Tuft testing video: Honda Insight (2000) front wheel well design

[jime57]

Originally Posted by MetroMPG

Honda didn't leave a ton of room for improvement, but I still think there is some room. Without going to a full, articulated skirt, we could do:

- completely smooth wheel covers, as mentioned
- gap fillers that extend the "sharp" top & forward portion of the wheel arch a bit closer to the tire
- boat tailing aft of the front tire (on the bottom of the forward part of the rocker panel)

Yes I agree that those changes would improve it a bit, but I think I see lower fruit on the vine. I already have a lots of mods on my 2001, but I'm onto the back/boattail next. Lots more productive, IMO.

[MetroMPG]

Agreed! Definitely lower hanging fruit to be found elsewhere rather than tweaking this part of the car.

I just wanted to suggest that as interesting and good as the wheel arch design may be, there's still some room for improvement.

[user removed]

Another thing is the large exit openings in the inner skirt (where it tie rods connect to the steering knuckle) to allow high pressure air in the engine compartment to escape into the wheel wells.

regards
Mech

[HyperMileQC]

Really good video! Thanks for the info. I was also wondering if the front wheel arch from the Insight was good. It seems like Honda put alot of effort on this. IMO I don't think front wheel skirts would really help, but only A-B-A would show the truth...

[Piwoslaw]

If they did their homework on this and it actually works, then why didn't this show up in later models? It's not more expensive than normal, sharp-edged wheel wells.

[MetroMPG]

Because it looks kinda funny?

You could ask the same question about, for example, rear bumper covers with squared off trailing vertical corners that promote clean flow separation. They are fitted to higher efficiency versions of otherwise regular high volume models like the Fit EV (but not on the regular Fit), or the Camry Hybrid (but not on the regular Camry), and the Accord Hybrid (but not the regular Accord). Automakers say the sharp trailing edge design reduces Cd, so why don't they just do it across the model line?

[jime57]

Originally Posted by HyperMileQC

IMO I don't think front wheel skirts would really help, but only A-B-A would show the truth...

True, but testing on an Insight is darn hard to do. The car is ultra sensitive to a whole host of factors, not the least of which is percentage lean burn, so it is practically impossible to do A-B-A testing with any accuracy. For my modding ideas, I rely of things which I can verify in Hucho, or tests on other cars, either my own or others. I have improved the aero on one of my Insights such that I "seem" to be getting about 7-8 MPG more as compared to my baseline Insight.

[PaleMelanesian]

You can coast-down test for aerodynamic mods.

[MetroMPG]

Originally Posted by jime57

it is practically impossible to do A-B-A testing with any accuracy.

I respectfully disagree. But again with this condition: I have an ideal test route - straight, flat, level, practically devoid of traffic. (I think we've gone through this before!) Also: I will only test with the hybrid system disabled, as it can throw variability into the test (hidden background charging, etc).

Andrew - coastdown testing is an alternative, for sure.

Though 3-Wheeler posted about coastdown testing in his Insight and he had a lot of difficulty getting reliable results, even without changing anything. I have a few ideas on why he had trouble, and hope to do an Insight coastdown A-B-A test this fall to try out a deep air dam.

[aerohead]

This is just some thinking out loud,but I am considering that the benefits are derived more in a crosswind.
The radius forms a sort of exoduct,much like a nice 1.5 radius ell found in plumbing and HVAC design.My Beechcraft Bonanza V-Tail has this at the engine bay extractors.
In a crosswind,as the air attacks from a vector off to the side,the wheel well trailing edge radius would provide a beneficial pressure gradient,forcing the airstream against the body,preventing a 'jet' to form as you may see during rain events,as the air erupts out the wheel well,in completely separated flow.
Since road vehicles typically see a crosswind,Honda may have designed for this.