Real World Test

It came as an afterthought.  It was never my direct intention to have done what I made.  I had initially made a Secondary Intake for reducing fuel consumption of this car.   See my previous article.  Then I wanted to make the spoiler adjustable so that it can actually be useful.  This was on my previous thinking that the spoiler functioned as perceived.  That it provided down force and that if I took it out, the handling would suffer.

This then changed somehow without any premeditated intentions.  What I have right now is a combination of efficiency solutions.  The secondary intake initially showed that I could save money in the movement of the throttle.  That was fine.  Then the aerodynamics were sorted.  Never did I thought the two combined mods made significant fuel saving changes.

I did a test run yesterday for 230km in total.  This was a return trip on the North South Highway.  It was to test the Deflector at speeds above 90km/h.  It performed admirably by registering an Indicated average Fuel Consumption (FC) of less than 5.0 l/100km. You can see the YouTube video here . Yes, this means I now have a YouTube account.  Forgive me I am rather slow at 46 years old.  I have only now found the use for it.

During the same journey I made similar tests for speeds of 100, 120 and inadvertently 130km/h.  All of these test results were on solid straight roads with the AC switched on.  I plotted the values which I had observed on a spreadsheet.  I had expected a exponential curve from 100 to 130km/h.  But I could not get it.  The only time I observed a high FC is when the car was being driven at 100km/h up a 20 degree incline.

capture_11092014_004322The table is now UPDATED on 9 November 2014.

The data is based on observed data from factory standard equipment.  They are not absolute and the value is AVERAGE Fuel Consumption.  The last data if drawn to scale should be closer but it should also be higher.

A few things floated in my mind.  As engineers we are told that aerodynamic load is very much affected by speed of the object or vehicle.  This aerodynamic load increases .  Fuel consumption will increase dramatically as speed increases.  Perhaps it is too early and too easy to say that somehow with the combination of both modification, we have come to a point where the world is no longer flat.  I might need to spend more day trips to Melaka to do more tests.  One might say that these values at these speeds are insignificant as the speeds are low.  But these speeds are what normal people are driving at.  This is the whole point of doing these modifications.  It is so normal people could save money driving normally.

Should anyone ask about performance degradation; I simply did not see any.  The maximum top speed is still attainable.

Adjustable Spoilers Part 5

A day after posting Part 4.  I did a calculation using a spreadsheet.  I could either stick to my existing HITEC or get a slightly bigger one.  There’s a local Arduino reseller that has lots of TowerPro MG945 which has a stall torque rating of 12kg/cm at 6VDC.  I am definitely going to buy this.  Although the gears are of metal, due to the power that’s required, I prefer Nylon to take in the additional service demand.   I would also need to reduce the surface area by 30% while limiting the angle to not more than 30º.  As preparation to accept this servo I had to install a 3 wire cable taken from a power cord extension.  The length is about 1.3m which is sufficiently long to have the new controller next to the mid console close to the handbrake.  I have routed this through holes that were meant for the rear water jet for the wiper and through one for the spoiler mounting.  It’s a bit harder than just that, as I had to remove two panels and I had to make sure the cable was not interfering with the rear seat belt mechanism.

Cable Routing for Servo

While at the same time, I found the bracket for the reverse sensor a bit too big for my liking.  I therefore made holes to shave off 20g.  It was not planned.  Since it was hard to remove these panels, I would not be seeing it for many years to come.

Reverse Sensor BracketA few more days and I finished my mechanical build of the spoiler and had it fitted on the car yesterday 27 May 2014.  I had a spin in it around Putrajaya, in the most decent of 80km/h speed.  It did not fell off even though all of the wooden part was held in place by nothing more than Dunlop Contact Adhesive and two screws.  I had another spin today at much more livelier speed around the same track and it is still there on the roof.  I might add more screws to keep it all sane.  I used normal green coloured Garden Wire to secure the angle of attack.  I do not want the angle to be too big that it would add drag and load onto the new assembly.

Rev1 Front 3/4 view

New Wing

Rev1 Rear 3/4 view

I am happy to report that on the first test, I recorded an 18% fuel consumption reduction.  Initially the average at 80km/h is 5.3l/100km.  Now it is 4.3l/100km.  Tell me again how much that hybrid costs!  This is amazing.  Previously I could only make 4.0l/100km on a flat straight road.  But with this spoiler. I could drive it normally without having to use hyper-milling techniques to get close to that.  It goes to show that it does make sense to make the air separation as late as possible.  The angle of the spoiler closely matches the angle of the hatch.  I cannot be too sure if I had also reduced the wake.

With that I have completed the mechanical build and managed to clean the wet kitchen area of my house clear from tools and debris.  This gives much joy to my wife.  The next steps will be to finalize the electronics.