Topic: New to Classic Winnebago

[TSegerson]

Hello One and All,
New owner of a 1983 Winnebago Chieftain. Looking for info on manuals, restoration ideas, and customizing the motorhome. Looking to make a Radical motorhome out of the old beast. Right now working on the brake system. Tom

[Oz]

Hello and welcome!
Would love to hear you plans for a "radical" winnebago.

[c farmer]

Welcome  I have a 1982 Cheftain.  Shes a beast.  Also if you become a paying member it unlocks manuals, and alot of them.

[TSegerson]

I've built radical custom cars, motorcycles, bicycles, etc. I'm looking to streamline my '83 Chieftain and making it more aerodynamic. Am looking into cutting the rear end off and making it a Kamm back. More to follow.

[Oz]

If you want to make it more areodynamic, you'll have to cut off the front end too, lol!  After the last century, designers gave up on that for the front ends.  Notice they have all been flat, square since.  I think the angled fronts of the 1980s is about as aerodynamic as they were made.

[tmsnyder]

1973-1978 GMC motorhomes, the only motorhome built by a major automobile manufacturer, was designed in their wind tunnel to have a low drag coefficient.   Drag coefficient was 0.31 on their model.

Here's a good overview, radical for its day!

http://www.bdub.net/publications/GMC_Motorhome_-_The_Story_of_a_Classic.pdf

[TSegerson]

I'm looking to cut and extend the front end, round it and taper the top over the windshield. Cut the back off and shorten it by about a foot, build the bumper into the rear of the body. The other ideas include a full undertray to clean up the air flow under the body. Goal is to increase fuel mileage and better handling in winds and heavy interstate traffic. More later. Thanks for the comments and input. Tom

[Oz]

That's quite a bit of modification. The frontal aerodynamics don't affect anywhere near as much of the handling characteristics as does the big, long, flat sides. It's the side air blasts which push you around.  Well maintained steering and suspension, as well as air bags do more than anything else.  As for increasing gas mileage, don't be disappointed if you olny gain .01 mpg.  There were several, very aerodynamically designed RVs in the 70s and they got the same mileage as the rolling bricks.

[tmsnyder]

Quite a bit of truth here, I assume you're referring to the 70's GMC motorhome?   I have a 76 and you are right, I'm not seeing the mpg improvement over the big square brick that the aerodynamic shape should deliver.  It's better but not leaps and bounds. 

My Holiday Ramber slope nosed Class A brick gave me 7.6mpg over 19,000 miles.  The GMC is quite a bit smaller so it's punching through a much smaller area and I'm getting 8.5mpg over 1200 miles.   Common thought on these is they give 8-11 mpg.

All of the mpg improvement could be attributed to the smaller size, it doesn't seem like the aerodynamics play much of a role.

It is much easier to drive though and isn't nearly as effected by trucks blowing by.

That's quite a bit of modification. The frontal aerodynamics don't affect anywhere near as much of the handling characteristics as does the big, long, flat sides. It's the side air blasts which push you around.  Well maintained steering and suspension, as well as air bags do more than anything else.  As for increasing gas mileage, don't be disappointed if you olny gain .01 mpg.  There were several, very aerodynamically designed RVs in the 70s and they got the same mileage as the rolling bricks.

[Oz]

Over the years, that's pretty much the observations I gathered from our owners of all kinds of makes, models, and years.  Aside from driving habits, terrain, and mechanical condition, I assume power to weight ratio plays an important role.

[Elandan2]

Don't forget the difference in fuel. Today's gasoline is mixed with 10-15% ethanol reducing the available power (BTU's) in the fuel. In addition, these vehicles engines were not designed to use this type of fuel.

[Oz]

Very good point! I run Lucas ethanol treatment in my old engines.

[c farmer]

Very good point! I run Lucas ethanol treatment in my old engines.

Maybe I should too?   Never thought about it.

[Oz]

It definitely makes a difference in my 95 Chevy truck.

[Oz]

Aerodynamic front end.  Cutting and rounding it.
Here's about as aerodynamic as Winnebago made them.
1987 Elandan.

An add-on downdraft spoiler was also made which simply attached to the top triailing edge of the rear.  Not "radical", like a kammback, but does the same job of eliminating the turbulence which causes the "pull back" effect without having to taper the rear, sacrificing the height of the interior, or extending the body to impractical length.