I have a 97 silverado z71 and i was wanting to know what the vortec box that sits behind the TB??

Another quick ? on gas mileage this truck has 155k on it and i get about 11-12 mpg in town is that normal ??
Mods so far
-Intake
-exhaust

ok ok i tired writing this fast and you guy arnt understanding. Ok i put an intake on my truck and on top of the TB theres a hat that goes over the TB and then goes to the air box but off that hat theres a black box that sits right behind it and it says vortec on it what is that box for does it serve for something??.

And about the gas mileage i wanted to know if it was normal not how to get 20mpg you jack A**

Can't answer about the vortex box, sry.
But your 'around town' milage sounds about normal to me.

And welcome to GM-Trucks.com btw.

Clean your MAF sensor, replace your PCV valve, change your spark plugs, and do some Seafoam treatments in the gas tank and brake booster vacuum line. Then look into a PCM tune.

Your gas mileage is average. I get about 13.8 out on the road, a little less in town. I picked up 1 mpg when I switched over to Mobil One Synthetic Oil. As far as the box, I figure they needed a place to write Vortec so they built a box. My 95 Blazer has a plastic lid on the top of the engine that seems to serve no purpose other than a place to Vortec.

Okay, the box is a air storage area. The epa requires a specified amount or air space in the intake system. In order to do this, they caculate the size of the tubes, bends and then add a box to make up for the difference. If you follow the air system to the fender, there is another box up there as well.

As for the mileage, before the new motor, I was getting 22-24 mpg. I would do a tune up, plugs, wires, pcv, cap, rotor button, etc. I would also add some seafoam to the tank for a few tanks to clean out the intake system. If you have the two piece composite intake system witht eh spider injectors, I would replace them with the update and clean the intake manifold.

Thanks for the info guys and for changing the spider ill fix that when it brakes theres no need to throw 350$ at it and gain maybe 1-2mpg not worth it to me. Ok so i have an intake can i take that box out ?? and will it help???

The box is to make the air rushing through the intake to the throttle body quieter.
My 98 gets 14 city, and nearly 20 highway.

My truck averages on 14mpg for in town. i got a hypertech tune, aftermarket intake and exhuast and headers. Didnt notice to much for in town. On highway i can get 500km (310miles) to a half tank and thats just keeping a steady speed of 110km/h (68 m/h).

The little Vortec box is similar to the boost bottles used on snowmobiles and motorcycles and so on. It is supposed to change the pressure balance to improve low to midrange driveablilty, throttle response, fuel economy and horsepower. I have no idea if it actually does that on these fourstroke motors, but on two strokes it is noticeable and sometimes requires a re-jet.
My truck doesnt burn the fuel, it inhales it....... I am running 38.5 thornbirds. Although your mileage sounds low, it is probably correct.

The Vortec box slows down the airflow!!! I took mine off and capped the hole with a rubber plumbing cap...cost like 89 cents!! I average 17 in the winter and 18.5 in the summer...trips i get 20mpg going 80mph. But, I have 2wd, you have 4wd so yours sounds normal to me. But get rid of that useless box!

I took my air lid cover off so its identical to a cold air intake and averaged .8 mpg better. My 98 with everything original and 40k miles, I get 18.5 highway and 16 city.. right now with a crazy cold winter (plus it only comes out on nice days) i ave 13.9mpg. thats warming it up before driving too. All i have is a flowmaster exhaust, the air lid cover removed and mobil 1 oil. so with your miles it might be about right. I had a 99 yukon with the 5.7 and i averaged 12 with it, but that was a heavy truck. I'd do a basic tune-up and see what you get. I have noticed they are very touchy on how you drive them, a little lead foot and they get thursty

Ya everyone is telling me its these very cold days that are killing my mpg and i havent had the truck but 2 months and its all been winter so ill wait and see. and for the box i was thinking the same thing (plumbing cap lol i used them alot) but will it change the mileage or hurt power with removing it ?? thanks guys

i wouldn't take it off at all, just leave it. a 2wd truck will always be better then a 4wd for fuel consumption. Iuse to own a 2wd gmc and that thing would get amazing fuel mileage. it got 26mpg then i wrote it off. Now i got the 4wd gmc. When i bought the truck it had a just a sweet talker bottle exhaust on duals thats it for mods. And that thing got really crap mileage.

Why not take it off ?? even if its for looks its not going to hurt anything

what would be the point?

Now....Be nice

the point to me is to make the engine bay look cleaner thats all and gmtech what was that all about ?

you pissed me off

im sorry i didnt mean to offend or anything just giving adive, do you wanna hug?

close this thred i got my answer thanks everyone