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3" or 2 1/2?

Discussion in 'The Garage' started by shaun89, Dec 16, 2006.

  1. shaun89

    shaun89 1/2 ton status

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    im getting an exhaust put on my truck and im gonna put normal universal cats on it and 60 series race mufflers,with no equalizing pipe,and its dumping before the axle,now i want it to sound good but have enough back pressure to run healthy,and not loose any torgue so..anyone have any experience with this? o ya its a stock 350 out of an 88 caprice. thanks guys
     
  2. eclipse

    eclipse 1/2 ton status

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    stock 350, i'd run 2.25 pipe and that equalizing pipe, it'll still sound good and have good back pressure.
     
  3. roadnotca

    roadnotca 3/4 ton status

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    x2 on equalizer=more torque.
     
  4. muddybuddy

    muddybuddy 3/4 ton status

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    yea u really need the equalizer. id run 2.5" pipes so it would be perfect even if u end up doing mods.
     
  5. TeK

    TeK 1/2 ton status

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    I run dual 3" off the headers into an x-pipe with dual 4" coming out into 6" tips. No mufflers. enough backpressure to make the 454 happy and sounds awesome.
     
  6. mr.smartass

    mr.smartass 1 ton status Premium Member

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  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    A single 3" exhaust will give you the most amount of torque from a stock 350 engine.
     
  8. beater_k20

    beater_k20 Banned

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    2.5" with an crossover pipe (an x-pipe if you can fit it) if you plan on mods, or 2.25" if you plan on leaving it stock.
     
  9. roadnotca

    roadnotca 3/4 ton status

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    Interesting. This building upon the specs of the stock 350 as is already built for torque as opposed to high horsepower. So without the scavenging effects of the crossover, the combustion tends to be lazy, promoting torque?
     
  10. 88$PIT

    88$PIT Registered Member

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    X2...for a stock engine.
     
  11. trailblazr81

    trailblazr81 1/2 ton status

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    Are you running manifolds, shorty, or full length headers?
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    back pressure doesn't equal torque, velocity does.

    It's a fine line, go with what is known to work. Too large and you lose power because the exhaust is no longer efficient, not because there isn't enough backpressure.

    Go read some exhaust articles (especially by David Vizard) if that concept is foreign.
     
  13. 88$PIT

    88$PIT Registered Member

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    Stock manifolds with smooth bend pipe to Flowmaster Y pipe, then 3" pipe to hi-flow cat and magnaflow muffler. Way better than stock setup. I would like to go with shorty headers IF I can get bolts that don't back off every three minutes!!
     
  14. trailblazr81

    trailblazr81 1/2 ton status

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    Look in Summit or Jegs for locking header bolts. Seems on my aluminum head 383 every month or so I need to retighten mine or I start to notice an exhaust leak and find Im missing a couple. Now Ive been reading a few engine building books and they seem to agree that you want full length headers and dual 3" pipes to make the most power, and you want the H pipe in a certain place (hot spot in exhaust). I know this is not always possible with emissions, etc. but stay with the same size pipe as your collector diameter of header. I have always gone this route running 3" pipes when using full length headers, and 2.5" when stuck with manifolds or Y into single 3". Alot of people claim big pipes hurt low end, and alot say since your header collectors are 3" after that it doesnt matter. Whatever you do youll make more power than stock, and larger pipes look sick, and usually sound better IMO. And usually if you loose low end you'll make up for it in HP, unless your building a crawler.
     
  15. roadnotca

    roadnotca 3/4 ton status

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  16. 88$PIT

    88$PIT Registered Member

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    I used the stage 8 locking bolts before. It was a bust. The bolts would back off anyway with enough force to actually round off the special half moon cut washers and keep going! There has got to be something better.
     
  17. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    You can buy header bolts that are drilled for lock wire.
     
  18. roadnotca

    roadnotca 3/4 ton status

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    All those years and I never used them myself. To bad, just another hype product.:(
     
  19. beater_k20

    beater_k20 Banned

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    dont use paper header gaskets. use regular old exhaust manifold gaskets. tighten em once, and forget about em.
     
  20. gmc4cw

    gmc4cw 1/2 ton status GMOTM Winner

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    took my engine builders advice and haven't had any leaks. bolt on the headers. then run the engine till its at operating temperature. shut it off and torque down the header bolts. Never had a leak until the other weekend when my shackle bolt hit the collector flange and tweaked everything. ran it several years like that though.

    I would run 2.25" pipe with a crossover if possible. but your question was 2.5 vs. 3. so run the 2.5" if thats the only choices.
     

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