> You can lower th front and raise the rear
>
>
> >
> >
> > Legitamate ways to reduce drag on a GMC Motorhome.
> >
> > Install a front spoiler or air dam, the largest you can find that will
> > still give you adequate ground clearance. This will reduce airflow under the
> > vehicle which would otherwise swirl around on components that hang down
> > under the vehicle causing drag. Some sort of undertray or belly pan may also
> > help with this problem.
> > Nascar race cars even haved smoothed and boxed lower A arms on there
> > suspension to lower underbody drag.
> >
> > Reducing frontal area of the vehicle would also help, fitting the smallest
> > mirrors you could comfortably see out of and removing all the ladder, A/C
> > roof boxes would also help.
> >
> > Fitting flush wheel covers would work also.
> >
> > Doing all of the above would undoubtedly lower the Cd of the motorhome and
> > give slightly better MPG,but at the expense of Comfort (no roof AC)
> > Convenience (no roof pod) Safety (small mirrors) Ground clearance (spoiler)
> > --
> > 1976 23' GMCII By Explorer
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>
>
>
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk
>
http://www.appliedgmc.com
> 1-800-752-7502
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Hi Jim,
I know lowering the front and raising the rear of a sedan or hatch back has been proven to reduce drag on production based race cars (like mine), but I am unsure how it would pan out on a vehicle with a very long roof like the GMC motorhome.
My own feeling is whilst lowering the front would obviously limit the amount of air passing under the vehicle (lessening drag) the subsiquent raising of the rear as a result would expose more of the roof section increasing the total frontal area increasing drag.
Also I suppose lowering the front would screw up the ground clearance and geometry of the suspension , increasing castor angle (making the steering more resistant to turn when the vehicle is in motion) and increasing negative camber scrubbing the inner edge of the front tyres out prematurely.
I have no idea whether GM actually put a full size GMC motorhome in a wind tunnel, but scale models may have been tested at various points in the vehicles design.
The GMC certainaly has an aerodynamic look about it, so at least creating the impression it slips through the air with ease(compared to other motorhomes of the period) was on the designers minds.
Wayne
--
1976 23' GMCII By Explorer
