dieseltaylor Posted March 8, 2009 Share Posted March 8, 2009 This is from Gizmag, and I am really impressed that it was Fiat who invented the common rail diesel and now have gone significantly better http://www.gizmag.com/fiat-releases-multiair-engine-technology--is-this-a-fundamental-breakthrough-in-internal-combustion-engine-design/11184/ Quite an interesting site. 0 Quote Link to comment Share on other sites More sharing options...
costard Posted March 10, 2009 Share Posted March 10, 2009 Nah, this is hype. The emissions are reduced by mixing the exhaust with air, giving a lower concentration of emissions (particulates, CO and NOx). The power increase is achieved by a power achieving cam shaft profile - which would point to a mechanical valve operating mechanism, not hydraulic. Perhaps the hydraulics are there to damp the spring rates, I didn't read much further into the article. Any mech engineers on the boards? 0 Quote Link to comment Share on other sites More sharing options...
Other Means Posted March 10, 2009 Share Posted March 10, 2009 The cam can be power optimised as the valve system is now hydraulic. Seems OK to me. 0 Quote Link to comment Share on other sites More sharing options...
costard Posted March 10, 2009 Share Posted March 10, 2009 Hmm. I took a look at the diagrams at the bottom of the page - the exhaust valves are still powered directly by the cam, the intake valves do their weird hydraulic thing. So that's how they get their "blip" in the profile (for the intake valves on the exhaust stroke) without running into trouble with friction loads on the cam. So the intake valves are controlled by two systems meshed to the hydraulics. An expensive and complicated method of gaining some efficiencies. Can you imagine trying to repair the thing? Will Fiat pull it off? 0 Quote Link to comment Share on other sites More sharing options...
Lars Posted March 10, 2009 Share Posted March 10, 2009 Seems a clever design for a more variable cam. Fundamental breakthrough? Quite a bit of hyperbole there, eh? 0 Quote Link to comment Share on other sites More sharing options...
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