R
      D R

      My wife's 2015 C300 (2.0L Turbo ~270hp) gets EPA numbers; about 33mpg mixed, 39 hwy.

      about 27 days ago
    • Oddreign Odd
      Oddreign Odd

      I don't expect 40 MPG on my turbocharged 4c vehicle whenever I floor the gas pedal. At that moment my only concern is to get to where I want faster.

      about 29 days ago
    • DavixDevelop
      DavixDevelop

      I prime example of this is the BMW 118I (E87), which has a 2.0 engine and the BMW 116I (E87) with a 1.6 engine.

      about 29 days ago
    • Tyler
      Tyler

      In other words, don't drive aggressively. Just drive normal, you can still have fun. I drive fuel efficiently in my 2019 Civic Hatchback Sport Touring w/ a 1.5T CVT, I get 36.5-38 mpg.

      about 1 month ago
    • Turd McGurk
      Turd McGurk

      So basically, if you drive more aggressive, you get worse mileage. Doesn't this apply to all motors? My wife's 2018 Civic has an average of 40.3 mpg on the dash right now. The appeal is that she can get 40 mpg but it also doesn't fall on its face when merging on the interstate. I think you lost the point in these small turbo motors.

      about 1 month ago
    • travis dunn
      travis dunn

      Because 1. TNSTAAFL
      and 2. Any system designed for variant operating conditions will always be less efficient in a specific condition than a system designed for only one condition.

      about 1 month ago
    • Scott Aubel
      Scott Aubel

      The reason my 10th gen civic si doesn’t get good milage because I can’t stay out of the boost. On the highway it gets 38 and around town I get 27.

      about 1 month ago
    • Ley enda
      Ley enda

      Don’t run your car a boost all the time

      about 1 month ago
    • Kent Hammersvik
      Kent Hammersvik

      Knock in small or big turbocharged engines is not a problem. If knock is happening it is because of low quality/octane gasoline. ALL of Europe has Octane 95 as standard. The USA needs to leave the past behind and start using Octane 95 gasoline.

      about 1 month ago
    • Kent Hammersvik
      Kent Hammersvik In reply to Kent Hammersvik

      @Lynn - what do you mean by different system? Octane gasoline is the same all over the world.

      about 1 month ago
    • Lynn -
      Lynn - In reply to Kent Hammersvik

      They use a different system, its the same octane converted.

      about 1 month ago
    • Kevin B
      Kevin B

      I used to drive the "turboed" vehicles back in the 80's (yes, I'm old), and it was the same deal back then -- you had to stand on the gas to get any power. Seems not much has changed since then.

      about 1 month ago
    • Ismaïl Aarabe
      Ismaïl Aarabe

      What about the intercooler???

      about 1 month ago