ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Determining efficiency of a engine?2-stoke and 4-stoke!

Updated on September 28, 2011
Cylinder piston system
Cylinder piston system

It is easier to do than seems by the title. The efficiency of a engine means the efficiency of the engine thermodynamic cycle, which in turn means the efficiency to convert the heat supplied into work output. One thing should be made clear that the 2nd law of thermodynamics puts a constraint over 100% efficiency that is it is impossible to have a cycle that converts the entire heat into work output. It, however doesn't violate the energy conservation principle as some heat is rejected which balances Qin=Qout + W.

2-stoke diesel engine
2-stoke diesel engine

To determine the mechanical efficiency we need a machine or say device which we call indicator engine(see pic 2). Lets get acquainted with what it is....At the first sight it might look damn complicated but we are interested in few of its things. The very first is the cylinder piston engine (see left part of image) which performs the same cycle that is performed by the engine we are interested in.The other parts include the wheel and the drum on which a pencil connected to piston draws the indicator diagram. Now lets see how to know the efficiency, For that we first of all find the area of the indicator diagram (ad) using Planimeter . And the diameter of the wheel (ld) is measured. Knowing the spring constant ( K) of the spring attached to the cylinder-piston, we find the Mean Effective Pressure (Pm)

Pm= ad * ld / K.

Now we calculate the work done in terms of Pm. Then we have the work output in a cycle.

Before moving further lets see what 2-stroke and 4stroke engine are. The engine which completes its one cycle in 1 complete revolution of the wheel (or stroke) is termed as 2 stroke engine. And the one which takes 2 complete revolutions are 4-stroke engine.

Now if 'N' is the number of revolutions per minute of the wheel (rpm) and there are 'n' cylinders. Then the indicated power for 2-stroke is given by

I.P.= Pm* A * ld * N * n/60. The unit is in watt

for 4-stroke -

I.P.= Pm* A * ld * N * n/120.

Now we find the shaft power; the power made available for rotating the wheel.If 'T' is the Torque transmitted. Then Brake Power for 2-stroke is given by-

B.P= T * N *24 / 60

And for 4-stroke -

B.P= T * N *24 /120.

Now we can have the mechanical efficiency which is nothing but the ratio of brake power to indicated power.

It should be noted that mechanical efficiency can be increased by reducing the dissipative forces and ideally can be 100%.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)