Aerodynamic Belly Pan on Toyota Echo

[jimepting]

I have spent a fair amount of time lying on my track mat underneath my Echo trying to figure where the most productive underbelly additions could be made. The areas in front of the rear axel are pretty clean, particularly in the mid-car area. In addition, Toyota added a small flow smoother behind the front bumper. The area behind the rear axel is a real disaster. It has lots of rough protrusions and lots of “vertical” wall sections in front of rear bumper - pretty typical on many cars. (See the first three pictures which reflect these problems.)

Spending still more time on my back, I quickly concluded that though a rear belly pan would be helpful, there was no way to attach one. So I set about designing and constructing a light framework using small aluminum channel and angle, purchased at Lowes. I also had to add some attachment points for the framework. (The fourth picture shows this framework.) The lower bumper cover was planned as the rear attachment point for belly pan .

With the framework in place, it only remained to cut the coroplast in two pieces, one large, one smaller, and to attach the coroplast to the framework with self tapping screws. Note the section of aluminum flashing which was used in the area of the exhaust pipe. Also note that the muffler is left uncovered to maintain cooling.

I plan to do some ScanGauge testing when I can return to my baseline test track in a couple of months. Obviously, I won’t be able to do the more desirable A-B-A type test, but my previous baseline should support some rough conclusions

[Ferr3t]

Awesome work Jimepting! Although I'm curious as to why you didn't start from the front and work your way back? Regardless...this should help with some of the flow under the car .

[winkosmosis]

Looks nice, good job avoiding the muffler.

Ferr3t, I think he did the back first because the parachute rear bumper was the most offensive

[cfg83]

jimepting -

Wow, that was worth the wait! Very clean execution.

CarloSW2

[lunarhighway]

nice job indeed, i've been thinking about something similar, so it's nice to see how you made the braces.

the only thing that has been keeping me back, and i don't mean to discourage you, is the report that rear undertrays are far less effective when the underside ahead of them is't smooth... of course any improvement no matter how small is worth it. and i hope you see a nice improvement.

[jimepting]

Originally Posted by Ferr3t

Awesome work Jimepting! Although I'm curious as to why you didn't start from the front and work your way back? Regardless...this should help with some of the flow under the car .

Toyota did some under belly work at the front, immediately behind the front bumper. Though there are a couple of areas which can still be enclosed, the front didn't look nearly as rewarding as the back. I will probably do some additional front work when I get the chance.

The front, around the engine, would seem to have some additional constraints. It would seem that the exhaust system would need to be left open, and some airflow out of the radiator area must be maintained.

Sorry, I don't have pictures of front area. We are traveling in the southwest and my ramps (concrete blocks and boards) are stashed in a weed patch in TN - no not that kind of weed

[NeilBlanchard]

Hi,

I can tell that the Echo and the xA are very similar:



I had to take it off for the winter -- too much stuff would have gotten stuck up on top. Do you have pictures of the front grill area? I have found that sealing up and smoothing the nose of the car is at least 2X more effective than mods on any of the other areas of the aerodynamics.

Scion xA aero mods

I tried covering the holes in the radiator cowling, between the bumper and the radiator, and I found that it added drag -- though I think if you close down the front grills enough, you can see some big improvements. (See the latest grill block at the end of the thread.)

I think the Echo has one big advantage over the xA: the wheel openings are much tighter to the tires, I think.

[jimepting]

Very interesting Neil. I do plan to do some work up front. Looking at your photos, I am wondering if you attached the belly pan directly to the axel. I was tempted to do that, but of course the axel moves with suspension travel, so I thought it risky.

I have a very smooth grill block for the upper radiator grill. I find that the Echo gets plenty of air just through the bottom grill. I also block half the bottom grill in the winter. I have yet to test any of these mods, since it is winter and I'm away from my "test track."

I tested my fender skirts and found them worth .7-.8 MPG, near as I could tell. Small improvements add up, but they are tough to measure individually.

[MetroMPG]

Rear pan looks good! Thanks for posting the pics.

Originally Posted by jimepting

I plan to do some ScanGauge testing when I can return to my baseline test track in a couple of months. Obviously, I won’t be able to do the more desirable A-B-A type test, but my previous baseline should support some rough conclusions

Keep in mind that all else being equal, even an ambient temperature difference can have a measurable impact on fuel consumption. Something to keep in mind when drawing conclusions about something like a partial undertray that will likely have a small (but still worthwhile!) effect on drag,

[SVOboy]

Looks good indeed,