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interesting power add for SBC

Discussion in 'The Lounge' started by surpip, Jan 30, 2006.

  1. surpip

    surpip 1 ton status

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    A typical Chevy firing order is 1-8-4-3-6-5-7-2. For the vast majority of applications, this firing order works nicely and there’s probably no need to change it. But in a race application, there are various firing orders that can effectively improve power and reliability in an engine. Typically, there are seven other firing order arrangements which can be used without changing the crankshaft layout on a Chevrolet V8. These firing orders include the following:
    1-8-4-2-6-5-7-3
    1-8-7-2-6-5-4-3
    1-8-7-3-6-5-4-2
    1-5-4-3-6-8-7-2
    1-5-7-3-6-8-4-2
    1-5-7-2-6-8-4-3
    1-5-4-2-6-8-7-3 Reher-Morrison has tested the various combinations and found some interesting results. When the firing order is revised to 1-8-7-3-6-5-4-2, you’ll find some power and reliability. Now, if you race a Pro Stock car, this is no secret since the revised order has been in vogue for some time. With the revised firing order, fuel distribution dilemmas are resolved. The engine tends to run cooler, and perhaps just as important, the engine is actually smoother. How much extra power is there? Anywhere between 8 to 10 measurable horsepower. There was once a caveat here though: The average enthusiast couldn’t easily get a cam with the revised lobe positions, but not so today. Reher-Morrison sells such a package (called Big Stick Cams) for Chevy big block/Big Chief head combinations.
     
  2. theperfectgarage

    theperfectgarage 1/2 ton status

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    Pretty good story on that subject in either the new HotRod or Chevy Hi Performance, can't remember which as I subscribe to both.
     
  3. gauder

    gauder Banned

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    8-10 hp in a Pro-stock engine, for the rest of us it's not worth the added expense. Those cams are $100 more than the comparable solid roller.
     
  4. TSGB

    TSGB 1 ton status

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    :ahemgarageahem:
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I have known about these different firing orders for some time. Imagine what some shop would think if you ever took your vehicle to be worked on.

    Shop. " Uh sir, we seemed to have found your problem, your firing order was all screwed up."

    Customer. "Well did you fix it?"

    Shop. "Well, we did change the firing order back to where it should be but now your vehicle no longer runs."

    Customer. "My vehicle ran when i brought it here, i only wanted a tune-up and now you're telling me it no longer runs. Maybe you should put the firing order back like it was before when i drove the vehicle in here."

    Shop. "Sir, if we do that it won't run."

    Customer. "You already made that happen. I guess i will have to do it myself then."
    (Under his breath customer says), "This is why i don't like having people work on my vehicles. If only there were more hours in the day so i actually have time to do it right myself the first time."

    Customer. "You don't actually expect to get paid for making my vehicle no longer run do you?"

    Shop. "uh, well i did spend some time trying to make it run again." :haha:
     
  6. theperfectgarage

    theperfectgarage 1/2 ton status

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  7. Inu-Hanyou1776

    Inu-Hanyou1776 1/2 ton status

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    Moral of that shop story should be if your going to still insist on having a shop work on your stuff, you should point out to them weird modifications like that.

    Anyway, as a side note, GM builds the Gen III and up LS1, LS2, LS6, LS7, Vortec 4800, 5300, and 6000 small blocks with the firing order of 1-8-7-2-6-5-4-3.
     
  8. sled_dog

    sled_dog 1 ton status

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    Most of the big cam companies have 4-7 swap cams that change the firing order from 1-8-4-3-6-5-7-2 to 1-8-7-3-6-5-4-2. I really want to build an engine and try the setup out. They claim it allows for smoother upper RPM power and quicker throttle response(sounds like it just balances power impulses better).

    here is just one example: Comp Cams

    So its not a brand new idea.
     

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