I just purchased a 91 chevy g20 conversion van with a 5.7l v8. I have removed the back seat to make room to haul cargo and I’m looking for ways to improve gas mileage. Would moving the rear mounted spare tire to the inside of the van help at all? Also what about the drag from the ladder and luggage rack? Any suggestions would be greatly appreciated!
Relocating your rear mounted spare tire is not likely to help at all. Luggage racks are known to increase drag, but it is more likely to make wind noise than make a measurable decrease in gas mileage. You could try these ideas, and if you see a difference, great, but I would expect that you will not. There’s not much you can do with this vehicle to make it get better gas mileage except do the only things proven to increase gas mileage dramatically on any vehicle: drive gently and obey the speed limit!
With the gearing of that van, drag won’t make a difference. Speed will make a small difference but not enough to make you want to do 58 MPH on a highway.
Perform a major tune up and replace the oxygen sensor. That’s probably the only way to help a vehicle like this with the aerodynamics of a brick. If you’re concerned with fuel economy you probably shouldn’t drive a twenty year old truck.
Not a lot you can do besides what’s been mentioned. Make sure you have a good set of tire, properly inflated, make sure it’s in top tune, and get rid of stuff on the roof (if you don’t need them). But there’s not much else you can do besides driving carefully…