What is "Bad" MPG for a '94 5.7L ?

Supercharged111 said:

You can pull that restrictor out of the airbox with your bare hands.

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So I get around to pulling the air box out today but I can not find any "restrictor" to pull out , I did however notice that the air tube that goes to the air cleaner snorkel from the exhaust manifold is missing.

Not fully understanding the whole purpose of the air box, at this point I am wondering : If restricted air flow is a concern / suspect for bad MPG, Why not just remove the air box and turn the air cleaner cover upside down ?

The airbox should have an insert slid into it that necks down in diameter in the middle. It has holes drilled into it and is more of a muffler than anything. Flipping the lid will only get you sucking hot, underhood air and that's no good.

Clay Smith said:

Never understood people that buy these trucks and worry about gas mileage. If that’s a concern for you than daily driving 20 year old American truck is just not a good idea. There’s thousands of cars And trucks made to get good mileage, obs chevys were never ever one of those.

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The same thing could be said about horsepower.

I have a '97 Tahoe with 4WD(3.73) and get 19+ MPG on the Highway @75+. The following are some of the improvements.
1. 18" tires off a 2017 Chevy. I inflate to +/- 44psi and that makes a big difference vs stock. Worth at least 1 MPG.
2. 100% pure synthetic fluids, probably worth over 1 MPG
3. K&N airfilter. The stock system is cold air intake.
4. Upgraded spark plugs and wires. I think I added a little more gap but can't recall.
5. Magnaflow 3" with larger 3" SST exit from muffler and exhaust pipe. For lower RPM a single exhaust can be of benefit.
6. Replaced/upgraded bearings
7. Use HiTemp Synthetic brake slide lube. This and maintaining brake adjustment properly avoid drag and that can really hurt.
8. 19+MPG is using NON Ethanol gas. Using gas with ethanol can reduce MPG by 1/4 or so. I try to use only NON ethanol gas for many reasons.
9. Maintain fuel system using Lucas often.

If I can think of more I will add. BTW, many more mods not related to MPG

bluetahoe said:

8. 19+MPG is using NON Ethanol gas. Using gas with ethanol can reduce MPG by 1/4 or so. I try to use only NON ethanol gas for many reasons.

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People always seem to say this... But my experience with my '97s has been exactly the opposite. I get much better mileage running 10% ethanol top tier gas than I do on ethanol free non top tier.

I did the math a few years back, and ethanol-free is worth anything less than a 10% premium. Right now E10 around here is about $2.10 a gallon, so any ethanol-free under $2.31 is a good deal. Unfortunately, you're not likely to find it under $2.40.

Erik the Awful said:

I did the math a few years back, and ethanol-free is worth anything less than a 10% premium. Right now E10 around here is about $2.10 a gallon, so any ethanol-free under $2.31 is a good deal. Unfortunately, you're not likely to find it under $2.40.

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On my old TBI G20 Ethanol free 91+ octane was worth a good MPG gain as long as the timing is advanced 6-8° from stock spec. The engine made alot more torque.

Supercharged111 said:

The airbox should have an insert slid into it that necks down in diameter in the middle. It has holes drilled into it and is more of a muffler than anything. Flipping the lid will only get you sucking hot, underhood air and that's no good.

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I see.

When i firts got my 98 2 door tahie i calculated something like 10mpg

name said:

Well, I guess I am glad that these are normal numbers, Is there any Mods I can do to get these numbers up ?

My gear ratio is 3:73 and the truck is used primarily as a people mover, ( no heavy towing or hauling )

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Yeah ls swap lol