91 full-size chevy help

[cRiPpLe_rOoStEr]

Originally Posted by biggygomez

ive been trying to sell my gf on one for years but she says if i put any more power in my truck it will kill me probably because shes seen my truck race

but i like the concept more power needs less work to get down the road

And the point with the supercharged combined to a raised compression ratio and a cam profiled to feature a longer intake timing is actually not exactly for power, but to increase efficiency. The longer valve timing is to simulate a power stroke longer than the compression stroke, generating a discompression which decreases the pumping losses, altough power and torque also fall, with the raised static compression ratio to keep the dynamic compression ratio closer to stock, and the supercharger to overcome the power and torque losses from the discompression. That was known as Miller cycle, and was more usual in stationary and marine engines, altough Mazda and Nissan featured it into some cars. The so-called Atkinson cycle featured in many hybrids such as the Prius is basically a Miller without the supercharger, altough it's not the real Atkinson (which featured an articulated crankshaft which really provided a power stroke effectively longer than the compression stroke).

[aardvarcus]

My 91 truck is one of those light duty K2500s, AKA a K1500 with the semi float 14 bolt 9.5” axle. Right now it is 99% stock, but I am going to try to turn it into a light duty off-roader but retain good on-road manners. I am also going to try to make it get better mileage, right now my 2001 8.1L big block out does it on the highway. My truck came with EGR, but it doesn’t work right now.

Most off-road trucks have those big steel welded bumpers, but they are way too heavy for what I am doing. I was considering repurposing an old semi-truck aluminum bumper, except shaping the front end more for aerodynamics. That was why I wondered if you were starting with an aluminum one. Plastic will probably be better for your on road application.

I have wondered in the past about making an adjustable air splitter, where you can keep it at a normal height for typical use, but be able to drop it down for when you need better handling due to more down force.

If you haven’t already, check out Aerohead’s photo album on pickup trucks. Especially look at the salt flats GMC Sonoma. It is designed for low drag and low lift.
Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - aerohead's Album: Pickup images

[Capt. Pinbacker]

Originally Posted by aardvarcus

Hello, I also have a 1991 Chevy Pickup with a rebuilt 350, 700R4, and 4x4. Is yours two or four wheel drive? You are already doing pretty good at 25 MPG, mine doesn’t get anywhere near that. Could you provide us some more details on what exactly you have done to the intake and exhaust and what you have removed as a part of the truck’s diet? If you haven’t already, routine maintenance is a good place to start, changing fluids and filters helps with efficiency and longevity.

Some low hanging fruit would be aerodynamics. Attacking the truck bed will be the easiest for the best return, to start you can do a bedcover. I don’t know what your budget it, but you can find cheap used bedcovers or even make a half bed cover out of one sheet of osb, just put it on the back half of the bed.

If yours has the recessed bucket sealed beam lights like mine, I would suggest making a heat formed lexan cover (or swapping for the non-recessed front clip). A front air dam will help as well, think of lawn edging below your front bumper to send the air around your truck, not under. You don’t need to go super low with it, just low enough to be below most of your underbody. You can also consider a partial grill block, especially during winter; just keep an eye on your temperatures (and have a way to remove it if needed).

Another big aid would be removing the engine driven fan and replacing it with a temperature controlled electric fan(s). You can get your fans from a junkyard.

This may be beyond where you want to go, but my truck had many 700R4 issues and is destined for a manual swap. I have a NV4500 waiting to go in.

What is "osb?"

[Jasen]

OSB= oriented strand board, or wood chips glued, pressed and cooked into to cheap replacement to plywood, emphasis on cheap. It's nowhere near as structurally sound and act's like a sponge when wet.
I would at least use CDX (exposure grade) plywood if not marine grade.

[Capt. Pinbacker]

Originally Posted by Jasen

OSB= oriented strand board, or wood chips glued, pressed and cooked into to cheap replacement to plywood, emphasis on cheap. It's nowhere near as structurally sound and act's like a sponge when wet.
I would at least use CDX (exposure grade) plywood if not marine grade.

I.C. i think i'll stick to masonite or coroplast.

[aardvarcus]

OSB is oriented strand board, which yes is cheap plywood replacement. There are actually good weatherproof grades of OSB, but for a bedcover the inexpensive grades will do if you protect it from the weather. For about $7 you can get a 4x8 sheet at the local big box stores, and you can get them to cut it to the width of your truck bed using their panel saw. Go to the paint department and get a gallon of mis-tinted exterior grade paint for about $5 and a cheap paint brush for $2. Go to the tools section and get two small C clamps for about $2 each to clamp it to the bed rails. Put two coats of the paint on the osb, making sure it really gets into the edges. Presto, for $20ish you have a decent bedcover.

Yes, CDX would be better, but you would still need to seal it from the weather. Do all the same steps above and you can probably get a bedcover made for about $40.

Marine plywood would be even better, but around here you can find a used bedcover for less money than one sheet of marine plywood.

I would suggest initially just getting any kind of bedcover on that you can. For a typical truck if you save one mpg you will have your $20 back in about 2000-3000 miles, at that point if you don't like it you could throw it away and have broken even. Once you see the fuel savings, it will provide better motivation to either buy a nicer bedcover or invest more in making a more durable version if your first version wears out.

[andrenoites]

I like it