×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

long stroke efficiency

long stroke efficiency

long stroke efficiency

(OP)
I have a question about the theoretical maximum stroke length of an engine and the resultant efficiency.  With direct injection it is possible to keep the intake valve open during part of the compression cycle.  In theory then, we could take an engine with a 10cm stroke length and 10:1 compression and double the length of the cylinder yet keep the 10:1 compression ratio.  Then during the power stroke the piston would move 20 cm and make more efficient use of the available energy.  Of course, a cylinder could be made too long and after the piston has traveled so far no more energy/pressure is available to move the piston and friction would begin to reduce efficiency.  So my question is, how long in theory can a cylinder be made to make use of all available energy and by how much would this increase efficiency over today's engines?  Thanks for any help -- I'm new to this forum.     

RE: long stroke efficiency

That's an Atkinson cycle. You need to model the frictional behaviour of the piston and bearings to see the tradeoff.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources