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Snowman9000 · 11-19-2014, 08:37 PM

[quote] Top picture, the Chevy chassis, is exactly what you have? Looks like there is already a pretty good airdam there.

What was the old motorhome? What are the two engines and transmissions? You should plug both of them into the Aerodynamic & rolling resistance, power & fuel consumption calculator, in the Tools section, and see if the differences agree with your observed MPG. You could then tweak your current setup in the tool and see what gains you can make. [\quote]

Yes, the Chevy. There is just a short rubber flap there now. I measured things today. The bottom of the bumper is 14" off the ground. The front crossmember is 8.5" off. There are plenty of mounting holes in the bottom of the bumper. But I'd need something 6" tall, plus a mounting flange or a piece of aluminum angle or something like that. A 6" dam would not scrape on 15º grades.

My old motorhome was what is called a B+, rather than a Class C like my current one. The B+ does not have a sleeping bunk over the cab. Instead it has a slimmer, much more aero protruding cap up there. Both have 6.0L gas engines. The older one had a 5 speed with one OD. This one has a 6 speed with 2 OD ratios. I think if the older one had had a 6 speed, it would have done real well. It was closer to the ground, and lower in height than my new one.

Old one looked like this (not mine):

11-19-2014, 08:37 PM	#13 (permalink)
Snowman9000 EcoModding Lurker Join Date: Jan 2011 Location: Illinois Posts: 35 Thanks: 3 Thanked 8 Times in 6 Posts	[quote] Top picture, the Chevy chassis, is exactly what you have? Looks like there is already a pretty good airdam there. What was the old motorhome? What are the two engines and transmissions? You should plug both of them into the Aerodynamic & rolling resistance, power & fuel consumption calculator, in the Tools section, and see if the differences agree with your observed MPG. You could then tweak your current setup in the tool and see what gains you can make. [\quote] Yes, the Chevy. There is just a short rubber flap there now. I measured things today. The bottom of the bumper is 14" off the ground. The front crossmember is 8.5" off. There are plenty of mounting holes in the bottom of the bumper. But I'd need something 6" tall, plus a mounting flange or a piece of aluminum angle or something like that. A 6" dam would not scrape on 15º grades. My old motorhome was what is called a B+, rather than a Class C like my current one. The B+ does not have a sleeping bunk over the cab. Instead it has a slimmer, much more aero protruding cap up there. Both have 6.0L gas engines. The older one had a 5 speed with one OD. This one has a 6 speed with 2 OD ratios. I think if the older one had had a 6 speed, it would have done real well. It was closer to the ground, and lower in height than my new one. Old one looked like this (not mine): Last edited by Snowman9000; 11-19-2014 at 08:46 PM..