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Old 04-14-2019, 07:29 PM   #29 (permalink)
Vman455's Avatar
Join Date: Feb 2012
Location: Champaign, IL
Posts: 1,606

Little Red - retired - '05 Honda Civic EX
90 day: 49.03 mpg (US)

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
90 day: 58.55 mpg (US)
Thanks: 174
Thanked 1,388 Times in 728 Posts
Now that this year's event has come and gone, time to turn my attention to next year. This year, this little car was the third most efficient non-plug-in overall, behind a 2000 Insight and 2010 VW Jetta 3-cylinder diesel; that's more efficient than every other Prius there except the one Prime, including two Gen 4s. I don't have any classes this summer, so I'll have a bit more time to mod while the weather is nice. The plan is:

1) Get an accurate curb weight (me + full tank of gas) on the car, at a truck scale or one of the local recycling places (we have two in town that I can potentially use)

2) Brainstorm any other weight reduction possibilities

3) Swap in the new suspension I've had sitting in my closet since last fall. They're Godspeed coilovers with 6 kg/mm front and 8 kg/mm rear springs and dampers, which will be more to my liking since the suspension is ridiculously soft for my tastes right now. I'll also be able to fine-tune the ride height; on the aftermarket Tein springs it's on now, the driver's side front sits ~10 mm lower than the passenger side for some reason. Overall it's pretty close to the optimal 0.75 body cover:tire height ratio Obidi says typically results in lowest wheel drag, so I won't be changing the ride height much.

4) More aerodynamic modifications:
-add front wheel air curtain ducts
-add front wheel strake fairings from the 2018 Ford C-Max hybrid (already ordered)
-aluminum underbody panels to replace the coroplast ones that grenaded themselves two summers ago. These will be bolted in, with a vent near the catalytic converter where the engine bay exhausts now.
-vent the rear wheel housings with convergent ducts to the rear bumper edge, and front wheel housings if I can figure out how to do that with what little real estate Toyota left there
-add hood vents
-add spoiler extension

5) Get a front photo from some distance and write a Python program to count the pixels and calculate an accurate maximum cross-sectional area, so that I can...

6) Do coast-down testing and correct for wind (good way to keep up on my physics over the summer) to calculate an accurate CD. My goal is to get under CD 0.20 with minimal extension.

I'll be attacking these in roughly that order after finals are over (week of May 13).

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