how bad are big vans are aerodynamically

[racprops]

So been having a big discussion on a couple of Van facebook sites about Big Chevy vans and their aerodynamics.

So I am wondering have anyone done any looks at these vans??

I am talking about G20/30 vans like my 93 and a 2017 Express van.

I am also interested in the Stock and with the great ground effects and raised roof.

Funny thing about my 93 Custom is that the ground effects seem to work, as my Van is NO LONGER pushed around by big rigs, either passing them or being passed by them. A stock body van is buffeted badly but big rigs, nearly pushed off the road…these custom vans (at least mine) are not.

So I wonder how bad these vans are aerodynamically??

And what (IF any) can be done to make a real world improvement.

Rich

jpg.gif IMG_7998.jpg (58.8 KB)

jpg.gif Custom Van.jpg (84.7 KB)

[aerohead]

Originally Posted by racprops

So been having a big discussion on a couple of Van facebook sites about Big Chevy vans and their aerodynamics.

So I am wondering have anyone done any looks at these vans??

I am talking about G20/30 vans like my 93 and a 2017 Express van.

I am also interested in the Stock and with the great ground effects and raised roof.

Funny thing about my 93 Custom is that the ground effects seem to work, as my Van is NO LONGER pushed around by big rigs, either passing them or being passed by them. A stock body van is buffeted badly but big rigs, nearly pushed off the road…these custom vans (at least mine) are not.

So I wonder how bad these vans are aerodynamically??

And what (IF any) can be done to make a real world improvement.

Rich

jpg.gif IMG_7998.jpg (58.8 KB)

jpg.gif Custom Van.jpg (84.7 KB)

I didn't see any data online.
* The Ford van of that time was Cd 0.38. I'd have to see about the frontal area. Guessing around 38-square-feet.Not much you can do about the area.
* Do you drive on the highway a lot, and at relatively high speed?
* Do you plan on keeping the van for a long time?
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GM may have already optimized the grille opening, thermo-clutch cooling fan, leading edge radii, bumper to body sealing, A-pillar radii, airdam. All the 'magic' edges. The mirrors are big, but out of safety, you may want to maintain them as they are. I don't know if an electric cooling fan would save you anything over and above what a clutch-fan is already providing. More efficient lighting would save a small amount of load on the alternator. Messier electric water pump, as on small-block Chevys. Full-synthetic lubes if you didn't already have that. No clue on tires with lower rolling resistance.
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* You might look at some of the belly pans members have done and the issues with exhaust system, mufflers, etc..
A look under a 2021 Van might give you some ideas.
* Wheel covers for alloy wheels is challenging.
* Reducing wheel arch to tire gaps.
* Rear wheel skirts.
* Your rocker panel extensions are good.
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You have an enormous wake.
A receiver-hitch-mounted cargo carrier could support a homemade boat-tail, like, but better than what NASA did in 1980 on their Ford Econoline.
An awning company could heli-arc an aluminum spaceframe and cover it with standard awning fabric to create a very light and strong tail.
Or on a swing-away mount, like JEEP Wranglers use for their spare tires, would give easy access to the rear doors of the van.
Tails by themselves can offer 4-mpg.
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BamZipPow's one-wheel boat-tail trailer is another option. It allows even more boat-tailing, and you get extra storage capacity to boot!
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You've got options.

[freebeard]

So I am wondering have anyone done any looks at these vans??

aerohead is modest, else his memory is gone. Eleven years ago: ecomodder.com: Phil Knox's aero-modded 1970 VW van

Somewhere in this search — ecomodder.com/forum/google_search_results.php?q=van+aerodynamic — is the thread where I posted this:



The major features are bell-mouthed external radiator duct, forward reaching rearview mirrors, Turnpike Cruiser-style fender skirts, and annular wickerbill at the separation point.



My VW panel van: front fenders skirts and a boat tail.

[racprops]

I am considering a few of these ideas, plexiglass covers for the head lights, possible some covers for the front grill, and fender skirts for rear wheels.

As the problem is the void created by its passing though the air I wonder is a trick on old station wagons might help, this is where they put a deflector to catch and put air across the rear window to help keep keep it clear. In other words fill the void.

I am thinking across the back of the roof and on both sides...the question would be how big should these be and what bend to be used and lastly how much would such devices work or worst become more like air brakes??

[racprops]

There is a major question: How much improvement has all these areo changes given a car or van??

Rich

[freebeard]

Those station wagon deflectors redirect a jet of air across the window, but that doesn't magically snip off the wake. The current thinking is Faschenfeld tearing edges (newer Prius) or vortex generators.

Car or van? That's a broad category. It's easier to go from 0.40 to 0.30 than from 0.30 to 020. IOW starting condition can vary.

You want a guaranteed improvement? Chop the top.

[aerohead]

Originally Posted by racprops

I am considering a few of these ideas, plexiglass covers for the head lights, possible some covers for the front grill, and fender skirts for rear wheels.

As the problem is the void created by its passing though the air I wonder is a trick on old station wagons might help, this is where they put a deflector to catch and put air across the rear window to help keep keep it clear. In other words fill the void.

I am thinking across the back of the roof and on both sides...the question would be how big should these be and what bend to be used and lastly how much would such devices work or worst become more like air brakes??

You might want to check out rocketail.com.
My opinion is that it's a scam. Just an opinion, after studying their testing and claims.

[freebeard]

aerohead isn't a big fan of links. Technology – Rocketail



This is more plausible than the station wagon deflector. The multi-element design is similar to F1 front wings.

Compare with a 'tearing edge' or a boxed cavity. ....or slotted tail fins (Bertone BAT and (Jaray?)).

[aerohead]

Originally Posted by racprops

There is a major question: How much improvement has all these areo changes given a car or van??

Rich

* NASA took a circa 1977 Ford Econoline, of approx. Cd 0.50, and got it as low as Cd 0.238.
* I modified my 1970 VW Transporter, and went from Cd 0.43, down to an estimated Cd 0.331.
* The Toyota T-100 went from Cd 0.5016, to as low as Cd 0.195, depending on configuration.

[racprops]

First need more info on Rockettail

Second my van already has vortex generators.

Third ground effects.

So bottom line how much MPG improvements can these aero mods give, in a percentage of MPG improvement.

Rich..

Here are few pictures of my van: