View Single Post
Old 02-06-2013, 05:06 AM   #27 (permalink)
renault_megane_dci
Master EcoModder
 
Join Date: Feb 2009
Location: France - Paris
Posts: 762

la_voiture_de_courses - '03 Renault Megane Estate
OldContinents
90 day: 44.34 mpg (US)

xiao lan - '01 Audi A2
90 day: 38.88 mpg (US)

Brit iron - '92 Mini Mini
90 day: 45.5 mpg (US)

Prius - '09 Toyota PRIUS Lounge
90 day: 47.37 mpg (US)

Beemer - '06 BMW F800 ST
90 day: 53.06 mpg (US)
Thanks: 188
Thanked 33 Times in 30 Posts
It is interesting to figure out what is happening at various engine speed.

The Atkinson cycle aims to maximise expansion to compression ratio.
If I understand it right, at lower throttle openings, the cylinder is already not filled up to its max because of the throttle.
At this opening, there is not gonna be a great deal of reversion because there is a throttle plate in the way and the balance between cylinder and inlet pipe is not that great.
It is also not a spot in the rpm range where Atkinson cycle is gonna improve much on Otto since most of your loss is pumping loss from the throttle plate.

When you hit peak torque, the story changes, there is air flowing backwards.
Now, what about we tune the inlet length (from valve to throttle plate) to have a spare volume fairly higher to what is gonna be dumped out of the cylinder ?

The air might have a tendency to compress before it goes back being refuelled again.

With a longer inlet we could have more "stop and go" pulses but without any issue carb wise ...

Let's not forget we want to increase static compression ratio to match the previous dynamic compression ratio to get the most out of this mod.
  Reply With Quote