I have been reading and posting on a forum addressing improving the economy of all cars. They actually have been quite welcoming of my questions about the Dart, and have offered good suggestions, all of which honor the appearance of this classic. The most recent was to fill in the hole in the bumper where the inter-cooler once was. While this will not make a huge improvement, it will make some. Guys on the ecommoder forum research this kind of change all the time in their quest for small improvements. Each little change adds a small amount of improvement which in their totality amount to something. I guess you could call in salvation by a thousand band aids.

Anyway, this week I filled in the hole in the bumper. It seems that if you can keep all air that is NOT needed to keep the engine cool, out of the engine bay this reduces drag by quite a bit. Even though the nose on these old cars is pretty blunt, it is better to push the air down the road than to let it get under the hood. Of course you have to monitor the temp to make sure you have not blocked things off too far. Here is the look of the car after blocking the hole off and raising the license plate.



While it is not obvious, there is a fair amount of rust through from behind on this bumper. I will eventually replace it with a new, re-pop one.

Sam

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what is the spoiler off of?

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1980 Aspen 4 speed

That is a standard Chevy pick up truck from the late 80's into the 90's. They are everywhere. I had to narrow it. I used the section cut out of the center as a splice behind it. The small Chevy truck for the same period looks similar but is smaller. You could look into that and see if maybe it did not need narrowing.

Today I blocked off the right side of the grill. Here is a photo of that effort. I put black painted aluminum behind the grill. You cannot tell it is there from normal viewing angles.

Here is the breakdown on where the drag comes from on autos:

30%, the body, 30% the underside of the car, 30 percent the air through the radiator. If you have a good radiator, and a good fan, you do not have to push all the frontal air through the radiator at speed. So blocking part of it off cuts down the through-the-radiator drag. Reducing the drag allows the engine to work in the higher vacuum range of the fuel management, whether carbureted or fuel injected. This results in less fuel use.

Sam



Driver's side of grill blocked off from behind.

Sam

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Have you thought about full "smoothie" style hubcaps? Lots of the hypermiler guys run them, and if you look at the old Honda insight they use a similar design,also some Prius' too. Keep up the good work

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Looking for a 70 Dart Custom 4 Door.

I saw a set of that style "moon" caps on an 18 wheeler, today. All wheels except the "steer" wheels.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Yep I forgot the long haul guys use 'em too. Can't run em on the front because of the hubs/brake cooling.

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Looking for a 70 Dart Custom 4 Door.

Did you move the inter-cooler, or are you no longer running one?

p.s. I enjoy following your aero improvements. So far I've only done an air dam on mine (Ford Ranger, like what you used to run), but plan to do more. So it's nice to see you post pictures of ideas I have floating around in my head!

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Intercooler and turbo are gone. The project is now focused on keeping "the look" while maximizing gas mileage. All the mods must be stealth, and minimally invasive to the stock appearance. My first goal is to work it until it gets over 30 MPG on the highway.

The combination of my ignition and the turbo never worked together well. After five years of fussing with it, I took it off. This allowed smaller injectors, which are much more efficient at idle. It used to idle at 1.9 ms with 36lb injectors. Now it idles at 1.6 ms with 24 lb injectors. I don't understand that, but that is what happened. Maybe the smaller ones have a finer spray and atomize better.

Yes, the moon pie, or pizza pie hub caps are the thing for gas mileage. At this point I am too attached to the stock look. I think I may eventually take that leap when I have run out of other things to do. Faring in the space between the wheels on the side is another excellent mod, but again it would not look stock.

The undersides of these cars is a gold mine of improvement, and that can be done without changing the look. Once I am through with the front end, I will head back down there. I am still researching how to smooth out the undersides of a car that has a live rear axle and a drive shaft. The very best car ever in this regard was the old VW beetle. With the engine at the rear, not exhaust pipes, rear pumpkins or drive shafts to work around. The bottom was absolutely flat. Thanks for your input. Any ideas offered will be gladly absorbed and will "float around in my head" to quote Zorg.

Sam

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Thanks for your updates and musing, Sam. Did you just quote Zorg from "The 5th Element?" One of my all time favorites. Or, maybe you mean Zorg on this site...

Keep in mind that you will often run into a "limiting factor" that can dwarf all other mods. I am sure you know this, but just responding to your "30, 30, 30%" comment. One example is that I lowered my airdam by 3-4" on the 68 Dart and it made almost no difference in mileage. At this point, I believe the rear window and high 4dr roofline are limiting me. Of course, I will try some new things besides chopping/angling the top to test that hypothesis!

"Time is not important. Only life is important."

Lou

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Home of Slant6-powered fun machines since 1988

Air Tabs on the back of the roof and the back of the trunk lid. They would disrupt the total stock look, but would be fairly unobtrusive.

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Casually looking for a Clifford hyperpak intake for cheap.

For driveshaft and rear axle, I'm thinking something like this.




A slot in the belly pan for the driveshaft.

The belly pan ends just before the axle and just below it at normal ride height. You could have a smooth bubble for the pumpkin that does the same thing,

After the axle you have the belly begin again (slightly higher than the front section) with a rounded leading edge.


You could attach a smooth bubble like structure to the pumpkin so that where it's in airflow it's smooth.


Attach something to the axle so it's in an airfoil/teardrop shape (making the rear section of belly pan after axle less critical)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Sam, and others
nice work, this article has some nice tips

http://www.hotrod.com/techarticles/body ... ewall.html

I saw another internet article where they spoke of taping 6 inch ribbons in multiple rows across the hood, roof and rear deck, bumpers,,, then driving at highway speed while a second car's passenger video'd the direction and flow of the ribbons,,,

you would be looking for the ribbons to flow smoothly back and not whirl around or change directions.

Thanks Dad. I love writing that! That was an interesting article.

Reed, here is a write up of the "wing" design and how it came to be.

http://en.wikipedia.org/wiki/Kammback

If there is a way to incorporate a subtle version of this on the rear deck it is probably a worthwhile thing.

The rear presents the challenge of getting the air back together gracefully. The are two basic approaches: One is to taper the rear so the air flows back together without separating from the body of the car. That would be pretty hard to do with the box of a Dart. However number two is to get the air to separate complete and abruptly with the attached spoiler. This is common on many cars today, and the Dart shape is appropriate for that approach. .

This is what Reed was addressing. If I can find a stock one that is flexible enough to conform to the minimal curve in the Dart's trunk I might spring for that. Two or three models from the 80s had ones that look like rubber and looked removable. I am thinking of the BMW 6 series, the Saab 900 and a few Mercedes. I am sure there are others, as well as aftermarket "gee-whiz-I'm-a-racer ones.

Then comes the problem of attaching it. Do I drill holes in a good rear deck lid? Or, is there an adhesive that will hold. Some of the cheezy after-market hood scoops come with double sided tape.

Lou, I think you are right. The 20-80 rule definitely comes into play here. It may be more like 10-90. The initial big improvements are pretty easy, and then you have work hard to make little incremental improvements. That rear roof line is a challenge. A kamm-back lip going back from the roof, over the back window would absolutely yield bid improvements, but I don't have the guts to take that plunge at this point. Look at the back of the Dodge station wagon the produced about 10 years ago now. I do not remember its name. It was a Charger station wagon. Also, look at the rear of every Lexus SUV.

Ed thanks for your ideas. I am still stewing over this one. There are many terrible turbulence producing things that stick down under these cars, but the added air dam makes these less a problem. I think my first project is going to be to fair in the wheel wells on the INSIDE of the wheel. leaving these open as they are produces lots of turbulence and disrupts the flow of the air under the car when it gets to the back wheel.

Thanks for reading this "blog" . You guys are still a valuable source of creative thinking and inspiration.

Sam

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After finishing the grill block off on the passenger's side, I drove the car 100 miles watching the temperature. It hit a low of 175 and a high of 200. There is certainly enough air flow.

I also removed the huge mud flaps and put smaller ones on. This, at the urging of the Ecomodder forum guys.

This business of blocking the grill off also seems to speed up warmup. Another thing I am going to look into is closable louvers for the remaining openning such as the new Ram trucks have.

Sam

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Yes, i think i would stay with the stock hubs too...They look nice!

What motor are you running? It would be nice to see some pics of it

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1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission