454 Big Block Gas Mileage Improvement

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Thread: 454 Big Block Gas Mileage Improvement

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    Walking
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    454 Big Block Gas Mileage Improvement

    I'm looking for suggestions (creative and otherwise) on how to improve gas mileage on a '97 GMC K2500 with a 454 big block engine (gears are 4.10, I think??). I know about all the basics - keep tire pressure up, new plugs/wires, etc., keep your foot off the gas as much as possible, etc., etc. I'm also aware that these engines weren't made for mileage. They're made for working and towing. All that aside, what about adding headers? Will this help the mileage or hurt it? What about a performance exhaust? Would a K&N air filter help? Has anyhone had success doing any of these things? What have you had success with? Thanks very much for your input. I look forward to reading your replies.

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    6.2 Liter LS9 Supercharged V8 MrCritical's Avatar
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    Re: 454 Big Block Gas Mileage Improvement

    First of all, I love this engine. I stupidly sold my '71 ElCamino 454 SS years ago.

    The air filter and the headers will increase mileage somewhat, as long as you don't drive more agressively to feel and hear the newfound power.

    The best fuel mileage increase I found was slower takeoffs and cruising at 60-65 mph instead of 70 and above. I believe my benefit was somewhere around 1.2 to 2.1 mpg.

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    Re: 454 Big Block Gas Mileage Improvement

    What kind of mileage do you get out of your '97? I get about 12 out of a 2000 K2500 crewcab. 7.4L with 4.10 rear end.
    Last edited by steelmanwy; 02-16-2010 at 01:41 PM.

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    Re: 454 Big Block Gas Mileage Improvement

    here is my list:

    - Like you said, start with the basics, new fuel filter, new plugs and wires, new cap and rotor. Also, throw in some synthetic oil, this helps a little bit, also better for your engine while towing.

    - Definitely add a high flow intake, also a throttle body spacer. Put a high flow muffler on it as well. These 454's respond a lot to these add on's. Remember an engine is just like a big air pump. The faster you can get air in and out, the more effecient it becomes. Headers help a little bit, but in my opinion, on the newer trucks just stick with the manifolds.

    - Add a performance tune ( superchips, hypertech, or even a custom tune ). Not only will this add power, these can really help with mileage.

    - If you are really serious, you can get a gear vendors overdrive as well. If you have 4:10's, this would really help while cruising down the highway. They aren't cheap, about $2500, but they make a big difference.

    I have done pretty much all the above ( except for the overdrive ) and went from 13 city, 18 hwy to about 14-15 city and 21 hwy. Not a huge gain, but it has a lot more power too. From what I have seen, big blocks respond even more.
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    Re: 454 Big Block Gas Mileage Improvement

    How many thousands are you willing to spend to save a couple of pennies on gas? You will get the most bang for your dollar by driving right. Pretend there is a raw egg rolling around in the bed of your truck and drive in such a way that you keep the egg from breaking.
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    Re: 454 Big Block Gas Mileage Improvement

    Quote Originally Posted by dr.gizmo View Post
    How many thousands are you willing to spend to save a couple of pennies on gas? You will get the most bang for your dollar by driving right. Pretend there is a raw egg rolling around in the bed of your truck and drive in such a way that you keep the egg from breaking.
    I always said pretend there is an egg under the gas pedal.

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    Re: 454 Big Block Gas Mileage Improvement

    Quote Originally Posted by dr.gizmo View Post
    How many thousands are you willing to spend to save a couple of pennies on gas? You will get the most bang for your dollar by driving right. Pretend there is a raw egg rolling around in the bed of your truck and drive in such a way that you keep the egg from breaking.
    While I agree with you 100% on it is mostly in your driving style, there are some cheap gains to be had.

    Like I mentioned earlier, I gained 4 mpg on the highway with just a few basic mods.

    Tune-up ( fuel filter, plugs, wires, cap & rotor ) & synthetic oil change = $150
    High flow intake and intake spacer = $300
    High flow muffler = $200
    Performance tune = $300

    So for a total of roughly $950, I gained 20% in my highway mileage. Not to mention, I probably gained 20 hp and 30+ ft. lbs. of torque.
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    Re: 454 Big Block Gas Mileage Improvement

    Wouldn't a better tranny help too...something like a 700r4? ya kno with overdrive?
    and what ratio would be a well over all good ratio for the rear axle?

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    Re: 454 Big Block Gas Mileage Improvement

    Quote Originally Posted by Babbit View Post
    Wouldn't a better tranny help too...something like a 700r4? ya kno with overdrive?
    and what ratio would be a well over all good ratio for the rear axle?
    A '97 ought to have a 4L80 which would include overdrive.

    For mileage on a big block I'd pick the lowest possible axle ratio. There's enough torque available
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