Extending the Decklid (Toyota Echo)

[ChazInMT]

Good Luck

[ChazInMT]

Application of Vortex Generators to a blunt body

Here's a paper that should help you to understand VG's better. i.e., they don't work. Also note page 8, in their workup, they talk about the "Rear Edge Radius" and it's effects. It is plain to see that the bigger it is, the better. So looking again at the Holden, you can see it has a Very small radius.



The Renault is bigger.



But your Echo takes the cake.



This is why I was saying, doesn't much matter what you do, Toyota has optimized the design pretty well. It is certainly no accident that the rear edge radius on you roof is comparatively massive. I figure it close to 1 meter.

[CigaR007]

So basically, there is nothing that can be done without resorting to drastic modifications such as a Kamm-tail or boat tail ? If so, I truly apologize for pushing the VGs and decklid extension and thank you guys for elaborating/explaining the science to me.

PS : my Echo does not have the spoiler pictured above.

[MTrenk]

CigaR007:
--> VG's work, but you need to be an engineer or have a lot of time and money to make them work properly unless you have a lucky guess.
--> The deck lid could work just fine, but this forum doesn't have much testing with it either, so the same applies.
--> The Kammback / full boat tail solutions are tried and true on this forum, but I still have to say that not much 'real' analysis has been done, but we all know it works for sure, to some extent based on real driving data.

A lot of people on here are very knowledgeable, but the first rule in problem solving is to never believe anything anyone tells you. Use your mind to think everything through to see if it makes sense. This is the path to becoming the best learner you can be!
You have eyes, you read the report by Mitsubishi, and you'll read the report posted by Chaz... only YOU can decide how to interpret the data. Use your brain!

[CigaR007]

Spring is here and it motivated me to start my next series of eco mods. I have been contemplating raising the entire decklid and slightly extending it. As you will see in the images below, I used a 1.5" styrofoam sheet as the desired height of the decklid and I followed the car's rear tapering using clay; as to follow the "designed" lines.

I need some help figuring out if this approach is viable. If so, how can I optimize the transition from the C-pillar to the new height of the decklid ? The decklid extension should be a few inches, still haven't decided on the final figure though.

What do you guys think ?

Thanks in advance !

[MetroMPG]

I can think of one example of a car with a raised deck lid add-on (from the factory) for better aero (downforce). I saw it on the Autospeed site a few years ago. I'll see if I can find a photo. It might show how they handled the C-pillar/side transitions.

[MetroMPG]

Here it is...

More pictures: AutoSpeed - Holden Commodore VL SS Group A "Walkinshaw"

[CigaR007]

Ah yes, I remember that photo. It seems that creating a parallel and tapered sidewall is the way to go. However, I did not find any mention regarding the height of the new deck lid.

Back to work I guess !

[Frank Lee]

Make sure it doesn't hit the back glass when open!

[CigaR007]

Indeed Frank Lee. That was one of my first thoughts !