Quote:
Originally Posted by stevej37
Same as the Infiniti system in the OP
How could valve timing vary the compression ratio?
|
No, it is not the same. Porsche one is a 2 position, Inifiniti is an analog adjustment.
You could also vary the height of the cylinder head which is how a CFR engine works (that is the engine used as the standard test for octane rating).
Valve timing- late closing of the intake valve aka Miller Cycle. You push some of the fresh air back out and this gives you a longer expansion ratio than the effective compression ratio, at the cost of some displacement.
I have no idea how the extra complexity and mass gives a big enough thermodynamic benefit over the Miller Cycle to justify itself.
Personally, I find this more interesting.
http://www.thedetroitbureau.com/2017/01/mazda-aiming-to-first-with-breakthrough-hcci-engine/
__________________
1971 911S, 2.7RS spec MFI engine, suspension mods, lightened
Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance
Last edited by Flieger; 02-04-2017 at 07:50 PM..
|