Gen 2 Prius ecomod thread

[Hypermiler1995]

Or would a belly pan make little difference when combined with an air dam?

[vskid3]

Belly pan is generally considered to be the best option, but air dams are easier (especially for trucks). I would go with the belly pan. The Prius' belly is already pretty good, but there are a few areas that could use improvement and shouldn't be too difficult.

[Xist]

There are two camps here, that air dams provide most of the benefit of a belly pan, for a fraction of the effort, and those that say that air dams are bandages that do not solve the problem. Not many people have done A-B-A testing on it, or at least have not updated Car MPG Efficiency Modifications Main - EcoModder. The very small amount of data listed indicates that air dams are better, but we need more data!

Who said that air dams are bad for Prii?

One point is that you should be able to tell if your air dam works, the usual issue is whether it maintains rigidity at higher speeds. My Civic is naturally low and I can still jack up my car without a problem. I do not know what other drawbacks there might be. However, with a belly pan, you would need to remove it from time to time, and if it gets damaged, it can make your car less aerodynamic than stock until you fix or remove it.

[Hypermiler1995]

Originally Posted by Xist

Who said that air dams are bad for Prii?

I have read that since the bottom of prii are already reasonably smooth, that an air dam helps very little for aero, and adds frontal area.

[RedDevil]

Air dams and belly pans both lower drag under the car but in an opposing way.

Air dams raise the pressure ahead of the car (enlarge the more or less stationary bubble of air).
That's good because it makes the air flow over the car rather than under.
But the air dam cannot block all the air from flowing under the car if you want a practical ground clearance.

Belly pans allow the air to keep flowing under the car so they would lower the pressure ahead of the car, diminishing the size of the bubble. It directly reduces drag under the car so it can't be bad.
But if the air would move less fast (rather, more with the car) then the drag would be even lower.

I'd think the combination of a moderate air dam and improved belly pan would work best.
That would cause the air flow to follow the original (designed) pattern more or less, but with even less drag under the car than with either measure alone.

[Hypermiler1995]

If the belly pan connects to the bottom of the air dam, then the drag area from the air dam will be removed.

[Xist]

Originally Posted by Hypermiler1995

If the belly pan connects to the bottom of the air dam, then the drag area from the air dam will be removed.

Belly pan proponents state that the only good an air dam truly does is when it serves as an attachment point for a belly pan.

[Hypermiler1995]

Originally Posted by Xist

Belly pan proponents state that the only good an air dam truly does is when it serves as an attachment point for a belly pan.

And what do real tests say?

here is what I came up with, best to worst:

1 lower stagnation point nose cone with belly pan
2 belly pan with front connected to air dam
3 belly pan and air dam
4 belly pan
5 air dam

[Hypermiler1995]

Working on rear wheel covers, having trouble with the mounting setup.

sorry about the picture! Just click it!

[Hypermiler1995]

I want some opinions:

Shark fin antenna, does it help any, or just looks?
Has anybody removed the rear wiper and wished they hadn't?
Does the upper grille block need removed in the summer?
Should I put boattailing behind the front wheels, or inner and outer side skirts? (I live on a dirt road.)
What should I NOT cover with a belly pan? (going to use metal, no melting hazard)
What are the advantages of a scangauge over the factory prii system?
Current tires are Goodyear Integrity 185/65/15's are these Lrr, and what is better?

PLEASE POST MODS!!!!