Aeromodding the Astro Van
 

Hello hello! I'm am about to have a large undertaking.. taking a 94 Chevy Astro van w/ 4.3L i6 engine powering an automatic all wheel drive train and turning it into a 30mpg+ hwy van.

I need to make a 33% increase!!

I'm starting with the basic weight reductions and air dams for the front and rear wheels.. maybe the front if I can do so safely. Also as always, plugs, wires, filters and cheap sensors.

I need ideas or success stories with monsters like these! I'm trying to not break the bank here, anything will be considered. No boat tails though, its already almost 13ft of truck like van, I cant add another 8ft for the tail hahah

http://images.craigslist.org/00y0y_i...L0_600x450.jpg
http://images.craigslist.org/00x0x_d...bO_600x450.jpg
http://images.craigslist.org/00y0y_i...NA_600x450.jpg

Whoa, you have an uphill battle ahead of you.

I think at a minimum you will have to disable the AWD, swap to a manual transmission (if not a different engine) and add at least a partial boattail.

I just read an older forum about a gentleman that took his 89 astro and turned it into a 30mpg+ diesel/ stick conversion van. I might not be able to high five a 30mpg tank, but any increase over 20hwy will be awesome. I was also considering a partial kammaback, but the rear window raises on struts, so securing it might be more difficult that I could do working in a simple 'screwdrive and wrench' garage.

BTW I had the 84 mazda b2000 that I was requesting help for a few months back. After removing the bed and custom building a plywood boat tail, I was able to achieve 33mpg over the stock 26 highway. Wish I would have had pics of it, it looks like an aeroplane :(

You asked for aeromods but I think you already know the answers: bug shield delete, mirror delete, roof rack delete just for starters; grille block, skirts, flat hubcaps, air dam, partial/total belly pan, and most importantly by far a tail of some sort.

On this buggy the wipers MAY be in the air stream; can you set them lower (closer to the hood) and/or delete the passenger side arm. Have you driven it in the rain and noticed if the raindrops get blown off the entire windshield, or do they just sit there on the bottom 4-7" like they do on my 3-box cars? No movement there = stagnant air bubble = don't fret about the wipers then.

Are the springs good? Can't tell if the rear of the van is low; on most designs good aero calls for a slight nose down attitude.

I completely forgot about exterior drag xD

Deletion is a must.

So speaking for practicality: I am a safe driver and confident in my abilities to handle the astro with out bumpers, but would a bumper delete also negate the ability to mount the front air dam without drilling 5 holes in the chassis? I might as well go for it.

What are we currently using for bellypans. All I'm seeing in searching it is what it does.. not how to fit or what its made of :/

33%
 

If you did the 33% mpg increase solely through streamlining you'd need a 66% drag reduction.
If you were starting at say,Cd 0.34,then you'd have to go below Cd 0.12.
I think that your windshield is not of sufficient curvature that you could pull off extreme front modifications to get you near Klemperer's 'minivan' of 1922,with Cd 0.16.And it had about 3-feet of boat tail.
A reverse-Template could get you to around Cd 0.142,but you'd never be able to see out of the windshield at the angle it would require.
You might try some extreme cardboard and duct tape mods long enough to see if they 'showed' at the pump.
The 1987 Renault Vesta II was Cd 0.19.
The Mercedes-Benz Boxfish is Cd 0.19.
Both of these would be worth looking at as starting points.
The Pontiac Trans Sport,Cd 0.30 will get Cd 0.12 with a full boat tail.Lay tested 'it' in 1933.It could be inflatable.
My VW Transporter went from 27 mpg,to up to 35 mpg with a full belly pan,rear wheel skirts,steel radial tires and 18-inches of boat tail.
That enormous wake behind the Astro is killing you at the pump.

What are you doing that you need the van for? Towing, hauling, big family?

What kind of driving do you typically do? Short city commute, lots of highway, poor roads/ off road you need awd for at times?

I'm definitely a granny when it comes to driving. We do a lot of travel on and off throughout the year, so the awd is a must for the mountains and the van is a must for comfy sleeping, the roads are always unpredictable but we could safely say smooth roads 90% of the time :)

I've got a 97 AWD cargo. Empty I average 19-20 mpg, but it's never empty anymore, so I'm at 14.5 mpg.

On the Astrosafari forum some have dropped the front drive line, but only reported a 1 maybe 2 mpg increase, their still turning all that gear in the front diff. The only way to truly dump the AWD is to swap to a 2wd sub frame.
The biggest gains we've seen in mpg is a V8 swap, probably 3-5 mpg increase.

There are other ways to make those front wheels freewheel.

hub locks are your friend

There's your challenge, set a barely attainable goal and disallow the one thing that could get you there [on it's own]. 13' doesn't sound that long. My VW Beetle is that long.

My experience averages aerohead's. 30mpg at 55mph in a stock bodied VW panel van.

How to answer the challenge? I would gets chrome exhaust stacks, mid-sized truck parts—maybe 4-6" in diameter. Mounted them at the outer ends of the rear bumper where they thoroughly obscure the stock taillights. Punch a row of louvers [exhausting innies] at about 68° to the centerline. Hook them up to your exhaust system. The big plenum on the end of the exhaust pipe will slow and cool the exhaust and then the small area of the louvers will recompress it so that the Coanda effect pulls the attached flow around the corner to pinch off and detach the low-pressure bubble in the wake.

That and complete bellypan/wheel spats. Extend the front bumper brackets and cut the tips off the bumper. Faired in, it would be just as safe as stock. Most of the bellypans you see here are Coroplast. I like PolyMetal.

OR you could do it *all* in the drivetrain with a 2WD 6-speed turbo-diesel.

13 feet? My Probe was 18' including the 40" boat tail and I drove it on unmaintained dirt logging roads in Michigan's upper peninsula. It was the ground clearance that was the problem- even the overhangs weren't an issue.

With that van you could do a million things to get a couple MPG or you could build a 5' boat tail and be happy. You could even turn the tail into a storage compartment for extra cargo. Use the trailer hitch to help support the thing.

Hey Colton,

Looking at your van, looking in particular at the rear doors, I wonder if you could build a couple of extra clamshells that would close on top of them. The idea is that you could open the extra skins and prop them open like a Trailer Tail, wide enough to get the wake to reattach but still tapering in to reduce the overall wake effect. Another panel at the top would close the top of the wake. The bottom would just have to be the hot mess it is, I guess, unless you're very clever and can come up with a good solution for down there as well. Right now I'm at work and can't devote much thought to it. But looking at actual Trailer Tails that trucking companies are paying good money for, you can see that they don't have to be perfect to be effective and economically worth the trouble. And like a Trailer Tail, when it comes time to park you can just fold them up. So you'd be longer on the road but not in the garage, and it would be a matter of seconds to make the transition.

It wouldn't be the complete, ideal tail that would bring your whole wake to a smooth point, but it would be about 2.5' of taper that could reduce your vacuum wake to a lot less than it currently is. Any improvement on this rolling refrigerator box is, well, an improvement.

But that's a big project. Smaller, quicker and much much easier are rear wheel fender skirts, smoothie wheel discs up front, and a belly pan. To answer your earlier question, plain ol' coroplast gets it done for belly pans, but for a quickie proof of concept project you could put something together with cardboard. Use plenty of supports to keep the cardboard from tearing in the wind, and be advised that one puddle = no more bellypan. And with either coroplast or cardboard, beware the exhaust system. Insulate it, provide ventilation, stay the heck away from it, whatever. But with either material, the high heat could prove very problematic.

The Japanese had a cult following on the GM Astro back in the day, even had an effect in the boxy styling of their Kei-vans.
http://cdn.speedhunters.com/wp-conte...2/02/van25.jpg

...or a kei-'Slade? Styling Effect Consept B :

An 'Murican chop. Astroghini Photo Gallery - Autoblog

Not an aeromod, but near the top of your list with one of these vans should be replacing the belt driven fan with an electric one. The fan from a Ford Taurus is usually the preferred choice.

This is a popular one on these van's. Theres a couple good write up's on it over on the astrosafari forum. I'll see if I can find them and pm you the link's.

post's found, link's pm'd

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A little late to the party here but how much of an increase does this usually provide?

Within some upper limit it will vary depending on driving habits and conditions. Am I leaving anything out? Oh yeah... the vehicle.

Thanks, that narrows things down in a thread specifically about a Chevy Astro.

:rolleyes: