Fuel Saving Thread: Motoring Tips & Tricks

[AWOC]

The problem with cars today is aerodynamics. Yes they are way better than they used to be be not nearly enough where they need to be. One area is the under neath of cars today. Unless you are riding 1/2" off the ground the drag created by the undercarriage of your car is a huge problem. The weird floor shapes and exhaust pipes create a lot of drag in this higher pressure area. The drag created by the wheel wells are also an aerodynamic mess. More needs to be done in these areas to improve fuel mileage.

Here's what Honda did for the undercarriage. Seems cheap and with little assembly line work.
http://world.honda.com/NSX/technology/t3.html

Undercarriage and wheel well.
http://www.insightcentral.net/encyclopedia/enaero.html

Manufacturers need to do the same for all passenger cars!

 

[baywax]

The problem with cars today is aerodynamics. Yes they are way better than they used to be be not nearly enough where they need to be. One area is the under neath of cars today. Unless you are riding 1/2" off the ground the drag created by the undercarriage of your car is a huge problem. The weird floor shapes and exhaust pipes create a lot of drag in this higher pressure area. The drag created by the wheel wells are also an aerodynamic mess. More needs to be done in these areas to improve fuel mileage.

Here's what Honda did for the undercarriage. Seems cheap and with little assembly line work.
http://world.honda.com/NSX/technology/t3.html

Undercarriage and wheel well.
http://www.insightcentral.net/encyclopedia/enaero.html

Manufacturers need to do the same for all passenger cars!

I totally agree. So far it has been style dictating the design instead of efficiency. Whereas a design based on efficiency will be more pleasing in more ways than simple aesthetics. I don't get it.

 

[mgb_phys]

A front air dam will stop a lot of the air going under the car.

But making the underside smooth will create downforce which while improving cornering and acceleration (the reason it's done in F1 cars) will overall increase drag - since it effectively makes the car heavier.

 

[mheslep]

A front air dam will stop a lot of the air going under the car.

But making the underside smooth will create downforce which while improving cornering and acceleration (the reason it's done in F1 cars) will overall increase drag - since it effectively makes the car heavier.

s/drag/rolling resistance/

 

[mgb_phys]

Yes - I meant drag in the sense of retarding force.

 

[AWOC]

A front air dam will stop a lot of the air going under the car.

But making the underside smooth will create downforce which while improving cornering and acceleration (the reason it's done in F1 cars) will overall increase drag - since it effectively makes the car heavier.

How's making the bottom of your car smoother going to create down force, and increase drag?? I still don't understand how a few light sheets of plastic are going to me the car heavier. If anything it will create lift and less drag!
Formula cars are not a good example because they way they channel the air out is a science and different because we're not going to be traveling at 200 mph anytime soon. The way the air is channeled out is to keep the car steady at those kind of high speeds.

 

[mheslep]

How's making the bottom of your car smoother going to create down force, and increase drag?? I still don't understand how a few light sheets of plastic are going to me the car heavier. If anything it will create lift and less drag!
Formula cars are not a good example because they way they channel the air out is a science and different because we're not going to be traveling at 200 mph anytime soon. The way the air is channeled out is to keep the car steady at those kind of high speeds.

Bernouli's principle. The idea would be that the air will flow faster past this new undercarriage, and all else being the same, faster moving air exerts less pressure. Thus the pressure of the faster moving air under the vehicle now exerts less pressure on the bottom of the vehicle. Air flow pressure on top has not changed; the net result is more downward force on the vehicle.
http://en.wikipedia.org/wiki/Bernoulli's_principle#Compressible_flow_in_fluid_dynamics

 

[mgb_phys]

Thank you mheslep - the funny part is that in the link AWOC provided Honda claim more downforce as the main advantage!

 

[AWOC]

Thank you mheslep - the funny part is that in the link AWOC provided Honda claim more downforce as the main advantage!

Yeah sorry guys. I took Fluid Dynamics last semester and very aware of Bernoulli's Law, but I got confused because if you think of it as an airplane wing where the faster moving air is underneath and the slower up top it would create lift. I forgot that flow goes towards the lower pressure, but that's why you guys are here to remind me and threads like this are great little refreshers.
So anyways.. by putting a lip that allows no air underneath the car is the best thing to do, but does anyone know of any real proven gains from this?

 

[du nuthin]

And the energy to do this comes from ?

Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species.

Water-Diesel-Emulsion fuels can capture some of that heat of combustion which is essentially a waste heat that need to be removed.

A mixture of one part water and two parts diesel can deliver the same power as pure diesel.