Quote:
Originally Posted by ShadeTreeMech
From what I'm reading, .35 is very low for such a large vehicle. I'm wondering if the weight of the vehicle (nearly 2 tons) isn't partly to blame. The engine is a fairly old design (it still has a distributor and 2 valves/cyl.) and it revs fairly high in overdrive. It spins about 2400 rpms at 65 mph. But the engine size is quite small @ only 3 liters. I might have some tuning issues, and there is a dragging brake caliper, but I'm averaging 22 mpg, in mixed driving, which is close to the EPA est for highway driving. I'm thinking maybe some of those new iridium spark plugs might help. They sure did wonderful things for my friend's truck. A warm air intake would be fairly simple to pull off, but my van tends to octane knock awful easy as it is.
My wife and I only accelerate heavy when necessary, otherwise we keep the rpms under 2800 or so. I'm trying to remember if advancing or retarding the timing helps low end torque....
Either way, we live in the Ozarks, which is quite hilly. There are a few places we can put the car in neutral and coast at speed from gravity.
Before I drop the aero ideas, would a belly pan help much, or should I just shackle up the rear a bit?
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The 1922 Klemperer"minivan" achieved Cd 0.16,something which would push your mpg to 27.5 mpg on the highway if your getting 22 now.It's rather amorphous in appearance,with windshield hard to distinguish from rest of forebody.The shape is proven although requires everything from the B-pillar rear to converge along the ideal teardrop taper path.Pretty radical.Short of that though,it's difficult to achieve any dramatic drag reduction without lengthening the van.Virtually all your drag is behind the van in the wake.At one time,Chrysler advocated a vehicle with inter-changeable roof sections.This would have helped out,as a fast-back style roof would have allowed for significant drag reduction,albeit ,with some sacrifice to interior volume.Parking issues make a boattail extension problematic for daily driving on vehicles with significant rear overhang.