Snugtop Increases MPG?

[JohnLindholm]

I put a Snugtop on the Av in 10/02 and since then my MPG has improved! We drove to Myrtle Beach for Easter vacation, and with 4 people and a FULL bed, I averaged right at 19 MPG. This was mostly cruising at 70-75 mph on the various interstates. It seems counterintuitive that adding the weight of the Snugtop would actually help the MPG, but I think it might have to do with the new shape of the rear end. Drag comes not only from the air resistance at the front of the truck, but also from the low-pressure zone creatd at the rear. That lowered air pressure tends to "pull" back at the Av. My guess is that the standard configuration, with it's wide, flat rear window set at the end of the "tunnel" created by the sail panels creates a strong low-pressure area that is dififcult to dissipate. The Snugtop, on the other hand, "smooths" the shape of the truck and not only lessens the drag by creating less low-pressure at the rear of the truck, but allows it to dissipate more quickly in the slipstream. You have a slightly tapered shape at the rear, instead of a flat and recessed area behind the cab. All I need is an Av-sized wind tunnel. Any thoughts? (Next: "Does Zaino's decrease boundary-layer turbulence?")

 

[sjudson]

I did not not loose or gain on mileage but the wt. does make it handle better and lowers rear end a bit so AV is closer to level

 

[mcrendog]

I put a Snugtop on the Av in 10/02 and since then my MPG has improved! ?We drove to Myrtle Beach for Easter vacation, and with 4 people and a FULL bed, I averaged right at 19 MPG. ?This was mostly cruising at 70-75 mph on the various interstates. ?It seems counterintuitive that adding the weight of the Snugtop would actually help the MPG, but I think it might have to do with the new shape of the rear end. ?Drag comes not only from the air resistance at the front of the truck, but also from the low-pressure zone creatd at the rear. ?That lowered air pressure tends to "pull" ?back at the Av. ?My guess is that the standard configuration, with it's wide, flat rear window set at the end of the "tunnel" created by the sail panels creates a strong low-pressure area that is dififcult to dissipate. ?The Snugtop, on the other hand, "smooths" the shape of the truck and not only lessens the drag by creating less low-pressure at the rear of the truck, but allows it to dissipate more quickly in the slipstream. ?You have a slightly tapered shape at the rear, instead of a flat and recessed area behind the cab. ?All I need is an Av-sized wind tunnel. ?Any thoughts? ?(Next: ?"Does Zaino's decrease boundary-layer turbulence?")

boundary-layer turbulence? Wow...must be a mechanical engineer talking. I'm not a fluids guy but I'd guess that it would decrease drag. Now ask my a question about controls and maybe you can get an educated answer.