11-11-2014, 09:44 AM
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#21 (permalink)
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Master EcoModder
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What I'm saying is, improving on that stuff could well give you better improvements than filling holes underneath. I get the new car thing, but maybe that could just be a challenge to design a "better" grille block or sedan boat tail.
Anyway, rock on. If you do wheel covers, I've been wondering how it would look to do what we often do in my field, and just paste a photoshop image of a wheel over a flat disc. Like this, but full size-
I have too much fun with spinning, abstract shapes to try it myself.
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Last edited by Sven7; 11-11-2014 at 09:55 AM..
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11-11-2014, 10:54 PM
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#22 (permalink)
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Quote:
Originally Posted by Sven7
What I'm saying is, improving on that stuff could well give you better improvements than filling holes underneath. I get the new car thing, but maybe that could just be a challenge to design a "better" grille block or sedan boat tail.
Anyway, rock on. If you do wheel covers, I've been wondering how it would look to do what we often do in my field, and just paste a photoshop image of a wheel over a flat disc. Like this, but full size-
I have too much fun with spinning, abstract shapes to try it myself.
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I tend to tackle projects that are favorable on the cost to time to mpg improvement ratio. I only have about $15 into these underfloor panels, that's $7.50 each. Pretty happy about that. Plus they're low hanging fruit so to speak and lessons learned here will certainly lend themselves to helping out with potentially more ambitious ideas later on. But there are certainly lots of gains to be made on the underfloor. As for wheel covers, they'll be similar to what I've done before, rather workmanlike in execution, but simple and utilizing what's at hand:
Lots has been said about making a flat wheel cover, however I feel it's more important to limit the flow transfer from the wheel to the airflow moving down the side of the car. The above achieved a 2.5% increase in MPG on my Nissan Versa (the largest single gain I ever saw with one change) and they certainly aren't flat perse.
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11-12-2014, 06:48 PM
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#23 (permalink)
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'flat'
Quote:
Originally Posted by woodstock74
I tend to tackle projects that are favorable on the cost to time to mpg improvement ratio. I only have about $15 into these underfloor panels, that's $7.50 each. Pretty happy about that. Plus they're low hanging fruit so to speak and lessons learned here will certainly lend themselves to helping out with potentially more ambitious ideas later on. But there are certainly lots of gains to be made on the underfloor. As for wheel covers, they'll be similar to what I've done before, rather workmanlike in execution, but simple and utilizing what's at hand:
Lots has been said about making a flat wheel cover, however I feel it's more important to limit the flow transfer from the wheel to the airflow moving down the side of the car. The above achieved a 2.5% increase in MPG on my Nissan Versa (the largest single gain I ever saw with one change) and they certainly aren't flat perse.
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Your covers are more a mutilated convex form,which would have a distinct advantage over a perfectly flat cover.And the carbon fiber 'look' is certain to attract attention.
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11-12-2014, 07:12 PM
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#24 (permalink)
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Talk to me more about this mutilated convex form, how is it potentially more advantageous than the pure flat covers?
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11-12-2014, 07:37 PM
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#25 (permalink)
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how
Quote:
Originally Posted by woodstock74
Talk to me more about this mutilated convex form, how is it potentially more advantageous than the pure flat covers?
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The air will separate on the back slope of the leading sidewall,creating a pool of stagnant air within this void (you can see this happening with the Spirit of Ecomodder at the Darko tunnel).
The convexity fills in much of the void,pushing the face of the cover out into the active airstream.The boundary layer of the cover is energized,and little if any stalled flow before flow starts up the trailing sidewall bulge.With a better 'source',the flow has an opportunity for attachment a little further down the trailing sidewall 'sink',minimizing the tire wake.
The convexity is stronger than a flat disc too,so a thinner,lighter cover can be used.
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11-13-2014, 11:39 AM
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#26 (permalink)
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Quote:
Originally Posted by woodstock74
Lots has been said about making a flat wheel cover, however I feel it's more important to limit the flow transfer from the wheel to the airflow moving down the side of the car. The above achieved a 2.5% increase in MPG on my Nissan Versa (the largest single gain I ever saw with one change) and they certainly aren't flat perse.
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Have you posted about this before? If not, would you consider posting a dedicated thread? It's really nicely executed and I like that you tested it.
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11-13-2014, 07:45 PM
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#27 (permalink)
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Quote:
Originally Posted by MetroMPG
Have you posted about this before? If not, would you consider posting a dedicated thread? It's really nicely executed and I like that you tested it.
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No I haven't. I suppose my numbers might not hold up to scrutiny inasmuch as I eschewed ABA testing (primarily out of laziness and lack of patience, always looking forward...) and my only metric was pre-hubcap mileage (5500 miles averaged) and post hubcap mileage (5900 miles averaged). Comparing those two large swaths of mileage and there was a 2.3% increase. I felt it was somewhat undeniable, the gain that is, however I'm sure some would say it would need further testing to confirm. The gain also seemed to fall right in line with what others had seen with the flat wheel covers in general.
I do plan on doing this to the Dart at some point too. The Dodge's hubcaps are as so>
However, I'm annoyed with the hubcaps that are "locked" on to the wheel via the lug nuts and have been considering these>
And I'd just do the same with these as I did on the Nissan, put carbon covers over each "spoke" opening. It takes a bit of time and first I have to acquire some material on the cheap. Working in motorsports, in composites, has a few advantages.
Very intrigued with aerohead's comments in the thread above and wondering if he'd weigh in regarding the two hubcap designs I've shown here (above); does one seem more beneficial than the other? I suppose the black ones appear to have more convexity? The plan is the blank off the opening similar in fashion to Nissan Versa Mk1.
Last edited by woodstock74; 11-13-2014 at 08:53 PM..
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11-15-2014, 07:42 PM
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#28 (permalink)
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Had my underfloor panel off this afternoon so I could modify my add-on piece making it detachable. Took some shots to better demonstrate what I had done. Here's the factory underfloor panel, passenger side. This is the panel just aft of the front wheel (which would be to the right, just to the right of the notch in the top of the panel:
Here's the panel I made. So it fills in just aft of the front wheel. The design intent on leaving that area free on the production car appears to be related to providing a pad for a car lift to contact. So I've made my panel detachable, with simple push-type body fasteners. I'll just pop them out whenever I go for an oil change.
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11-16-2014, 02:23 PM
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#29 (permalink)
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You do such good work that I'm finding myself wondering what if factory and what it is that you did. ( Great work ! )
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11-17-2014, 05:54 PM
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#30 (permalink)
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wheel cover choice
I'd be leaning in the direction of the black covers.The corrugations of the upper,5-hole covers could have a higher windage drag rotating,in comparison to the smoother,black covers.
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