Civic grill block, front undertray, tire deflectors

[daqcivic]

I've been lurking here on ecomodder for several months now, reading up on HFE driving techniques and aero mods, I'll begin with a brief introduction: I started hypermiling about a year ago when I was delivering pizzas, and got myself up to about 43 MPG combined driving slow and coasting. Since then I switched jobs, logging most of my miles on a 10-mile city commute. I've been getting about 39 MPG with 80-85% city miles, mostly in heavier traffic. I'm still trying to learn how to tweak P&G for my car and driving conditions, but that's another subforum. However, once or twice a month I make a 240-mile round trip on I-5 during off hours, which is perfect for working on hwy FE and aero mods.

My 1st mod, which I don't have pictures of, was installing some front tire deflectors like those seen on most new cars--just a flat piece of plastic placed to cover the inner half of the tire profile and a few inches inboard of that. Based on observation and reading, it seems that this is usually the optimum placement as much of the drag in this area comes from the wheel wells and their interaction with the inner sides of the spinning tires. I didn't get any solid comparison testing with this mod.

My 2nd mod was a grille block:


The radiator is tiny, and covers only the passenger side of the grill opening, so the grill block leaves about 30% exposed. I have not measured any significant improvement with this, which is frustrating and confusing, especially since the whole driver's half of the grill was just letting air straight into the engine bay where it slowed down and exited underneath. I know my temps are fine and the fan almost never comes on. Eventually I will optimize this mod by moving the opening to the center of the radiator area and sealing the zone between the grill opening and the radiator face.

My 3rd mod was an front undertray made of coroplast:



The stock front underbody was very uneven, but I finally managed to get a smooth shape and screw it down. I haven't really tested this mod on its own, but in my judgment the airflow will have to be smoothed farther back and the engine bay venting will have to be optimized in order for this mod to reap any overall drag reduction benefits.


I've recently tweaked the undertray, adding some coverage to the wheel wells and adding pieces further back:



I'm not really happy with how it turned out, as there is just too much void aft of the front undertray piece, especially in the middle exhaust tunnel. I was going conservative because I wanted to make sure there was enough opening to extract the air going through the radiator. I've actually already got a coroplast piece measured and cut for replacing the section from the front wheels to the rear of the engine bay, but I didn't have enough time to install it.

Along with the undertray revision I made these larger curved front tire deflectors:



Sorry for the blurry pics, daylight was gone. I need to reshape these to cover more of the wheel well opening, and to extend the aft edge farther back closer to the front tire.


Up next will be the revised tire deflectors, extended undertray, and rear undertray.

So, comments, suggestions, comparisons?

[Arminius]

Nice clean work! I'm envious.

[cfg83]

daqcivic -

Wow (understated because very impressed).

CarloSW2

[daqcivic]

Thanks, I'm hoping to steadily improve and expand the aero mods.

[FastPlastic]

Looks like your off to a good start

[lunarhighway]

good work...i wish my undertray would extend that far back.

your wheel dams remind me of mine, although i think yours could be bigger,

in observing wheeldams and airdams on production cars, ive noticed a pattern that sugest a fair deal of the dams are aimed at divirting air away from the inner wheel well rather than the tire surface (wich in itself isn't a bad thing)

i initially extended my inner wheel well liners to form a vertical dam that curved inwards

you might want to test this feature on your dam. i got a piece of linoleum on discount to make the dams, but i had so much leftover i stated looking at other applications and basically used it to make dams like you have that would cover most of the initial vertical dams.

i think your dams might be improved upon by making them go straight down at the outside and also much wider on the inside so they cover the inner wheel well more and gently blend with the existing tray.

if you look at your original bumper you notice the outside is a little lower than the inside, so perhaps you could use these dimentions as an indication of where the manifacturer wanted the air to ga and enhance is with a fairing. like this for example



here's what i've made so far although it's still needs improvement

[vtec-e]

Top notch work. Well done. Have you done any mpg testing?

ollie

[daqcivic]

Originally Posted by lunarhighway

in observing wheeldams and airdams on production cars, ive noticed a pattern that sugest a fair deal of the dams are aimed at divirting air away from the inner wheel well rather than the tire surface...

i think your dams might be improved upon by making them go straight down at the outside and also much wider on the inside so they cover the inner wheel well more and gently blend with the existing tray.

Good analysis; this is precisely what I have observed and planned for my next iteration.

Originally Posted by lunarhighway

here's what i've made so far although it's still needs improvement

Yours are pretty much what I'm going for. I had never thought of using linoleum. I used plastic plant buckets since they retain a curve when cut. I just need to get a bigger size next time to extent further down and inward.

Thanks for the feedback!

[daqcivic]

Originally Posted by vtec-e

Top notch work. Well done. Have you done any mpg testing?

I've had difficulty finding the time and consistent conditions needed for accurate testing. I need to find a place to do coast down. Since I have no instantaneous FE instrumentation, and I live in Oregon (so I can't pump my own gas), I really need repeated long hwy trips to factor out uncontrolled variables.

I'm not much of a scientist/engineer. I tend to get fixated on ideas and rely too much on intuition—at least too much to prove anything with certainty. But hey, I was a humanities major, I was only taught to deconstruct objective claims .

However, I still need to do enough testing to at least convince myself it's working, so I do plan on doing some more dedicated testing.

[Daox]

Very nice.