Meet Grumpy the Rally Van
 

Grumpy is my '97 Astro the I purchased for the sole purpose of entering the 2008 BA/BE Rally, which is a four day road rally from New York to New Orleans in which all vehicles entered must be bought for $250 or less.

https://www.fuelly.com/attachments/fo...47dcc109ed.jpg

Currently with my daily running about it gets about 16 mpg and with a 3000 mile road trip in its future I'd like to increase that. I'm looking into an air dam, blocking off the lower portion of the grill, and either adding Plexiglas over the headlights or switching to composite headlight like on my '99 Astro.

Any other aero ideas for such a rolling brick?

I'm just envious of the $250!

How many miles?

More air in the tires, vortex generators for the rear, and a belly pan?

Ah, I see...

LOTS of miles...

I just started an engine treatment with Auto RX

I've got 250k on my E350, so if I can just gain mileage by cleaning up the motor with the Auto RX stuff, I'd be ahead.

I need driving time on that, and I'll get that starting in a couple weeks.

I did put a small amount in our Focus (a couple ounces), just turned over 100k, and I honestly think that it cleaned some of the deposits that I normally see inside the valve cover.

Might be worth an experiement.

Go wild, man! Build a "basjoos" tail piece.

On a $250 vehicle what do you have to lose?

Wow, Big Dave. Your truck is the reason I found this site. Been reading Diesel Power since the 1st issue.

I can't really see doing a boat tail. I really like using my back doors. The fact that the keys I have don't unlock any of the doors and usually enter through an unlocked back door might have something to do with that.

How much air? What will it do to wear?

Would a belly pan be better than an air dam?

I'd block the upper portion of the grill. It'll reduce drag better than blocking the lower part.

Air up the tires to the max pressure on the tire's sidewall if the tires appear to be in good condition. Check them closely, you never know with a van that cheap?
If you don't plan to carry much weight in it, try lowering it an inch or so. How much travel can the van stand to loose without hurting the ride?
Remove the side mirror. It has plenty of windows and visibility looks good.
Since it's almost the same color as cardboard, just tape on some sideskirts to cover the rear wheels.
Does the bottom of the rear bumper hang down in the airstream? You might want to get a jack and bend it up a little. Don't bend it so high it blocks the rear doors. :)

Upper grill portion, check.

Tires are great actually, PO installed them last year. I currently have them set at 35 psi checking pressure every Saturday.

Lowering would probably be a bit cost prohibitive, that and after the rally I'm thinking about giving it a mild lift and going off roading. Need to chase my wife around in her Jeep Liberty, plus I just like the perceived wrongness of it.

I'll fold the mirrors down for interstate running, but I like to have them in urban areas.

I'll try the skirts, but Grumpy will not be brown come rally time.
https://www.fuelly.com/attachments/fo...04558a04db.jpg

Hmmm, Plexi skirts maybe, allow the wheels to be seen.

Luckily, the bumper does not hang below the body, rear doors barely clear it stock.

Oh, I should probably mention I'm on a very tight budget.

Example:
Grumpy has a weak fuel pump and requires the use of starting fluid to get going. Trying to accelerate in a hurry to merge with interstate traffic can result in the engine being starved for fuel if I hit the gas too hard. Fuel pumps for newer Astros are sold as complete fuel pump assembly units, cost more than the purchase price of the van, and thus are outside of my budget. I found someone on eBay selling generic kits to rebuild it for $30. Placing my order for scary parts today.

Just had the realization that switching to composite headlights would require swapping out the entire grill (definitely beyond budget), going for the Plexi there. Any tips on bending it?

Heating it gently should work, but it turns to gloop at 250C so don't overdo it.

There is a thread here comparing belly pans and air dams. The dams work better. You could also put skirt along the running boards along with the dam. I was looking at some large SUV floor mats at a discount store, they should work for the skirts. Probably too flexible for the dam, or try the plastic garden edging. The dam and skirts would give you the benefit of lowering to the air flow.
Maybe you can mount a kamback directly to the rear doors. Otherwise vortex generators.

I'm thinking homemade vortex generators. I have a couple non-operational TVs that could donate their cases. Where to locate them? I've read where people have them about 3" from the back edge on their wagons. Will my van be about the same?

If you've got a large dead TV, you might wanna see if the rear casing can be used as a grille blocker/nosecone. (Cut a 4-6 inch wedge off the top and stand it on the bumper...) typical TV vent sizes should aerodynamically block at highway speed.

I'm beginning to realise that modding minivans is a balance between reducing base drag and causing higher induced drag. At the moment the lift force generated by the van is probably perpendicular to a line drawn between the bottom of the front bumper and the top back corner of the tailgate. Now, adding turbulators to the roof will probably make the air "tuck in" a bit behind the van... but it will have altered the effective angle of attack, such that the lift vector is going to be perpendicular to a line from the front of the hood to the top back corner.. hence less forward component to the lift.... you can see that if you do a fully faired back on the vehicle, it may alter this line such that the lift force is exactly vertical, or even negative. This is why current cars are going for a clean edge separation higher up the rear of the car...

However putting vortex gens on the sides may have more benefit, since the top down profile of the vehicle is fairly square so there is minimal lift components to the sides to alter for the worse. At this point in time my thinking is that they could be dual purpose, encouraging upwash of the airflow across the sides of the vehicle to help the apparent angle of attack. Therefore I'd suggest delta shaped vortex generators be placed on the sides angled parallel to the line between front bumper and back corner... Also rear underbody treatment should be arranged to compliment this and angle air upward behind vehicle...

Astro fanatic says, "My van aint mini!"

I'm such a noob, had to read through that many times.

So my current lift force is probably ok. Is there a way for me to check that? I'm thinking about making a few wool-tuft runs, will that show me?

How would I go about the rear underbody treatment?

Wool tufts will show you where you're getting separation and turbulence and the direction of flow on various surfaces, but it won't really tell you much about the angles for induced drag.

I have spent some time burning brain cells on the problems of vans. Vans are useful vehicles for certain missions but their truncated tails leave them with an enormous wake area. Grumpy could be the pioneer into the 'land of basjoos' for vans.

Imagine this: A fiberglass boattail attached to the back of the van. It could be either one piece, hinged at the top and raised by electric actuators, or a two piece split along the long axis and opened manually and laterally. How good a boattail it is depends on your tolerance for vehicle length. In both cases, the key is a set of strong hinges with very solid anchor points.

Because properly boattailling a 79 inch wide vehicle would require a minimum 72 inch long tail, you would probably want to truncate the boat tail at some point. Enter Dr. Kamm. The max angle before flow separation is about 29 degrees and the tangent of that angle is 0.554. 40 (half the width) divided by 0.554 is 72 and change. A six foot tail.

If you have done any fabricating you will come to appreciate 25 degrees which is a 6:12 pitch. Easy to lay out. Now your theoretical tail lengthens out to 80 inches ? as long as my pickup bed.

But if you truncated at 24 inches your wake area would be reduced by 54% and now would be roughly that of my faired pickup truck.

Nice thing about Grumpy is that you could weld on hinges and experiment with angles and find out just how much of a tail you can live with.

Basjoos started with a relatively small car and could go for a relatively pure boattail and still wind up with a reasonable-sized vehicle. With an 80 inch long tail, Grumpy would look like a brontosaurus. But I think you could find a happy medium somewhere in there.

Wow - good luck in the run to Big Easy!

Definitely a basjoos-style front end would be the best front you could do. But it would be pretty big.
General wisdom is that on a square-backed beast (mine is a wagon) the aero losses at the rear are more significant than the other aero losses. So, if you have the nerve to build a good boattail that will probably help a LOT.
Pics of my pipedream boattail, which I'll likely never build.
https://i188.photobucket.com/albums/z...earView400.jpg
https://i188.photobucket.com/albums/z...ideView400.jpg

See the pic of my front grill panel to the left of this post.
It replaces all the headlight trim and the radiator grill.

Just recently I made a new one with Lexan (like plexiglass but hopefully more durable) covers over the headlight cutouts. Sorry, no pics yet - my camera went AWOL. It also has a simple rectangular cutout for radiator, with a center post. I have strips of different widths that I can slip in to block off part of the center opening. They press against the center post and at the sides, no fasteners needed. I use the biggest blocking strip that doesn't overheat the system.

Main panel attaches with four screws, one at each corner. It's cut oversize so it bows into shape when attached. Overall shape of panel is very similar to a windshield. It's a section of a cone. Mine is 2.7 mm. lauan plywood. Oil base house primer, then Duplicolor pickup bed liner over that, black textured stuff. The bed liner is very tough. Regular spray-can finish color didn't hold up.

Keep in mind going over a vehicle's size dimensions can have insurance consequences depending on your agency.

I'd add a homemade air intake (cone filter will run about $30 or so, plus another $15-20 in home depot pipe parts and clamps), and synthetic oil with new spark plugs. Total cost shouldn't be more than $115 and a few hours of your time.

Speed is the main killer of mpg, keep it at or under 65mph and you'll get at, if not above 16mpg for sure.

Is this an off road rally? If not perhaps lock the center differential and drop out the extra driveshaft, differential, and axles. Definetly smooth up underside flow haha.

Insurance is cheap, it insures and plates as a passenger car.

The air intake mod you describe has been reported to decrease mpg when done inside the cramped and hot engine compartment of the Astro. On my good Astro I installed a K&N filter than changed the intake routing to the drivers side drawing cold air from behind the left hand turn signal. Seems to work pretty good, but I have some off road plans from Grumpy after the rally and want to keep the intake in a higher location. Maybe I'l try to figure out some cowl induction.

I've been mostly keeping to 65 or under for my regular driving. I'm already able to get 16 mph pretty regularly. I'm working on my semi drafting technique. My current goal is mpg.

This is kind of a gimmick rally, speed is not important, but matching photos, spotting plates, and other various tasks to gain points is.

I would strip out the entire interior if you don't have to haul any people to save on a lot of weight. Heck it problably has 2 captains chairs and a 3rd row bench.

So you problably would save 150lbs or so. Even the sound proofing under the carpet is heavy. Save about 200lbs off the total of the van it will help out a lot.

So how has the project worked out? Have you done any mods to it yet??

So, the way I undertand it from what I have been readin the boat tail works by extending the length of the vehicle and allowing the air to stick to the body longer. Now, if the concept still works when drafting, that means that there can be a gap and the concept still works. In this case, it might be worth it to invest in modding a trailer instead, since you want access to your back doors.

Has anyone considered putting the boat tail on a trailer or at least on a trailer hitch mount? That means it is detachable and you can still reap the rewards.

I'm just thinking out loud and apologize in advance if I said something dumb. :)

That could work, but you'd gain a minimum of a couple of hundred pounds of extra weight to lug around and the extra rolling resistance of two more wheels. So on long highway hauls it would probably show benefits, but less so on shorter hauls and probably would lose MPG in mixed driving.

Right. The enemy is weight but if all you have is the wheels and the frame and you're not carrying any load, other than a massive Styrofoam structure (you do need some weight or this thing may go flying. :) ) then it might pay off. Of course the payoff would come in longer stretches of steady, moderate speed, possibly drafting a much larger vehicle.

It would look something like...
https://img170.imageshack.us/img170/8...tailnj0.th.jpg

Make it so it plugs in to a trailer hitch receiver. Make it a tapered box, or even a box somewhat smaller than the rest of the van but not tapered.

If you made it from foam sheets and covered it with some kind of skin it could be both light and strong.

Grumpy has sat on the side for a few weeks. Last weekend it started for the first time with the new $30 fuel pump. I decided to withdraw from the BA/BE Rally this year, due to lack of team members and paying for my Husky's heart worm treatment. 2009 currently looks good, so I have a long time to prep. In the meantime, I'll use Grumpy in various local events and hand out fliers to find team members. I'm going to finish bringing the mechanicals up to par before I really try work on any aero stuff, but the boat tail plates from the semi trailer post look promising.

Thanks for translating from english to english. I think you're talking about the square thingamajiggy that the actual trailer hitch attaches to. If so, that's what I meant to say.

English as a third language can be a problem once in a while. :)

Actually, if it turns out to be as effective as I think it may be, this trailer hitch or small trailer aero extension is something that probably can be marketed for the boxier vehicles. A couple of steps short of the full body aero additions proposed on another thread, but probably more practical and less expensive.