Matt you'll find this interesting.

[Capcom]

Originally Posted by Compaq888

Saw a video of the undercarrage of a Ferrari F430, NSX, GT3 and other sports cars. The Ferrari had EVERYTHING covered under the car. Even where the engine is there is a cover there against wind.

But Ferrari's engine and most other sports cars' engines and exhaust pipes and catalytic converters are located at the back, besides engineers really know what they are doing when they completely cover underfloor of a car.

My biggest fear is: if we cover the underfloor of the car by metal panels maybe gas tank can be overheated by catalytic converter, eghaust pipe, mufflers...

[Compaq888]

The catalytic converter is nowhere near the gas tank. The muffler is far from the gas tank too. The pipe of the exaust is shilded by metal from the gas tank to absorb the heat. I'm not going under the car with a propane torch, I'm just covering areas where it's not smooth. The difference will be night and day at freeway speeds. Not only will the car have more top end but it will improve airdonamics. Improved airdonamics= less fuel to push the car because of less wind resistance.

This project is diffenetly for spring/summer and it doesn't require measuring electricity or playing with chemicals. All it requires is making sure the metal/plastic doesn't touch any of the suspension components or block areas where the car needs to be cool. I'm thinking of not covering the engine compartment area, just the rest of the car. Not only it will make it easy to fix stuff under the engine but it will also help cool the engine bay.

[Capcom]

I know you will be doing this for improved air-do-dynamics

Anyway, youll never know, i would just put an extra electronic thermometer under the gas tank and always watch the temperature from the drivers seat especially during initial stages of development.

I am thinking about covering underfloor of my car at summer too. And also here there is a wind tunnel where i can test the cars wind drag before and after the modification..

[Compaq888]

I seriously doubt the metal will block the heat from coming out. My car already has a drag coefficient of .32, but I'd like to lower it under .30

By using the Formula 1 and top end cars designs we can improve the fuel economy on our cars. I always look at those cars for ideas. Also If you look at Honda cars they are using this technology too. Notice how much smoother the undercarriage is on the new accord, or how the front looks very airdonamic. Also look under the car where the spare is placed, it's very smooth. Don't forget the new civic too.

[Capcom]

I see.
My car's (Opel Vectra B) underfloor is an aerodynamically chaotic environment. Yet its Drag coefficient is 0.28cd.. Lowering that value to "Opel Calibra"'s 0.26 drag coefficient would be marvellous.

[Compaq888]

If it's already .28 then I think .25 is very possible.

[MetroMPG]

I'm thinking of not covering the engine compartment area

you'd be missing out on a good opportunity to reduce drag. here's an article (free preview; paid reg'n required) about a 1st gen prius which reduced hwy fuel consumption by 10% with just the front undertray. you could always include a trap door in the front pan to make oil changes easy (that's what i'm planning).

as for cooling airflow, don't forget, you need to leave a fairly large cut-out to permit lock-to-lock steering of the front tires. the openings are large enough for air to escape from the engine bay through there.

ferarri's, etc...

one of the interesting things i've learned about aerodynamics is to keep in mind when you're looking at those cars that there are actually 2 opposing aerodynamic theories at play. one is to reduce drag for higher speeds, the other is to increase drag to create downforce for better handling at those higher speeds.

the underbodies of high-end sports cars and F1 type cars, while smooth, are designed to create a low pressure zone the car that creates downforce. it actually takes more power to propel a car with that kind of underside. rear wings are the other way downforce is created while also creating more drag - talking high-end sports cars here. (the max-mpg vw bug is an exception - its wing helps correct an otherwise aerodynamically poor shape and makes it more efficient.)

don't get me wrong, smooth underneath is good. you'd have to shape the underbody in a very specific way to cause downforce as a result - we won't cause that by putting belly pans on our regular cars.

[GasSavers_DaX]

I got to check out a Ferrari 360 Modena pretty good about 3 years ago [my mother's co-worker's husband's weekend car]. The undercarriage is completely smooth, and the cockpit feels excellent. I tried bribing him into taking me for a spin, but was turned down. I at least got some tuff photographs of me sitting in a sweet ferrari.

[Compaq888]

It sucks that I can't see the rest of the article.

I'll see what I can do with the engine bay. I'm just hoping to do this and the generator and be done with the car.

If you have access to the article can you copy the page, not the link since that is trying to get around the registration. I mean by taking a pic of your screen and posting the pic here.

All you have to do is press the "Print Screen" button on your keyboard, it's right next to the Scroll lock button. Then you open "Paint" and press Edit tab and click on paste. If you need me to host it I'm sure I can do it for you.

[MetroMPG]

no offense, but i'm kind of reluctant to copy & paste the entire article (it's actually 2 parts).

i registered (paid) to access that site's archive, primarily for a number of articles on DIY aerodynamics and lots of good photos. i think it's important to support sites that offer quality info and ask a reasonable fee.

but i will sum it up: the article goes over how he prototyped and tested the front undertray and also front wheel deflectors. both changes improved mpg, but he ditched the deflectors because he felt they increased front lift and worsened hwy speed steering feel.

here's what the tray looked like:



btw, this is the same prius that i mentioned in the turbo thread - after the undertray, his next project was a low psi unit which also increased mpg a few percent.