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mwilliamshs · 04-11-2015, 07:34 AM

Thanks for the info.

Here's a shot of MY van. As you can see the fiberglass top adds about 4" of height but's flat on top (has ridges just like a truck bed but is level side to side and front to back other than that). I think that makes my point of "maximum camber" the upper rear corner right?

Here's an idea of what I'm contemplating up front but think a curved air dam, from flush with the front bumper's foremost bottom edge at the center to flush with the inner fenders at the rear, and reaching from 1-2" inboard of the tire's outer edge on each side would be a better bet. I'll likely extend it an inch or so below the lowest point of the suspension which is quite low on the twin I-beam Ford suspension but thankfully my front overhang (from tire to bumper) is very short so the reduced ground clearance shouldn't matter much and it will likely still be 4-5".

Here you can see the minimal OE air dam. It's cut about 2" short on each side of reaching the tires at all, much less their outer edges. I think keeping the width about 2" narrower than the overall tire width (passenger outside to driver outside) should cut down drag without adding to wake. I can't decide if curved or straight would be better. I'd normally think curved but with such a square front-end there may be more to it...?

I used the aero&rolling resistance calculator. Tell me what you think of my inputs and the output. 5000 lbs is a rough guess at this point but not too far off I'm afraid as shipping weight for this guy is 4300 or so and the top adds a couple hundred and the interior has some insulation and paneling added. I modified the Cd from .48 due to the top and lowered both the engine efficiency and drivetrain efficiency due to the truck-like components here. Big heavy C6 automatic chief among them. Rolling resistance is due to heavy load range E tires (not in pics, appointment for installation is Thursday) that I did actually choose for their efficient design and the fact that I'm a religious pressure-checker.

04-11-2015, 07:34 AM	#14 (permalink)
mwilliamshs EcoModding Apprentice Join Date: Apr 2015 Location: USA Posts: 148 VanDelay - '89 Ford Econoline E-150 XL 90 day: 15.93 mpg (US) Old White Civic - '98 Honda Civic LX, AT 90 day: 33.18 mpg (US) Thanks: 5 Thanked 50 Times in 43 Posts	Thanks for the info. Here's a shot of MY van. As you can see the fiberglass top adds about 4" of height but's flat on top (has ridges just like a truck bed but is level side to side and front to back other than that). I think that makes my point of "maximum camber" the upper rear corner right? Here's an idea of what I'm contemplating up front but think a curved air dam, from flush with the front bumper's foremost bottom edge at the center to flush with the inner fenders at the rear, and reaching from 1-2" inboard of the tire's outer edge on each side would be a better bet. I'll likely extend it an inch or so below the lowest point of the suspension which is quite low on the twin I-beam Ford suspension but thankfully my front overhang (from tire to bumper) is very short so the reduced ground clearance shouldn't matter much and it will likely still be 4-5". Here you can see the minimal OE air dam. It's cut about 2" short on each side of reaching the tires at all, much less their outer edges. I think keeping the width about 2" narrower than the overall tire width (passenger outside to driver outside) should cut down drag without adding to wake. I can't decide if curved or straight would be better. I'd normally think curved but with such a square front-end there may be more to it...? I used the aero&rolling resistance calculator. Tell me what you think of my inputs and the output. 5000 lbs is a rough guess at this point but not too far off I'm afraid as shipping weight for this guy is 4300 or so and the top adds a couple hundred and the interior has some insulation and paneling added. I modified the Cd from .48 due to the top and lowered both the engine efficiency and drivetrain efficiency due to the truck-like components here. Big heavy C6 automatic chief among them. Rolling resistance is due to heavy load range E tires (not in pics, appointment for installation is Thursday) that I did actually choose for their efficient design and the fact that I'm a religious pressure-checker. Last edited by mwilliamshs; 04-11-2015 at 09:37 AM..