Quote:
Originally Posted by Daox
I'd recommend reading this:
Autospeed - BFSC
It'll introduce you to brake specific fuel consumption. More throttle while cruising is a good thing. Its why I have been able to get 70 mpg out of my paseo. |
Excelent article - thanks for that....
So to sum up what I understod from that read was:
- best mpg at peak tourqe - hence the graphs (nothing new there)
- Dosen't work on diesels as they don't have any throttle (Nothing new here)
- Pump losses / restiction in the intake path of the engine caused by the throttle valve is the main culprit here....
So - what the WAI / HAI does, in providing hotter air to the engine is actually lowering it's effency at lower rpm, so that one has to apply more throttle to achive the same speed / rpm, thus lowering the resistance in the intake system because throttle valve is now in a more open position.....
OK - if we accept that pumplosses / restriction at the throttle valve is the culprit this actually makes sence.
So what we are looking for - is trying to optimise towards is a fully open throttle valve (= lowest restriction) at low rpm's.
We are also looking for lowering the rpm number where peak tourque occurs.
In connection to the last, it should be possible to optimise the intake for best tourque at lowest possible rpms.
One way to do this is to change the lenght of the intake tube. This is the distance from the airbox the the mouth of the tube.
This is engine specific, and depends on the pulse in the intake system. Some engines might like at shorter intake tube, while others might benefit from a longer one.
Even small changes can make a difference. Also the intake tube mouth should be bell shaped to improve airflow and lessen restriction.
Usually Toyota are good at this, while for instance the Peugeot 106, 206, 306 were terrible, and could be optimised a great deal.
Lots of room for new experiments here
