Atkinson cycle valve timing v compression ratio?
Atkinson cycle valve timing v compression ratio?
(OP)
I would like to build a SB Chevy engine to run as an Atkinson cycle engine. By Atkinson cycle I am referring to high compression with late intake valve closing. Pump premium gas. I am willing to live with reduced power output for a slight increase in efficiency. Can anyone provide a starting point for compression ratio v intake valve closing point? Advertised or @ 0.050" lift. I can taylor the ignition timing for RPM and MAP but I need to stay out of the CI range. Thanks for the help.





RE: Atkinson cycle valve timing v compression ratio?
RE: Atkinson cycle valve timing v compression ratio?
I have seen it called both. I am not ready for a blower yet thus my choice of terminology. Also Ford and Toyota seem to like the Atkinson term. I am not sure why. I have not been able to find cam timing specs on the Escape Hybrid and the Prius specs that I found did not give the lift that they were measured at. I did a search here on Miller and did find some helpful info. Thanks Ken
RE: Atkinson cycle valve timing v compression ratio?
RE: Atkinson cycle valve timing v compression ratio?
The Prius uses a modified Otto cycle, with a conventional crank and conrod. The valve timing is adjusted to produce an Atkinson/Miller type of expansion, and the crank is offset. But there are no rocker levers or a secondary con rod.
It's interesting to see how people keep mentioning that animation in the context of the Prius.
http:
has a reasonably accurate description.
The following document includes a cross section through the engine on p14. It could be that Toyota is telling fairy tales. I doubt it.
http://www
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Atkinson cycle valve timing v compression ratio?