Show me your airdams or bellypan + results!?

[Eddie25]

Originally Posted by cosmick

Why would you not do both? Most cars need both, you surely don't want the undertray angling up from the "axle" to the front bumper, that would generate lift, which is both drag and instability.

time constraints mostly. the car does currently have bit of a belly pan from a different vehicle. car is fairly smooth underneath from the fire wall onwards. I have to deflect a belly pan around the sump and im very limited for attachment points. also I have an very short bumper overhang from the front wheel making it hard to design proper wheel spats. I want the car to look stock I don't want to go overboard. I nice airdam so far for me sounds like the best and easiest option

[mixu-]

I made my first air dam on my hybrid Jazz (european version of Fit) today. Jazz already has a small rubbery air dam to begin with. It's about 5cm tall and has 15cm (6") ground clearance.

I pushed my luck a little bit and made an extension of 5cm out of black coroplast. I used duct tape and zip ties to install the coroplast over the existing air dam. The job turned out to be really easy and fast. I drilled a hole through both the coroplast and the rubber and used two zip ties and two washers per hole to keep things in place.

I didn't get a chance to try it yet but it looks good for the first prototype and seems sturdy enough. Will post results soon.

[mixu-]

Ok, so the first results are in for the Jazz air dam.

I did a highway trip of about 350 miles, filled up twice and averaged about 50mpg. (Possibly 51mpg because I filled "too much" on the last fill-up.) For reference my lifetime average before that has been 44mpg. That being said I don't have enough data (and no ABA yet) to say anything definitive. Realistic guess about the improvement would be about 5-8%.

The Jazz is rated at 51mpg highway by EU standards. I guess I'll need one more mod to make the rated figures. And I do pay a lot of attention to how I drive. I don't understand how car makers get away with their figures in EU. When it comes to adjusting my driving style, I don't see how I could improve mpg other than by slowing down. And I already drive pretty slow.

[Eddie25]

that's still I nice little difference! and pretty well executed considering you say its made from coroplast! it looks good. my car usually also comes with an airdam that would be easy to extend like yours. but I bought the car without that dam, quite common for them to get knocked off on some roads round here, so I have to make a whole one from scratch

[jedi_sol]

I chose the belly pan route. It has netted me a 3mpg increase

[Eddie25]

Originally Posted by jedi_sol

I chose the belly pan route. It has netted me a 3mpg increase

forgive me if I calculated wrong but based on your signature thats a 10% increase! not bad!!

[UltArc]

No calculations yet, but my thread has a few images of a couple of designs. Took my air dam of when I got the underbody set.

Feel free to pull images if you want, the thread doesn't seem to be very interesting to folks. http://ecomodder.com/forum/showthrea...s-23604-8.html

[jedi_sol]

Originally Posted by UltArc

the thread doesn't seem to be very interesting to folks. http://ecomodder.com/forum/showthrea...s-23604-8.html

I love your thread! I think the problem is that it's in the wrong forum. "Success stories" does not have a lot of traffic in it.

[UltArc]

Ah, good point. So long ago.../thread hijack

New thread hijack- Jedi, your rear end is looking good- talking about STi, not the french picture...lol

[mixu-]

Originally Posted by mixu-

Ok, so the first results are in for the Jazz air dam. ...That being said I don't have enough data (and no ABA yet) to say anything definitive. Realistic guess about the improvement would be about 5-8%.

OK, so now I have ABA results. Or actually more like ABBAC results. I was mostly focusing on testing a kamm style "spoiler", but figured I'd do one last run to check the effectiveness of the air dam at the end.

Variables:
- Used the cruise control set to 80km/h according to OBD2
- There was no traffic in front of me at any point
- There was one stop in the trip (to turn around and head back). On my first B-run I had to accelerate a bit faster than I would've liked, hence the increased fuel consumption.
- Engine had reached 80C+ before I started
- Ambient temp was 12C when I started and 11C after the last round-trip.
- I looked for forced regens. One occurred at the first test round, but those results are not included here. Hybrid battery level showed about 70% for the duration of tests.

My 12km round-trips:
A: Without kammback, with airdam: 1st: 4,2l/100km
2x B: With spoiler, with airdam: 1st: 4,3l/100km 2nd: 4,2l/100km
A: Without kammback, with airdam: 1st: 4,2l/100km
C: Without airdam and without kammback: 1st: 4,1l/10km

Soo, all my mods, airdam included were actually hurting my mileage. Great success

As for why the airdam was not helping is probably related to the fact that the Jazz has a quite smooth underbelly and a small factory installed air dam to begin with. Me making the dam bigger did not seem to help.