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Looking for Better MPG Tips, Tricks, and Suggestions........

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ford_assassin, Nov 13, 2003.

  1. ford_assassin

    ford_assassin 1/2 ton status

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    Okay guys, I am just trying to squeeze alittle more gas mileage out of my '86 stock Blazer (350) for the 30 min trip to and from work everyday. I have alittle extra cash coming and the "better half" says I can either buy a set of shorty "smog" headers OR a Crane HI-6 ignition system w/external Fireball coil......but not both. Sooner or later I'll get both, but not today.

    So, which would you do? I already have a 3" CarSound CAT and 3" single exhaust w/Dynomax Race Magnum UltraFlo muffler (straight-through design). The ignition is bone stock coil-in-cap HEI w/8.8mm plug wires. I have run Crane HI-6 ignitions in the past and loved them 10x over the MSD 6A-L.... especially the rev-limiters.

    The rest of the Blazer is nothing special. 33" tires on 15x10 M/T Classics, 4.11 posi gears, 700-R4 tranny, and the gutless stock 160HP 350.

    I had considered switching from my clutch driven stock fan to a electric fan setup, however I worry that an electric wouldn't be enough to coil the SBC 400 that I have in the works, especially with the A/C blasting in the summers.

    The new 400 will have a set Pro Topline (iron) heads to max HP and TQ output. When completed it should double the HP/TQ of what I have now without upsetting the "smog nazis" here in Cali. A high volume water pump will be added at that time too.

    I also wondered if an open element air cleaner with a 6-8" filter would yield any mileage gains.

    Please keep in mind that I live in Cali and I get bi-yearly SMOG checks as well as the time to time checks for mods by the local cops. So please keep you suggestions under what can and can't be done with Cali emissions equipment/standards.
     
  2. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    I would think the ignition upgrade would be a good start. My opinion is that improving flow of air in and out of the engine makes it easier to burn more gas, but thats not a fact or anything.
     
  3. fwdjunky

    fwdjunky 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    My dad always told me headers don't help gas milage at all because you very quickly become addicted to the sound they make when you put your foot on the floor. That seems funny, but I think there is a certain amount of truth to it. Just something to consider.
     
  4. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    Headers configured correctly will help mileage, the Crane will not help. Full length headers and a complete free flowing exhaust would net some mileage saving if you can keep your foot out of it. I am torn on the shorties, I tend to think they won't make a noticeable difference.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    Open element air cleaner will likely hurt power production. (engine compartment air is sometimes in the 180* range while sitting)

    Ignition is pointless *if* the stock system is in top shape. Plugs, wires, cap, rotor, vacuum and mechanical advance all in good working shape.

    Shorty headers, by all accounts, don't do much, if anything, for low end power, and the worst mileage on these trucks is around town. Long tube headers are a better bet on most trucks, and they can be had with all emissions stuff.
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    I agree with all others. HEI is a great stock ignition. If better MPG is your only reason for wanting a CD ignition box, you're wasting your money.

    I'd say go with the long tubes.
     
  7. Derf00

    Derf00 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    Drive a little more conservatively, put a little more air in your tires and save your money, that will do more for you than the headers and ignition.
     
  8. ford_assassin

    ford_assassin 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    [ QUOTE ]
    Long tube headers are a better bet on most trucks, and they can be had with all emissions stuff.

    [/ QUOTE ]

    I have yet to see a long tube header for my '86 BLAZER, not truck. Yes, the smog guys here will check the carb number because Blazers are considered "autos" while open bed trucks are "commercial". So unless the carb exemption number says its for a Blazer....its useless to me.

    So, I am dying to know where to buy the full length Cali smog exempt headers you spoke of.

    I think Thorley might make them, but they are going to cost $600+ and that kinda kills the money limit thing with the wife.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    Hedman lists a pair over at their website, says 50 state legal for 83-92, and although the year range is wrong, that should be the right application.

    Didn't realize CA lumped Blazers into the auto category, here we make that choice ourselves.
     
  10. k5guyva

    k5guyva 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    To really save fuel, try reducing weight. Maybe a soft top? I think of the choices you stated, the headers would be my pick. I wouldn't expect miracles.

    To really get some effect at the pump, you have to reduce the rolling resistance of the truck. You can make it more aerodynamic or you can lose weight. You can make the engine more effective at producing the power by eliminating some inefficiencies, but that isn't where the big gains are.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    The problem is, you can't cut the weight down, nor can you reduce the drag coefficient on these vehicles easily.

    Heck, if you think about it, even the new trucks, which are quite a bit more aerodynamic (at least by looks) get gas mileage only a bit better than ours.

    And in actuality, there are huge gains to be made by making the drivetrain more efficient, which is why the cases are chain driven, the lubricants are thinner or synthetic, the combustion chamber design has changed immensely, compression is up with the same grade of gas, the camshafts are roller, etc.

    I'm not saying it can be done cheaply, but if you can make the same size engine produce power more efficiently, that power can be expressed in increased MPG. If you can make 30 more ftlbs of torque and 15HP more at 1500RPM while cruising, your foot will be in the pedal less, and you will use less gas.

    Not saying that weight reduction and aerodynamics don't play huge factors, but they are almost impossible to practically change to an extent that actually matters.
     
  12. Derf00

    Derf00 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    Edlebrock list their TES headers for your '86.

    Eldebrock Exhaust Systems

    Part # #6863.
     
  13. tecton

    tecton 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    wings wont even help?!?!


    but, but, but [​IMG]
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    [ QUOTE ]
    wings wont even help?!?!

    [/ QUOTE ]

    Everyone knows wings are about performance, not economy. Sheesh! /forums/images/graemlins/rotfl.gif
     
  15. kennyw

    kennyw N9PHW Premium Member

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    [ QUOTE ]
    Not saying that weight reduction and aerodynamics don't play huge factors, but they are almost impossible to practically change to an extent that actually matters.

    [/ QUOTE ]

    S10 body on 1/2 ton running gear would probably help /forums/images/graemlins/thumb.gif
     
  16. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    Just a quick question............

    You're worried about smog stuff, but yet want a 400? Gonna trailer it everywhere and Green Sticker it?
     
  17. K1Orion

    K1Orion 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    [ QUOTE ]
    wings wont even help?!?!


    but, but, but

    [/ QUOTE ]

    I believe I can fly, I believe I can touch the sky!!! /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif
     
  18. ford_assassin

    ford_assassin 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    [ QUOTE ]
    Hedman lists a pair over at their website, says 50 state legal for 83-92, and although the year range is wrong, that should be the right application.

    [/ QUOTE ]

    What do you mean the year range is wrong? My Blazer is a '86. Did I miss something? Do you have the part number?

    [ QUOTE ]
    ...if you can make the same size engine produce power more efficiently, that power can be expressed in increased MPG. If you can make 30 more ftlbs of torque and 15HP more at 1500RPM while cruising, your foot will be in the pedal less, and you will use less gas.


    [/ QUOTE ]

    Believe it or not, but that was my intent with the mods to the Blazer. I know if I free up enough HP and the same cruising RPM my MPG would increase.

    When I swapped out my 305 for a mild 383 in my '87 Camaro (same intake/carb as the Blazer) I gained 5 mpg with no other changes. I already had electric fan, shorty headers, and an open element air cleaner before the 383 swap.


    [ QUOTE ]
    Edlebrock list their TES headers for your '86.

    Eldebrock Exhaust Systems

    [/ QUOTE ]

    Edelbrock doesn't make a long tube header, they are all "shorty's".


    [ QUOTE ]
    Just a quick question............

    You're worried about smog stuff, but yet want a 400? Gonna trailer it everywhere and Green Sticker it?

    [/ QUOTE ]

    A SBC 400 wouldn't smog any different than a 350 (assuming everything is the same), and on the outside ALL '55-'98 Chevy SB V8's look the same. So the smog sniffer guys wouldn't be the wiser.
     
  19. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    [ QUOTE ]
    What do you mean the year range is wrong? My Blazer is a '86. Did I miss something? Do you have the part number?

    [/ QUOTE ]


    They list them as being for 82-92 K5 Blazers. No such animal, so dunno what they meant. Thats the S10 breakdown IIRC, but they MEAN K5. Soo...they should be right. No I don't have the part number, but go to google, type in hedman headers, and check out their website. It has all the part numbers right there. Alternatively, you can probably go to summit or jegs online and do the same thing.


    [ QUOTE ]
    Believe it or not, but that was my intent with the mods to the Blazer. I know if I free up enough HP and the same cruising RPM my MPG would increase.


    [/ QUOTE ]

    You'll never be able to gain enough "free" power from modifications in MPG to recoup the money spent on the modifications. However, the plus side is, once you are done, you THINK you are saving money at the pump, but the real kicker is, a vehicle with more power is fun to drive, and if it does cost you less to have more fun driving it, THAT's worth money. (in your case, you gained 5MPG with a 383, but how much did that 383 cost you, and how many miles would you have to drive before those extra 5MPG "paid off" the motor? /forums/images/graemlins/smile.gif) Not making fun of you for it, as my TPI engine SHOULD get great mileage, but I don't dare add up all the receipts on how much it is going to cost to finish. I've already figured out it will take 10 or 15 years to recoup that money in gas saved.
     
  20. ford_assassin

    ford_assassin 1/2 ton status

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    Re: Looking for Alittle Gas Mileage.....Headers or Better Ignition System?

    [ QUOTE ]
    You'll never be able to gain enough "free" power from modifications in MPG to recoup the money spent on the modifications. However, the plus side is, once you are done, you THINK you are saving money at the pump, but the real kicker is, a vehicle with more power is fun to drive, and if it does cost you less to have more fun driving it, THAT's worth money. (in your case, you gained 5MPG with a 383, but how much did that 383 cost you, and how many miles would you have to drive before those extra 5MPG "paid off" the motor? /forums/images/graemlins/smile.gif) Not making fun of you for it, as my TPI engine SHOULD get great mileage, but I don't dare add up all the receipts on how much it is going to cost to finish. I've already figured out it will take 10 or 15 years to recoup that money in gas saved.

    [/ QUOTE ]


    I see what you are getting at, but believe me when I say that I drive this thing so often that the money spent with pay for itself pretty quickly. Especially since I don't plan on selling the truck, at least not for 10 years.....at least.

    Lets look at this from another angle.....less money.

    Would advancing the timing help at all? I worry about playing with the timing being that this is a computer-controlled setup. Also, what about some metering rod/hanger changes? I played with a couple sets with the Camaro's 383 and it helped with a bog issue after the motor was first swapped it. I didn't even think about it with a stock 350. I guess it wouldn't hurt.
     

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