Hey - Young vanner here

[johnpr]

just to make my stance clear, im not advocating a 3 in exhaust, DPoV is right, too large of an exhaust will harm performance and eficiancy, and so will an exhaust which is too small, its just one of those if everything else is taken care of then make sure that is in order also.

[MetroMPG]

Maybe you could mod your high top to make it a "pop" top that you can lower while driving.

Decreasing that frontal area would give you a measurable gain at the pumps, and it might not have to cost much money, either.

[Vanner]

Hey! like the others I dont have much time here, but i want to thank you all for the ideas again. a pop top is in my dreams, in the meantime im trying to figure out a way to get the most out of the extra height (storage, dance parties...). if i had a waterbed sitting around i would seriously entertain it. i have. little tacky though.

finally, i am absolutely changing the rear end, but because it means a compromise in acceleration and taller gears are a little more flimsy i'm looking at wheel size and OD gear ratio first. Then final gear to get the engine to the target rpm at 70mph, yes? Whatever that heck that rpm might be.

johnpr, on point with everything as always. thanks again, i love the ideas! i'll have to throw in a picture of the frontal area for some laughs.

[johnpr]

thats great, i didn'e even think about the fact there arent any pix in this thread. looking forward to seeing your ride

[elhigh]

Originally Posted by Vanner

i love the ideas! i'll have to throw in a picture of the frontal area for some laughs.

That's gonna be a big picture.

[Vanner]

For all intents and purposes, it looks like this but white:

[whokilledthejams]

Welcome!

Without too much effort (i.e., getting it in good running order), you should be able to manage upper teens on the highway. My girlfriend's parents have an old GMC conversion van that averaged 18mpg when they drove from NY to Texas last christmas, so low-20s is probably within reach, really.

[Johnny Mullet]

Dude! I love vans! I had a few "Hippy Vans" back in the day. I had a 1973 Dodge Sportsman and a 1993 Chevy similar to yours.

I know you wanna do up the interior, but that will add a lot of weight and sacrifice some MPG's. My 1974 Dodge was a cargo van with no windows (except the small teardrop side windows) and for the interior, I laid plywood, and then that egg foam on top. After that the entire interior got 4" dark blue shag carpet including the ceiling and walls. It was like climbing into a big furry cave. Ahhh, the memories..........

Anyway, welcome to the forum!

[Greenblazer]

Welcome!

Less weight will help, water beds not so much. If there are a bunch of back seats that are rarely used remove them, it will help, and those running board/fender flare thingies don't look very aero, and it might help to remove them too. If the speed limit on the freeway is 70, then get in the right lane and go 65 or even 60 it will make a really big difference. Speeds over 60MPH really start sucking gas.

Later,

Allan Greenblazer

[Vanner]

I forgot how much fun it is on this forum!... and looking back everyone had some excellent ideas on economy. Mullet, that is what i ended up doing with the floor, but rubber-backed indoor/outdoor carpet instead of shag, and indeed that was the gist of the original flooring by the conversion company. Killingjams, I've had other people cite that exact number. That tells me that 18mpg is the glass ceiling for the 305. Not my 305, im using seals that were supposed to be replaced 100,000 miles ago. Increasing beyond 18 will likely involve either running a smaller engine and some clever gearing, or a smaller throttle body, new seals, and some clever gearing. Either way reducing power in some way other than throttle plate restriction.

The points of resistance I encounter from other people: in the case of an engine swap, a general adversion to running an engine (even a smaller one) at higher rpms, which people universally explain as "the engine has to work harder." Every engine has it's "sweet spot" and running it faster than that will decrease efficiency, but by how much? Enough to be outweighed by the fuel economy benefit of smaller displacement? In the other solution, of a smaller throttle body (the van is TBI), the AmeriV8 crowd pans the 305. If it is inferior to the 350 in every way, why is it in my van? Either way, I've never seen a larger-displacement engine get better economy than a smaller one. Ever.

Rambling. My plan is to figure out how much torque I need to keep this van moving at 70 mph, and then go to GM and other manufacturers and get this magical graph im pretty sure doesnt exist called "torque vs. fuel consumption." Pick my favorite. Which will probably be a 2-liter or something that gets my van to 70mph in 5 minutes flat.

This post is already too long, but I'd like to quickly address weight. I think it's the "white pages" from Cummins, a file online that talks about improving efficiency in tractor-trailers. On the interstate, which is my ONLY application, they say losses boil down to drag, engine inefficiencies, and rolling resistance. About 65%, 15%, 20% respectively. Weight would only affect rolling resistance, a little. Just pump up a couple more psi or something, we're talking maybe 10% of 20% here, because and only because i am not accelerating on the interstate. Stop and go in the city? All bets are off, but for the non-accelerating interstate cruise roll out the waterbeds, weight doesnt matter. Otherwise these 80,000 lb semis wouldnt be getting 10 mpg.

Grill block and front air dam will probably be it for aero mods. 70mph is my challenge, Green, I can't compromise on that! Thanks allbody!