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Old 11-10-2020, 02:25 PM   #1 (permalink)
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Rough Conditions and Aero Mods?

Hey all, if this is a thread that doesnít need to be started feel free to remove.

Iíve recently got a 250,000+km 1997 Civic Si in decent shape which Iím currently working on. Having been a cyclist commuter for more than 3 years, Iím always thinking about aerodynamics (in fact, as I work on this car, my velomobile project is sitting on the back burner). I got my license this September (still only 19) and Iím already disappointed with the design and economy of the cars Iíve tried. I want something sleeker, and more efficient.

Iím here to ask for opinions/ideas about aero mods that wonít compromise my ability to get through the harsh conditions here. Namely, snow. About a foot of it here currently, and I swear itís just getting taller and taller. The ground clearance of Civic makes it hard enough already to get through, so I canít imagine how things like an air dam or front scoop would react. Maybe itíll work? Let me know any experiences/advice/opinions on this.

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Old 11-10-2020, 04:26 PM   #2 (permalink)
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A grill block might be a good thing -- keep the snow out of your radiator. As long as there's something behind it (the grill) there, little reason it would buckle under pressure.

Most people seem to use lawn edger for their air dam/skirt...it would just give way if it scraped on anything, like hard/deep snow, and then return to it's normal shape after. I suppose the cold might make it brittle enough to potentially break, but better that than tearing your front bumper off.

As to anything else...if you design/build it to take a beating. it will. If you make it out of papier-m‚chť, it's going to crumble at the first sneeze.

If you can get one, and the shape works, you can try bolting a trimmed-down bumper - from the same make and model - upside-down to your current bumper, to make a chin spoiler. It'll be just as tough, since it's the same material. All depends on the shape/design of the one on there.

Have fun!
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Old 11-10-2020, 05:24 PM   #3 (permalink)
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Thanks for the tips. A grille block is something I’ll definitely be doing. I’d like to use Coroplast to make a nice scoop of my own design, but the bumper idea is clever. The Aerocivic’s nose/dam/thing shape (a scoop) seems like it would easily dig down into a snow pile, so I’m considering a front nose with a bit more upward sweep, like that of a Mustang I prototype or a classic Daytona. Would this shape be less efficient?

Durability is a priority, and I’ll for sure be covering the engine right up. They salt the roads here recklessly and I want that out. Moon discs, wheel skirts, and an underbody panel are on my to-do list.
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Old 11-10-2020, 05:26 PM   #4 (permalink)
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Quote:
I got my license this September (still only 19) and I’m already disappointed with the design and economy of the cars I’ve tried. I want something sleeker, and more efficient.
Welcome. So say we all.

What you have here is a use case. The Ecomodder folk wisdom here doesn't necessarily apply to your situation. I would look to, say, the Gambler 500.

ecomodder.com/forum/showthread.php/eco-off-road-budget-destroying-prius-you-decide-38366

From Permalink #2 there:

jalopnik.com/this-lifted-prius-trolls-jeeps

There's no problem with a lot of air under the car +belly pan -airdam. The ideal is a central air jet with spats shrouding the wheels*. Conveyor belting is your best bet, but keep the fabrication simple, just drilling a hole in it is hard.



This suggestion has two pieces — a U-shaped metal bracket and a piece of belting with two angled cuts. Leave the short end open so the belting can deform with impacts.


*See Aerocivic

edit:
Quote:
so I’m considering a front nose with a bit more upward sweep, like that of a Mustang I prototype or a classic Daytona. Would this shape be less efficient?
The point (no pun!) is the stagnation point. It determines how much air goes over or under the vehicle. Or in the case of the Cybertruck, down the sides.

Here's an example of a metal clip that would grip conveyor belt by the edge:


http://wpc.ac62.edgecastcdn.net/00AC..._PROD01_lg.jpg
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Old 11-10-2020, 05:32 PM   #5 (permalink)
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2-door or 4-door?

Post some photos including a side profile and something explaining the front grille.

There is a sticky on grille-blocks, I forget if it's the top or bottom one you should try first.

Driving style has a lot to with mpg.

Front chin spoilers only really improve aerodynamics if they hang no lower than the dangley parts under the car.

I suspect your Honda is not serious offender in that area, but a few belly shots should confirm.

NOTE:
Conveyor belt material is much better than lawn edging, but more expensive too.

In short, most aero in this forum deals with drag, drag forms on the aft part of the car after the highest part of the roof.

Suggestions will follow photos.
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Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html

Last edited by kach22i; 11-10-2020 at 05:38 PM..
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Old 11-10-2020, 05:58 PM   #6 (permalink)
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Definitely a grille block.

2 in 1 in terms of benefits as it allows for faster warm-up times and provides an aerodynamic advantage.

Just make sure to consider all the variables when determining the grille block area. Such considerations can be : ambient temperature, cooling requirements (engine, transmission, etc). Choose a durable material as it will get beaten up, especially in the Winter.
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Old 11-10-2020, 07:05 PM   #7 (permalink)
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Quote:
Originally Posted by kach22i View Post
In short, most aero in this forum deals with drag, drag forms on the aft part of the car after the highest part of the roof.
kachi22, I don't mean to single you out here, but at the same time this needs to be addressed: This is way too simplistic, but it's one of those "rules of thumb" that get thrown around here constantly. Drag is one of the three components of the aerodynamic force resultant that forms from pressures acting on the entire surface of a car.

As I posted about in another thread recently, a well-shaped car can have a lot of forward-facing surface area subject to negative pressure differential from atmospheric--the implications of which (that this reduces overall drag because of the contribution of thrust) appeared to go over the heads of nearly everyone who subsequently commented in the thread.

Incidentally, Julian Edgar later told me that Rob Palin, former Tesla aerodynamicist, said that lowering pressures on forward-facing surfaces by careful shaping was a key strategy for reducing drag in the development of the Model S. This runs counter to the prevailing wisdom here that beyond a certain amount of rounding--just enough to support attached flow--shaping of the front of a car has little to no effect on drag and everything important happens at the back because the prevailing wisdom is overly simplistic to the point that it is not true.
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Old 11-10-2020, 07:31 PM   #8 (permalink)
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The conversation is already in the weeds.

OP is only nineteen and this is their first post. (Hi again. Did you lurk much?)

I can't find a picture, and it's torn out of my example; but the Audi 80/Passat/Dasher has an offset radiator and should have a sliding fiberboard panel in the radiator ducting that was apparently controlled by a wire cable. A variable grille block if you will.

As important as some blockage is a proper bell-mouth intake and well-thought out venting (back corners of the hood vs wheelwells).
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Old 11-10-2020, 09:42 PM   #9 (permalink)
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Quote:
Originally Posted by freebeard View Post
The conversation is already in the weeds.

OP is only nineteen and this is their first post. (Hi again. Did you lurk much?)
So rather that try to give him (and others) correct information, it's better than we continue to spread misinformation? And trying to correct that misinformation is a conversation that's "in the weeds"?

How pathetic.

No wonder I've stopped 99 per cent of my postings - what's the point?
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Old 11-10-2020, 09:58 PM   #10 (permalink)
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Hi there, JulianEdgar.

While we wait to see if the OP has been scared off, my point was that the information, correct or not, is overly [non-]specific.

kach22i probed for a use case. Another user [couch]Tyrant at large[cough], took up your torch. I think it was a strawman argument.

Irrespective of the merits of any particular suggestion, it needs to be pertinent to a specific case. Surely you appreciate case-by-case A-B-A testing.

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