Aero Crosstour- Squeezing blood from a stone

[Chonk_Master]

It's probably not going to happen. If I thought it was absolutely necessary to improve MPG, I'd do it but this project has a shoestring project. And other maintenance concerns, like my awful, warped rotors.

The link between driving behavior and MPG isn't exactly complicated. I've watched plenty of factory instantaneous MPG gauges and I can't think of a single instance I was surprised by the reading. I've read the 65+ and 100+ hypermiling tips and nothing stuck out as particularly novel. There were a few things that were interesting but most of those fell into a "useful but not practical for me" category.

Several others fall away because they drastically alter the driving experience past the point I'm willing to accept. I'm looking for 25 MPG, some insight into aerodynamics, and some experience fabricating here. Raising tire pressure may have gotten me to 23 but I won't know for a little while yet. If I see improvements toward that after each mod by measuring the MPG after, let's say, three tanks (A-B-A style), I'll be happy. If there's no observable improvement, I'll consider it one of the small improvements that add up. If there's an observable loss, off it goes.

[freebeard]

And I'll look up those instantaneous MPG apps because what the heck. I've been using the VCM eco light as a bellwether for now.

Should I presume that's OEM? That would be the low-ball baby step.

I'm making payments on an 1990 XFi that has an Eco light. Even my 1979 Dasher doesn't have that feature. They both can get 45mpg.

[Chonk_Master]

It is. I don't know what you know about Honda's VCM but it allows the V6 to operate on 6, 4, or 3 cylinders. It does so automatically based on several inputs, as far as I can tell.

It seems to follow an instantaneous MPG tracker's behavior fairly closely. Heavy throttle, heavy acceleration, going up hills, etc. all switch the VCM system off. Highway coasting, light throttle, coasting down a hill, etc. all switch it on.

Again, I've never looked down expecting it to be on or off and been surprised.

[Chonk_Master]

Well, small update on lowering. K2 and Megan both emailed me back today and said they really don't recommend the Accord V6 springs for the Crosstour, citing a spring rate that was way too low.

No surprised but they also tried the coilover upsell, so who knows? Jokes on them, I'm broke.

Looks the long term project timeline just got 'cut springs' added to it.

[Chonk_Master]

Question about drag coefficient for anyone who knows: I got a drag coefficient of "56/44" from a random auto blog. Comes out to 1.27

This is almost as high as a flat plate placed perpendicular to flow, the Empire State Building, and Usain Bolt.

Does that number sound right? I knew the Crosstour was tall and wide but holy smokes.

[Ecky]

Definitely not right. Expect it to be somewhere between 0.25 and 0.40. multiple the coefficient (Cd) by the frontal area (A) to get the total drag (CdA). I'd expect that to be in the 2.0-3.0 range.

Edit: that sounds more like the weight distribution.

[Chonk_Master]

How strange. Of course, like most of the cars I've owned, there's no data out there. A website called Auto-Catalog claims to have a full performance review with the numbers but their site isn't loading.

Weight distribution looks much more likely.

Looks like coastdown time and MPG will be king after all.

[aerohead]

Originally Posted by Chonk_Master

Question about drag coefficient for anyone who knows: I got a drag coefficient of "56/44" from a random auto blog. Comes out to 1.27

This is almost as high as a flat plate placed perpendicular to flow, the Empire State Building, and Usain Bolt.

Does that number sound right? I knew the Crosstour was tall and wide but holy smokes.

That ratio is meaningless.Cds are never expressed like that.
I exhausted GOOGLE,attempting to find an official Cd from Honda Motor Co.
The second-gen Insight was rated at Cd 0.28.The Crosstour ought be in that territory.

[Chonk_Master]

Now that you mention it, do you think comparing the front cross sectional area of the Insight and Crosstour could confirm that?

I know that's a relatively small part of the equation and I'm not necessarily sure that's the area used when measuring Cd or D for autos.

[freebeard]

...that's a relatively small part of the equation...

It's a multiplier.

Find a black on white silhouette of the two models, apply a Gaussian Blur filter to it's max and read the RGB value for each. The difference should be proportional without a lot of fussy outlining.