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Hi @all,

does anyone have exact figures regarding the air drag coefficient of the Honda CRZ?
My old ED9 one has got 0,3 CW.
I am still wondering whether this value has been improved with the new Honda sport car generation. Even more interesting would be the value of the upcoming Honda CRZ R-Type. By the way does anyone know the release date of the CRZ R-Type?

kind regards

The Pilot
 

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Drag coefficient

Here's another link to an article that mentions the drag coefficient of 0.30.

Honda's new CR-Z taps the past to drive its future

I was looking too and noticed the other link is now dead.
But I found other articles with later publishing dates that said Honda had yet to publish info on the drag coefficient. So not sure what's up with that.
0.30 does seem less than stellar for a hybrid.
 

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Mazda3 Hatch - 0.31
VW Golf - 0.32
Ford Fiesta Hatch - 0.33

Consider the cars shape 0.30 is still pretty good. A Prius/Insight tear drop is the best for passenger cars. Sedans uses the popular 4 door coupe shape or plenty of aerodynamic tricks. Hatch models don't do will without tadpole design or tricks like highway speed closing grills and special alloy wheels.
 

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If anyone is bored, find an easy way to plug up the lower portion of the honeycomb grill. DIY fuel economy boost.
Is this safe?

I thought the front grill allowed air flow to assist cooling down the radiator in conjunction with the radiator fan thus cooling down the engine. Plugging this would consequently cause unnecessary overheating issues. Dunno....:mellow:
 

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Is this safe?

I thought the front grill allowed air flow to assist cooling down the radiator in conjunction with the radiator fan thus cooling down the engine. Plugging this would consequently cause unnecessary overheating issues. Dunno....:mellow:
Any modern vehicle is designed to run in a range of climates, including high humidity Forida or sun baked dry Arizona. If you lived in Orlando with 93 degree temps blocking the grill would be a bad idea but for those of us living in 28 degree Connecticut don't need all that cooling.

Plexiglass with holes drilled in it and zip-ties holding it to the grille. I've done this with civics in the past.

Alternatively you can use coroplast sheets (political signs are made of it, think plastic cardboard).

Here's a good link to get started:
DIY - Front Grill Block - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com
I'm a bit against any method that makes the car look like it had a cheap ghetto repair job. On my Civic I used pipe insulator which stayed put inside the chrome grill without being really noticable from the exterior.

Ok and some honesty I'm a little lazy to cut, paint, and zip tie some plastic :blush:
 

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I'm a bit against any method that makes the car look like it had a cheap ghetto repair job. On my Civic I used pipe insulator which stayed put inside the chrome grill without being really noticable from the exterior.

Ok and some honesty I'm a little lazy to cut, paint, and zip tie some plastic :blush:
Black zip ties, black coroplast or black painted plexiglas actually doesn't look bad. I've done it on a few cars and it works like a charm.

I didn't paint the plexi at first on my civic, but after like 10k miles it started to fog because of the highway grime etching it, so I painted it black to match. I later had it sprayed with the body's paint and it looked really good. I gained about 5mpg across the board.

Just like with anything, there are ways to make it look like ass and be functional, or there are ways to make it look good. If you wanted, you could even take the bumper off the crz and put the coroplast on the inside-side of the grille.
 

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On first appearances the CR-Z looks like a nice and slippery shape, but in reality it's just too short to be truly aero efficient. There are a lot of forces in play, but basically the longer an object is, the more aerodynamically efficient it tends to be and the higher it's theoretical maximum speed. That's why supercars built with top speed in mind tend to be very long (think of the Jaguar XJ220 and Maserati MC12).

In ordinary cars, having more length means that there is time for the air to hit the front of the car, draw back in around the body and flow smoothly over the back. In a shorter car, the air doesn't really reach that stable state and it's far harder to control the flow over the rear, resulting in little eddies and vortexes that bump up drag. If you watch touring car races, in particular the BTCC, you'll see on the tracks with longer straights that the Chevrolets, BMWs and Vectras have a straight line speed advantage over the Civics (and they would over the Focus too, if not for their pesky LPG and turbos) once the initial acceleration is out of the way.

That said, the CR-Z actually okay for such a short car. For starters, it's 0.3 Cd is better than most compact/hatchback cars and way better than the EDM Civic, which weighs in at a hefty 0.36. Going the other way, the Insight is only 0.28 and the Prius, I think, 0.26 so it holds up pretty well.
 

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So what can you do to improve the CD?

- cover the grill?
- roof spoilers?
- front splitters?
- rear "duck tail" spoilers?

Does any one know?
 

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Hate to tell ya, but what would you gain by blocking the grill besides less airflow to the radiator/condensor? The A/C condensor can reach 300psi in 100 degrees and needs as much air flow as possible for cooling. Permanent damaged can result to the A/C compressor due to overheating, and no one likes a car with poor performing A/C in super hot temps anyway.
If you think about it, so your taking and moving the wall of air from the radiator to the bumper.... It's difficult to describe, but your still pushing the same amount of air... The new grill I installed opens the entire area up( as you may have seen from the picture I posted other thread... Noticed no differences in MPG. Still averaging 38 mixed highway/city.
 

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Taking an aero view of the car, there's relatively little you can do do improve things. Personally I'd always be reluctant to block off the grill in any way. The car is designed to take on that amount of air and between cooling the radiator, A/C and actual intake for the engine itself that's not something I'd like to skimp on.

Similarly, taping up the shutlines can also be counterproductive. The slightly larger than normal gap at the bottom of the hood is an actual design feature, which does things with (I believe) boundary layer air flow and causes the air to stay close to the line of the car rather than deflecting up and over it, leaving a low pressure area. It may look a little strange but it actually increases MPG and is a feature first seen on the Mazda RX-8.

To my eye, the only area that looks a little suspect is the flared rear arches, which may create a smallish turbulent zone behind them. Not sure what could be done about that, while remaining street legal.
 

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Hate to tell ya, but what would you gain by blocking the grill besides less airflow to the radiator/condensor? The A/C condensor can reach 300psi in 100 degrees and needs as much air flow as possible for cooling. Permanent damaged can result to the A/C compressor due to overheating, and no one likes a car with poor performing A/C in super hot temps anyway.
If you think about it, so your taking and moving the wall of air from the radiator to the bumper.... It's difficult to describe, but your still pushing the same amount of air... The new grill I installed opens the entire area up( as you may have seen from the picture I posted other thread... Noticed no differences in MPG. Still averaging 38 mixed highway/city.
If you look under the hood the intake for the engine is way up near the upper grill portion above the licence plate (if you have a front plate). Below all this is just open honeycomb grill where air can rush in. With most of the grill blocked air is just rushing over the car rather than creating little eddies of air.

Cars are designed for a variety of climates which is why the grille is plenty big. Many of us live in areas where the weather dips fairly cold. As of this moment it is 25 F outside where I live. We had some snow yesterday at the elevation I live. I don't need to worry about an over heating radiator. Blocking the grill also has the bonus of helping the car warm up faster since cold air isn't as easily displacing warm air inside the engine bay.
 

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If you look under the hood the intake for the engine is way up near the upper grill portion above the licence plate (if you have a front plate). Below all this is just open honeycomb grill where air can rush in. With most of the grill blocked air is just rushing over the car rather than creating little eddies of air.

Cars are designed for a variety of climates which is why the grille is plenty big. Many of us live in areas where the weather dips fairly cold. As of this moment it is 25 F outside where I live. We had some snow yesterday at the elevation I live. I don't need to worry about an over heating radiator. Blocking the grill also has the bonus of helping the car warm up faster since cold air isn't as easily displacing warm air inside the engine bay.
Hahaha! Your a funny fella. Maybe a snow plow would help with the aerodynamics...:rolleyes:
 

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Hahaha! Your a funny fella. Maybe a snow plow would help with the aerodynamics...:rolleyes:
:mellow:

Not sure if serious. With a block in place in a scoop shape grill like ours you have a nice little bubble of air that in theory will help air slip easier over the hood. Plus it helps with the start of your commute, lets the engine warm up faster by slowing the exchange of hot & cold air.

It was an easy task on my Civic since pipe insulator foam fit fight into the spaces around the chrome grill.
 
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