ok, so i will be inheriting a 99 Tahoe 4wd, has about 197,876 miles on it.


Is there a way to reduce the weight of the vehicle by 2,000 pounds?


or any good ways to increase the gas mileage?

Is there a way to reduce the weight of the vehicle by 2,000 pounds?

Load that bitch up with -2000 pounds of antimatter.

Put a shitload of helium balloons under the car. That'll lighten the load a bit.

But seriously, smaller tires, shorter gears, removing any unnecessary weight, aeromodding, are all ways to improve performance and gas mileage.

Load that bitch up with -2000 pounds of antimatter.

I hear that stuff is expensive!

smaller tires, shorter gears,

*larger tires and taller gearing*

That, and "aeromodding" tends to make aerodynamics worse.

Selling it and buying a Honda.

If you refuse, then good luck.

Skinnier, taller tires. Taller gears (good luck with that).

Taking out all the stuff you don't need like carpet, dash, rear seats, speakers, spare tire and jack, etc.

Nothing you do will make the mileage very good, though.

yep and gutting the interior will make it look like shit.

keep the tires inflated to full pressure, drive conservatively and keep it up to date with maintanence.

it's all you can do really unless you want to start spending lots of money.

, smaller tires, shorter gears,

Inb4nereth sorta

Inb4nereth sorta

Your tallest gear is likely designed to put you right at peak (well, minimum) BSFC for the power output required for highway cruising.

Changing the final drive ratio will de-optimize that.

Your tallest gear is likely designed to put you right at peak (well, minimum) BSFC for the power output required for highway cruising.

Changing the final drive ratio will de-optimize that.

Where is the legal-length document on why simple mods cant be done? You're slipping, man.

Where is the legal-length document on why simple mods cant be done? You're slipping, man.

Maybe he doesn't quite have a clutch on transmission issues.

Where is the legal-length document on why simple mods cant be done? You're slipping, man.

I was working on my succinctness :)

ComradeAsh, did I make a mistake? Please inform me of it.

Oh wait, did you say that just for the pun? You crafty lad, you!

I was working on my succinctness :)


Oh yeah? Well, unsprung weight helps by cornering by putting more weight on the tires, prove me wrong.

Oh yeah? Well, unsprung weight helps by cornering by putting more weight on the tires, prove me wrong.

You are clearly wrong because pi equals exactly 3.

You are clearly wrong because pi equals exactly 3.

The magic of rounding.

The magic of rounding.

I revoke my previous statement, pi equals exactly 2.9 :mad:

I revoke my previous statement, pi equals exactly 2.9 :mad:

---------------- Now playing: VA - 031. Johann Sebastian Bach - Toccata E Fuga (BWV 565) (http://www.foxytunes.com/artist/va/track/va+-+031.+johann+sebastian+bach+-+toccata+e+fuga)

Your tallest gear is likely designed to put you right at peak (well, minimum) BSFC for the power output required for highway cruising.

Changing the final drive ratio will de-optimize that.

I don't think this is true for alot of (at least American) cars, especially vehicles designed for towing. The transmissions almost always have the same gear ratios and the final drives are changed. For instance, my boss just bought a Subby with a positrac 4.56 final drive, but you can als get them with final drives less than 4.

"Brake specific fuel consumption" is also not quite a linear equation, especially for weak engines where vacuum losses are significant.

I revoke my previous statement, pi equals exactly 2.9 :mad:

Whats that? I cant pay attention to what you're saying because I'm too busy tending to the automotive hardon I got from looking at this.
http://www.blogcdn.com/www.autoblog.com/media/2008/10/241008-2-vw.jpg

^ what's that

^ what's that


The spaceframe for the Dakar raping Touraeg 2.

Oh, and frink. Someone's been ripping off your datty.
http://i37.tinypic.com/majehs.jpg

My datto is much more rat look than that. Hell, at the moment it doesn't have a front end :D

*TERRIFIED OF UNEMPLOYMENT*

I don't think this is true for alot of (at least American) cars, especially vehicles designed for towing. The transmissions almost always have the same gear ratios and the final drives are changed. For instance, my boss just bought a Subby with a positrac 4.56 final drive, but you can als get them with final drives less than 4.

"Brake specific fuel consumption" is also not quite a linear equation, especially for weak engines where vacuum losses are significant.

Do the towing vehicles happen to have different engines? because that would explain it.

It's possible that they change the final drives for a bit of tuning of the 'feel', knowing that the bsfc numbers don't change too much in the rev range the drivers will be using, and such it is 'close enough'.

And offcourse BSFC isn't linear, I never said it was... it's not even a function of only one independent variable...

In any case, all the books I've read, and a fair whack of posts on eng-tips and other websites, have given me the idea that BSFC is usually optimized for cruising speed.

Do the towing vehicles happen to have different engines? because that would explain it.

It's possible that they change the final drives for a bit of tuning of the 'feel', knowing that the bsfc numbers don't change too much in the rev range the drivers will be using, and such it is 'close enough'.

And offcourse BSFC isn't linear, I never said it was... it's not even a function of only one independent variable...

In any case, all the books I've read, and a fair whack of posts on eng-tips and other websites, have given me the idea that BSFC is usually optimized for cruising speed.

It's just got a 350 with EFI. It didn't even need leaded gasoline.

And I meant that the fuel consumption of an engine depends on those figures for BSFC, but you can change things around to where you have the throttle wide open at some cruising speed and use less fuel because of less restriction.

It's just got a 350 with EFI. It didn't even need leaded gasoline.

And I meant that the fuel consumption of an engine depends on those figures for BSFC, but you can change things around to where you have the throttle wide open at some cruising speed and use less fuel because of less restriction.

BSFC takes stuff like that into account.

BSFC takes stuff like that into account.

The end result, yes, but it is meaningless to postulate the BSFC without actual numbers. To wit, changing the final drive changes the engine load and how much throttle needs to be applied at a given cruising speed. The BSFC calculation gets a single variable changed, but power must be experimentally verified. If you make the gears taller, it may or may not make the engine more efficient depending on its cruising RPM, how rich the fuel mixture is, etc.

*larger tires and taller gearing*

That, and "aeromodding" tends to make aerodynamics worse.

Thanks for the fix on tires and gearing. My bad :D

Anyways, it really only makes it worse if you do a shitty job of it. If you take the proper time and effort it can do quite well.

The end result, yes, but it is meaningless to postulate the BSFC without actual numbers. To wit, changing the final drive changes the engine load and how much throttle needs to be applied at a given cruising speed. The BSFC calculation gets a single variable changed, but power must be experimentally verified. If you make the gears taller, it may or may not make the engine more efficient depending on its cruising RPM, how rich the fuel mixture is, etc.

BSFC is experimentally measured fuel consumption at every power and torque combination, i.e. it links 3 variables, not 2.

There isn't really anything else to take into account. There's things like air temperature, but that ain't changing with your gears. There's the efficency of the gears themselves - but lets just call that too irrelevant to bother with, shall we?

what kind of engine is in this 99 tahoe, i own a 2003 gmc seirra half-ton pickup for my HVAC work and average about 22 mpg on the highway with a 4.8 litre V8 and 3.73/1 rear axle ratio.
In my opinion there isn't really much you can do modification wise to lower fuel consumption, but keep tires properly inflated give the engine a good tune up. Spark plugs, wires etc. and drive consertively. if your vehicle is set up like mine is you shoud be able to get the same mileage out of yours except yours is 4wd and my pickup is the 2wd work truck

^^ thats what i said a page ago