3 options to resolve mpg drop after front air dam install?

[2000mc]

is there a lower grill or other opening on the underside of bumper?

[oldtamiyaphile]

Originally Posted by beluga

I'm ALSO sad that my mpg increase from various mods is only helping me 8% or so vs a lot of 30-40+% increases in MPG I see from many other people here... not sure what I'm doing wrong.

The big gains are not from mods, they're from driving style. Most people (some extreme cars excluded) will probably see 30% from driving and 10% from mild mods. Both my signature cars are stock (even tyre pressures!), but still doing reasonably well.

[serialk11r]

Yep, driving style is most of it. Consider this: one of the threads in the aerodynamics section had a link to some stuff suggesting that smooth wheel covers decrease the drag of the wheels by 15-20%. The wheels account for maybe 25% of the drag of the whole car. Drag accounts for maybe half the total fuel consumption of the car (where engine inefficiency is considered "consumption"). So adding smooth wheel covers gets you 2% more fuel economy if you're lucky.

That's a similar change in magnitude to substantially lowering the car, adding a belly pan, adding grille blocks, etc. So if you do the whole suite of simple add-on aero mods you'll get maybe like 10% more mpg if you're really lucky. By comparison pulse and glide can give you a 20% boost easily.

I never really noticed the gas needle moving any slower when I lowered my car, added a grill block, pumped up the tires, or used thinner oil, but the gas needle definitely moves down a lot faster if I cruise at 65 vs. 60 or 55, and it definitely moves faster if I get lazy and don't pulse and glide. That means with aeromods you have to 1. not expect much and 2. know that measurements of the effects is very difficult.

[MetroMPG]

Yes, and yes.

When I A-B tested a "suite" of aero mods together on the 2014 Mitsu Mirage:

- air dam
- medium kamm back extension
- grille blocks
- 1 wiper arm delete
- passenger outside mirror replacement
- driver's mirror folded back

With all those taken together, I only saw a 4.5% improvement in fuel economy at 90 km/h / 56 mph.

http://ecomodder.com/forum/showthrea...ini-29182.html

That's why I'd be very reluctant to try reading the tea leaves on any single mod from tank-to-tank testing. A gain or loss will be hidden by normal variability.

[beluga]

Originally Posted by 2000mc

is there a lower grill or other opening on the underside of bumper?

now that you ask. why yes there is, i hadn't noticed before.

do you think that not blocking it is compounding the airdam mpg drop? I do drive plenty of extreme P&G most of the time, except for the occasional instance of running behind and therefore doing 65-75 half of those times..

[2000mc]

I'd still be in the camp of people thinking the air dam likely isn't hurting, more likely tank to tank differences.
I would definitely be closing up that gap myself, and of course keep a close eye on your temps when you do it.
I think that opening would at least partially neuter the gains of the air dam, by causing some additional air to flow through that opening

[California98Civic]

An airdam of your design should help. I agree with the comments above: better testing needed. And yes, driving style is my single biggest variable. Something else you might also try is always fuel at the same pump at the same station using the same method: slowest fill rate, stopping at the first click. This minimizes what can be very significant data-noise from pumping variations.

[Whitetail Ranger]

I just took off my extra air dam i made off my truck to see if it has created too much frontal area on my truck..The bigger one thats actualy attached to my bumper i left on though..If you look at the pic of my truck you will see what i mean by having 2 air dams.

[aerohead]

*The only way meaningful results are going to emerge from the signal-to-noise ratio is to:
*Fully-warm the vehicle with at least 22-miles of continuous 50-mph driving.
*Immediately top-off the tank,to the brim.
*Get right onto a highway.
*Get up to a constant velocity and hold that velocity constant.
*Drive a meaningful distance (an entire tank would give the best accuracy)
*Decelerate,do a U-turn.
*Accelerate back up to your prior velocity.
*Cruise at that velocity,back to your origin.
*Drive directly to the same gas pump and top-off.
*Your comparison mpg baseline must be developed in exactly the same fashion,or else you don't HAVE a baseline with which to compare.
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*You cannot drive in urban traffic
*No stops
*No yields
*No idling
*You cannot pulse and glide
*The weather needs to be the same as without the mod
*You must drive the identical route
*The only variable allowed is the single modification.
*Natural mpg variability could be around 12% depending on weather,grades,road surface,curves,traffic,etc..
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Wind tunnels were developed to simplify data extraction.Everything can be accounted for.Road testing is fraught with hundreds of pitfalls.

[ME_Andy]

I'd trim away the middle section if you don't see better mpg's over another tank or so. Looks too low to me