[ComputernerdBD]

Hi everyone. This is my first post on this forum. I drive a 1998 GMC Jimmy 4x4 with a 4.3L V6 engine and a 4L60E automatic transmission (I live in the Hudson Valley and go to college in upstate NY where they don't cancel class JUST because there is 2 feet of snow and ice on the ground. Plus I go camping alot and I use my 4x4 alot.) and it is lightly modified to try to get better gas mileage and reliability. I have a cold air intake (MPG ^) and a transmission cooler (Reliability ^) and I used to have a throttle body spacer on the engine (MPG ^?) that I will be reinstalling next weekend now that I found a way to fit both the CAI and the spacer on this engine. I also have a Posi-Lok system, so I can not only be sure that my 4x4 locks in properly, but that it unlocks properly, so there is minimal drag. I usually use Royal Purple 5W-30 oil (weight the 4.3L calls for), minimize A/C use and use cruise control as much as possible to further save gas. I just did a tune up with a new distributor cap/rotor and AC Delco RapidFire spark plugs. Other than that, it is totally stock. I just replaced some rotting vacuum lines and I determined that at 65mph, I get between 19-21mpg (verified by factory trip computer), depending whether or not I have the aerodynamic cargo box (almost no mileage penalty) or the bike rack (some penalty because the bike wheel is in the wind). In town, depending on idle time (both waiting for traffic lights and to let the engine warm up), I get between 10 and 15mpg. For a V6 that has roots with a V8 engine design (a 4.3L is a 5.7L with 2 cylinders deleted) with 108k miles, that isn't too bad, but I am trying to increase my MPGs without sacrificing it's usefullness in the snow and offroad.


I saw on Top Gear US Death Valley challenge how one of the challengers who drove a Chevy Blazer fullsize through all the offroad challenges WON the final challenge that tested fuel economy by putting a cardboard boat tail on it and was the only one who finished without either blowing a tire or running out of gas. Just how could I build one for this truck that will not only be sturdy, but legal? I was thinking of maybe using the trailer hitch and the roof rack rear bolts as attachment points since they seem the most secure. Maybe install LED trailer lights and the license plate to the tail cone of the boat tail and plug it into the existing harness so I can remove it if I want to tow or use the bike rack. Since I like planes, maybe even put a tail fin on top of it to make the truck look like a plane? LOL JK

I have other aerodynamic mods planned like a light coating of bedliner paint (either with or without rubber texture) since this paint has alot of scratches down to metal (but no rust. Plus I keep this truck clean, so there is minimal dirt drag) and fixing damage to the front bumper (big crack/bent. Not good for aerodynamics) to try to reduce the drag coefficient. I have P235/75R15 tires (just larger than factory spec), so there are less revolutions per mile. I have been decreasing the weight of the contents of the interior, but some stuff I can't remove. I have a box of emergency equipment and spare fluids for everything among other things since this truck does enter places where there is no cell service and I might have to perform repairs myself if something happens.

Thanks