NHW11 Prius Aeromods. <.29 or Bust

[bwilson4web]

You sly dog! I just noticed the boat-tail at the rear!

It always took corners well but I imagine yours is like a refrigerator magnet now. <GRINS>

Bob Wilson

[tochatihu]

Do you drive it with the mirrors folded back? They really are a barrier to your success I think.

[speakchucker]

Originally Posted by orange4boy

I've been working on these over at ecomodder for a while and thought you all would like to see my progress.

How are you going to measure your coefficient when you're done with all this?

[orange4boy]

How are you going to measure your coefficient when you're done with all this?

The only real way short of a trip to a wind tunnel with a big cheque is a coast down test. there is an instructable on it somewhere. From this you can roughly figure your Cd.

Do you drive it with the mirrors folded back? They really are a barrier to your success I think.

I do but since the car is primarily my wife's, they stay. In the following thread by MetroMPG side mirror removal showed a 2.5% improvement.

From:Side mirror drag effect on fuel economy quantified



I should really be testing each mod as I go along but since I don't live near a long flat stretch of highway I have to just stick to proven mods, current trends in aerodynamic cars and my limited understanding of aerodynamics. I'm currently reading The Aerodynamics of Road Vehicles By Hucho.

Apparently the Gen 1 is .29 stock. The Toyota wind tunnel seems to be a little generous but that's all I have to go on at the moment.

[Rokeby]

FYI, "low speed," up to 200 MPH wind tunnel is available for a mere #350/hr.
A real steal.

[orange4boy]

I don't think that's even a drive in tunnel.

I may have a candidate for roll down testing. I will have to do some baseline runs to see how the resolution/variability is. Going to blow this tank average doing tests though.

[bwilson4web]

Originally Posted by speakchucker

How are you going to measure your coefficient when you're done with all this?

Orange4boy and I met over at Ecomodder.com. If you've ever visited "Prius Technical Stuff," Ecomodder is like that but not specific to the Prius. It is one of the best, general, auto-efficiency, engineering groups around. The thing I like best is they have an idea; build it; and test their projects, rigiorously.

Bob Wilson

[orange4boy]

Just found some tires in a narrower size: 165 70 14 that have a similar rev/mile to the OEM RE91s: Nokian Hakka C van. They have a favourable load rating 89/87S. These will have a reduced profile for lower drag. I'm still looking for info on their RR. Most Nokians are LRR though.

There are two references to tire width and drag in Hucho's book. Both refs show a .01 increase in Cd for every 10mm increase in tire width.