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Old 03-03-2012, 07:58 PM   #1 (permalink)
EcoModding Apprentice
Join Date: Jan 2012
Location: Cambridge, UK
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Airdam - suprise result!

My little 3 spd automatic Daihatsu clone (Perodua Kelisa) badly needs some help in reducing FC.

I've already fitted new Michelin Energy E3B tyres - one size up and inflated to 40psi.
I have a grill block - which certainly speeds warm-up (3 minutes!)

But I suspect that it is about as aerodynamic as a brick. I've mentioned elsewhere that on a cost-down test it would slow from 50mph to 40mph in 14 seconds - compared to 34 seconds in the case of my (much heavier) VW Golf Wagon...

Today I tried a simple air-dam using 5inch lawn-edging. It isn't ideal, as it is slightly too low (being below the lowest items under the car) and is also more flexible than I'd like. It is only 1mm thick plastic, and I am pretty sure it must tend to fold back under air pressure at speed. So I wasn't very hopeful as far as results are concerned.

But to my great suprise, when I did the cost-down test again, from 50 to 40 mph, instead of slowing in 14 seconds, it took nearly 20 seconds!!! (I repeated the test several times)

Now, it was just a quick and dirty test - with no account of wind (although the air did seem fairly still) but it does look like a very encouraging result.

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