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Old 08-22-2009, 06:39 PM   #1 (permalink)
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MR2 rear wing - keep or lose?

I have just bought a MR2 mk2 with a dead engine to convert to electric.

It has a big wing on the back which I am sure did something for the styling back in 1991 and may have had an effect at some speeds but for my EV I want good aerodynamics.

So, should I keep or remove the wing?
Does anyone know what sort of difference it makes to the aerodynamic drag?




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Old 08-22-2009, 07:31 PM   #2 (permalink)
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As far as the wing, it looks as if it is just there to create downforce.
Eventhough it looks awesome, I would remove it.

The side butresses behind the back window would make excellent mounting points for a piece of clear lexan. ( Since you no longer have to vent the heat from the ICE. )

Nice car. This is going to be one interesting EV !

One more thing : you are going to replace the wheels right ? ( They look great, but really stir up the air. )
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Old 08-22-2009, 10:23 PM   #3 (permalink)
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Looks useless. With the notchback instead of a hatch, I doubt the MR2 creates lift back there that needs to be cancelled.

I don't think it would be worth changing wheels. What is he gonna do, put steelies on a sports car? Then again there may be some more aerodynamic alloys out there.
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Old 08-22-2009, 10:37 PM   #4 (permalink)
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It's not purely cosmetic, so I'd leave it. Downforce at speed is a good thing, if you're thinking about stability. Your wing's shape actually will produce a bit of lift reduction.

It does add a slight degree of drag, but removing it will probably give you (just a guess) maybe a quarter of a mile per gallon extra, but you'll feel a little looser going down the freeway. Not good if you need to swerve to avoid an accident.

If you're going to electric, definitely keep it, because there's no MPGs to worry about.

I'd LOVE to have a car like that.
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Old 08-22-2009, 10:45 PM   #5 (permalink)
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It might actually make control worse at high speed, by reducing force on the front tires. Look how far back the wing is. And it's already pretty light in front.
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Old 08-22-2009, 10:48 PM   #6 (permalink)
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Quote:
Originally Posted by Hermie View Post
It's not purely cosmetic, so I'd leave it. Downforce at speed is a good thing, if you're thinking about stability. Your wing's shape actually will produce a bit of lift reduction.

It does add a slight degree of drag, but removing it will probably give you (just a guess) maybe a quarter of a mile per gallon extra, but you'll feel a little looser going down the freeway. Not good if you need to swerve to avoid an accident.

If you're going to electric, definitely keep it, because there's no MPGs to worry about.

I'd LOVE to have a car like that.
Yeah, actually, there are MPG's to worry about when you're going electric. You're still getting charged for the "fuel" as it were, and there is still pollution that is a part of your vehicle, which comes directly from the use of your vehicle's "fuel".

That wing will do just about nothing, at any speed that the average EV will travel. Chances are, if he's doing a conversion like most of the other ones on this site, and most @home conversions in general, he's not going to even be doing 60 MPH.

While I'm sure you have unlimited knowledge about exactly how a wing-type spoiler will hamper/degrade fuel efficiency, the minimal effect on economy that you claim that spoiler will have, is the same minimal effect on downforce at road speeds that it will have.

Include the fact that as an EV, that car will weigh ~150% of what it weighs now, and the aerodynamic downforce you allude to is of no consequence. If that wing can create 50% of the car's weight in downforce at 60MPH, it's creating a HUGE amount of drag as well.

It's simply not going to be necessary once he converts to EV, and it was never necessary with the gas engine, either, unless the operator were driving illegally.
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Old 08-22-2009, 11:00 PM   #7 (permalink)
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Quote:
Originally Posted by winkosmosis View Post
It might actually make control worse at high speed, by reducing force on the front tires. Look how far back the wing is. And it's already pretty light in front.
It's not nearly far back enough to have a lever/fulcrum effect on the front. The MR2 is a mid-engine, rear drive car, so the back end is going to have more weight. Intertia dictates that the greater the mass, the more it resists change. Rear-heavy cars will tend to oversteer, meaning the back end will want to switch with the front when traction is lost (from slippery roads, for example). The same goes with front-engine, front wheel drive cars. They tend to understeer from the weight balance being in the front (except during high-speed corners while braking. The lighter rear plus braking will lead to rear-wheel traction loss, resulting in brake-induced oversteer, but it won't try to spin you around like a top.).

Quote:
While I'm sure you have unlimited knowledge about exactly how a wing-type spoiler will hamper/degrade fuel efficiency
There's no call to be rude.

Quote:
and there is still pollution that is a part of your vehicle, which comes directly from the use of your vehicle's "fuel".
Not if you've got a solar-powered charger.
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Old 08-23-2009, 12:35 AM   #8 (permalink)
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Quote:
Originally Posted by Hermie View Post
It's not nearly far back enough to have a lever/fulcrum effect on the front. The MR2 is a mid-engine, rear drive car, so the back end is going to have more weight. Intertia dictates that the greater the mass, the more it resists change. Rear-heavy cars will tend to oversteer, meaning the back end will want to switch with the front when traction is lost (from slippery roads, for example). The same goes with front-engine, front wheel drive cars. They tend to understeer from the weight balance being in the front (except during high-speed corners while braking. The lighter rear plus braking will lead to rear-wheel traction loss, resulting in brake-induced oversteer, but it won't try to spin you around like a top.).



There's no call to be rude.



Not if you've got a solar-powered charger.
You don't consider it rude to speak as though you are an authority on a subject, even though you don't have any references or real experience in the field to back you up?


What do you think it took to make that solar powered charger?

Also, how much money would you like to spend on a budget EV conversion? (I realize the OP never said it was a "budget" conversion, but the assumption can be made based on the majority of users here and elsewhere that have done similar projects.) Whole house sets run about 30k installed, one just to charge a car would probably net at least $4k, and would be a waste of resources. It would never pay itself off.

The carbon payoff for solar panels (depending on how long they last, the amount of power they produce, and where they were made) is actually more than their expected usable life span.

At current prices, they'll pay themselves off in electric bill savings in something like 30 years... more than they'll actually last for.

In case you'd like to research before you rebut:
http://www.google.com/url?sa=t&sourc...ZXzgwR9_1ciCeg

http://www.google.com/url?sa=t&sourc...2oEHUTRNYaf7tA

http://www.google.com/url?sa=t&sourc...nNC3nIS_eSevoQ

http://www.google.com/url?sa=t&sourc...SeHrc32cyMRy5A
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Old 08-23-2009, 12:39 AM   #9 (permalink)
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Quote:
Originally Posted by Hermie View Post
It's not nearly far back enough to have a lever/fulcrum effect on the front. The MR2 is a mid-engine, rear drive car, so the back end is going to have more weight. Intertia dictates that the greater the mass, the more it resists change. Rear-heavy cars will tend to oversteer, meaning the back end will want to switch with the front when traction is lost (from slippery roads, for example). The same goes with front-engine, front wheel drive cars. They tend to understeer from the weight balance being in the front (except during high-speed corners while braking. The lighter rear plus braking will lead to rear-wheel traction loss, resulting in brake-induced oversteer, but it won't try to spin you around like a top.).



There's no call to be rude.



Not if you've got a solar-powered charger.
The MR2 will not necessarily have more weight in the rear, and being a sports car, it's closer to 50/50 front/rear bias. *I actually think it's 42/58 F/R*. In fact, having driven several MR2's, both first and second gens, I can personally say that they're extremely neutral (moreso than most other cars I've driven) while going down the road. They're certainly more stable than V6 Fieros.
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Old 08-23-2009, 02:16 AM   #10 (permalink)
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Please start a build log! I love reading about EV conversions, since I can't have one for myself.

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