Dream Prius (aerodynamic mod exercise for 2nd gen.)

[Nerys]

Wow what a car. Thats pretty (the red dream prius) some questions and concerns. First I would fear driving that car. Its aerodynamic but possibly in the wrong way. IE LIFT. its scarily like an airfoil. How heavy is a prius? I know on some porsches at speed the spoiler comes up for a reason. While the car will never "lift" off the ground it can get loose on the rear wheels to where its dangerous so they added that auto spoiler to kill this lift and prevent that. How do we get aerodynamic but also prevent too much lift from being generated?

I want to work toward seriously aeromoding my Voyager. From the front it has a very nice shape just dirty (protrusions) the rear is gonna be more difficult. IE attaching a rear bubble butt would not be hard but it might be awful large :-)

Mirrors. They are the first things I am going to eliminate and replace them with 2 camera's and miniatures LCD's inside (same with the boat tail ie camera to let me see)

I am also considering REMOVING the tailgate door all together. Getting another from the junkyard and hacking it up so this "new" boat tail can "bolt" right up and function normally as a tail gate. I was also considering an inflatable boat tail. IE deploy it on the highway but stow it in the city since it would add considerable length to the vehicle.

Another question. Shelling the wheel wells. How do I do this? The rear wheels is not big deal but how do you handle the front wheels since they protrude when you turn?

I was thinking the "aeroshell" for the front wheels could also "move" so when the wheels turned enough that the tire was about to hit the aeroshell the shell itself would MOVE to accomodate this. Would ruin the CD but this would never happen at highway speeds. BUT that sounds awful complicated. Is there a simpler solution I am missing?

Roof Racks. I am trying to find a way to aero the roof rack without removing it since I DO use it sometimes. Maybe make the cross spars removable and mold a cap to make the longitudinal runners smooth.

Any other suggestions? I REALLY hope he gets that Red Prius built. Thats gonna be one kick butt looking car :-)

[Daox]

The boat tail on the car will reduce lift. His car will probably handle at high speeds a lot better than a stock Prius should those mods be done.

[basjoos]

The front wheel well covers on my car are piano hinged at the top with 2 low-profile conveyer rollers that contact the side of the tires when they turn sharply. A retraction spring at each lower corner keeps the cover closed when the tires are straight. It only opens for fairly sharp turns. I've been running this setup for about 2 years.

Another approach I have seen is using a stretchy fabric to cover the wheel well with a piece of inner tube rubber sewn in the locations where the tires would rub the fabric.

[Nerys]

Daox if the boat tail end upswept it will decrease lift it if ends downswept it will increase lift. Thats just basic aerodynamics. The overall shape of his prius concept is a lifting airfoil. Now his civic looks pretty neutral (no more or less lift than before) It could also just be the "perspective" of the image I am seeing. Hey Basjoos I wish you could do a higher res version of that red dream prius it really makes me drool :-)

I find the pics of your front wheel covers. INGENIOUS that it just awesome the solution you came up with.

One thing I noticed. I wonder how much of your drag reduction is being eaten up by parasitic drag from the rough joints connects etc.. of your aero fairings? have you given thought to how you would go bout cleaning up the lines? Packing tape applied "taunt" might be a cheap and dirty way to see if it has any measurable effect on short term FE gains before trying for a more permanent solution.

I really do have to say I hate and love you now. You have really planted the "aero" bug in me now for modding my Voyager. Grrrrr :-)

I am a big aeronautics hobbyist and never thought there was a practical way to attempt to clean up my voyager until I saw your civic and these threads. I fly a lot of Rockets where drag is everything performance wise.

We are going to myrtle beach this summer I would love if its close enough to take a look at this car close up. I love taking pictures I could shoot a ton of high res pictures and give them to you or help you put together some detailed descriptions of your work to make it easier for others to replicate and model on it.

I even have an idea for getting those tire boat tails closer to the tires. a Track linked to the suspension so as your suspension compresses the boat tails "move away" from the tires to avoid contact. This way while cruising they can be as close as possible to the tires themselves.

I am going to take some pis of my van tommorrow to photoshop some aero mods onto it to get an idea of what it would look like.

I also have an idea for cooling so maybe I can close up the front end all together using peltiers. I am even thinking I might be able to use the heat of the exhaust system to create the electricity to run another peltier to assist the radiator to compensate for its lack of cooling is I close up the engine compartment some more (grill underneath etc..) not an issue in the winter but would be an issue in the summer. I am even considering a battery powered system to run the cooling depending on what kind of power consumption I am talking about. IE plug the car in when I am at home or at work to charge up the battery so I do not transfer this load to the engine via the alternator.

Might even be able to get rid of the alternator all together this way but would need a way to "reenable" the alternator in an emergency etc.. I wonder if there is a way to install the "clutch" style pully like the compressor has on an alternator. So I can engage and disengage the alternator completely as needed.

GRRR now you got me thinking!!!

Oh one more thing HOW did you figure out the CD of your car? Mathematically (if so how accurate is that) or did you have someone actually measure it? (if so how!)

[basjoos]

I calculated the Cd using the coastdown method described at Instructables.com. I'm located in the upstate of SC, which is at the opposite end of the state from Myrtle Beach, but if you want to drop by to take pics, its ok with me. Small-scale roughness doesn't increase drag and can sometimes decrease drag as with the rough skin surface found on sharks. I need to have some clearance between the wheel boattails and the tire so when my tire tracks lifts some road debris up from the ground and throws it into the air it doesn't get jammed in between the tire and the boattail. Also certain types of wet snow can be picked up by the tires and packed into the wheel well.

[bestmapman]

Update on the "Dream Prius"

I am looking for a salvaged Prius at this time. I have found a company in Dayton, OH that does fiberglass work. I hope to start building this summer.
It is still too early to say that I have started, but I am serious about doing this project.

[Cd]

I am assuming that you will convert your car to a plug in capable version along with the other modifications ?

( As I'm sure you know, you can have this done already by a couple of companies in California. )

You might as well go all the way with it !

P.S. I noticed some comments on the image that you posted. I tinker with Photoshop and do art as a hobby as well.
Whoever Photoshopped that image did a fine job. The image is very convincing looking with all the correct reflections angled correctly. I never would have know it was not real at first glance - and I edit pictures on a daily basis.

[bestmapman]

Originally Posted by .Cd

I am assuming that you will convert your car to a plug in capable version along with the other modifications ?

( As I'm sure you know, you can have this done already by a couple of companies in California. )

You might as well go all the way with it !

If it was only that easy. I would love to convert to a PHEV, but cost is an issue. I will have to be doing one thing at a time.

[Cd]

I would think that the cost of converting the car to a PHEV ( around $14,000 last time I checked ) would be far more cost effective vs. spending the 14,000 on aero mods.
( But this is assuming that you are going to have this done profe$$ionally. )

[Nerys]

Hmmm several problems. You can do most of the aero work yourself should cost no where NEAR $14k unless he wants it as picture perfect as that photoshop. IE he can do a ton of the work himself. In fact he should be able to do that for UNDER $5k if he can do the layups himself and he can do it piece by piece spreading out the cost.

The PHEV upgrade is a fixed massive cost no real room for DIY and its all or nothing. No way to break up the costs.

Plus ANYONE with $14k can and or has done the plug in upgrade. NO ONE has done that wicked aero job so it also has unique points too.

The PHEV has the same problem as a prius. Little chance of recouping the cost of the $14k upgrade on top of the cost of the car in its lifetime in gasoline savings.

$5k worth of aero upgrades has a chance of paying for itself AND the "cool" factor to go along with it :-)