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DIY flat underbody

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Old 04-14-2019, 03:55 AM
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Default DIY flat underbody

I've recently been very interested in aero and making my car faster on the track without having add horsepower and make my engine unreliable. Here's my progress so far.







Eric
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Old 04-15-2019, 04:24 AM
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Keep us posted with your testing and data. Always been curious how effective flat under body panels could be with our cars.
Old 04-15-2019, 04:51 AM
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they are highly effective, it is important to make sure the trans and diff have either coolers or adequate airflow to keep them cool
Old 04-15-2019, 08:55 AM
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Is that alumalite? Did you just heat it to bend it up for the front wheel spats?

Interesting approach to mounting the center section. I'm trying to see if there's a way to use rubber wellnuts to mount it to the existing holes in the bottom of the frame rails. Any issues with exhaust clearance?
Old 04-15-2019, 11:56 AM
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Looks good, Eric.
Old 04-15-2019, 11:58 AM
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Observations:
  • No front diffusers
  • A long skinny panel with no management of air from the sides, vortices off of the tires.
  • No ducting around the radiator
A few years ago a Ferrari flipped in the 12 Hours of Sebring giving a good view of its underside:



Note the complete seal, front diffusers, coverage under the suspension, and vortex generators around the wheels.

If Flow Vis would work on the underside, it may show you what is happening. Messy though and if the flow is turbulent may not show anything meaningful.
Old 04-15-2019, 06:48 PM
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Thanks everyone for your input.

This is in the beginning phase, I have plans for front diffusers, along with cooling ducts.

How important do you guys think it's to have an air inlet for the trans and diff? I was thinking the diff but hadn't thought much about the trans.

Yes it is some form of alumalite but does not have large corrigated holes , it's more dense between the aluminum. 6mm thick sign material.

I just bent the ends of the splitter up with my hands ,feet and some blocks of wood and a hammer. I still need to trim the splitter some.

Right now I'm about 2in lower then my exhaust. One thing I'm unsure of is how the hot exhaust will damage the alumilite or if it will be able to disperse the heat. I plan to raise the undershield up for more ground clearance and possibly heat wrap sections of the exhaust that might touch.

I plan to do my first track day in over a year on may 10th at CMP with scca track night. Looking forward to getting back on the track.

Thanks Eric

I just slowly bent
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Old 04-16-2019, 05:02 AM
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I would absolutely include some kind of opening or duct for the transmission. You can buy NACA ducts that will fit in that area and should be relatively simple to just cut the hole for and install.
Old 04-16-2019, 05:14 AM
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100% need trans cooling. stock my trans tunnel gets flaming hot after 20min on track. cuting off all the cooling i wouldnt even want to know how bad it would be

as someone else started i would highly recommend some splitter diffusers, make sure the flat bottom connects with the rear diffuser with a gentle curve vs a butted joint from flat to angled this will aid in air flow attachment, if the air detaches it negates the benefits of the diffuser. side skirts should extend out past the body to stop air from the top side "spilling over" under the car. additionally the diffuser behind the tires could be removed and sealed off with the diffused portion only in the center. there should be vertical walls to channel the diffused air and not allow it to spill over behind the tire. picture attached for reference
Old 04-24-2019, 03:28 PM
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you can take some ques from Passwords design.

Honda S2000 Diffuser - Honda Tuning Magazine


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