Quote:
Originally Posted by JulianEdgar
There is possibly a way of doing this with electronic throttle.
- You will need two people, flat and straight road, decent speed update OBD data.
- Drive car at constant speed eg 100 km/h. You will probably be able to do that more accurately than the cruise control, but see which is better.
- Passenger reads actual throttle blade position (or total engine load if such a figure is available).
- Figure needs to stabilise eg less than 1 per cent variation as you hold speed constant.
- Repeat test and make sure figures are very close.
- Open all windows. Go back over same stretch of road with all windows open.
- Maintain same speed.
- Read what actual throttle blade position (or total load number) now is.
If the blade opening or load number has distinctly increased, then you have a base reading for what causes a major (eg typically 12 per cent) change in drag.
If that is the case, you have a go / no go indicator for aero mods - so long as the change with the aero modification is above the variation in the readings at a constant speed.
However, do not apply any maths to attempt to work out percentage changes - too hard when throttle blade position / load number is probably not linear with power (or torque).
(And I wouldn't do it with the Prius yet, in case electric power is also changing.)
Let us know how you go! |
The obdfusion app does have engine load and engine torque output options, it also has a performance option that measures that is similar to drag racing timing system but uses actual data from the obd port. I will experiment with engine load parameters and see what happens. Thanks for the idea.