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Thread: Equal length turbo headers?

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    Newbie pipes1243's Avatar
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    Equal length turbo headers?

    I know some companies have turbo kits out there for our f-bodies, but does anyone make equal length turbo headers? I drew up some in Pro-E, and all the primaries are between 22-24in, and I was kind of wondering if the 2in difference in length would defeat the purpose.

    Cyl #1 is 22in
    Cyl #3 is 24.1
    Cyl #5 is 24.4

    I know making them equal length isn't necessary, but I was kind of doing it just for fun. They're going to be out of 304 stainless, and probably 12ga. Another question, is 12ga(.105) overkill for tube thickness? I'd rather have them last me forever, and hold up past anything I'd do.

    Thanks
    98 Camaro: 5spd, LSD 3.42 gears, Diamond Forged Pistons 8.5:1, Abbott Racing Turbo Cam .571/.556, SPEC Stage 3+ clutch, APR head studs, Lightly Ported L26 heads, EGR Delete, A/C Delete.

    Turbo build in progress.

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  3. #2
    Mod Squad HAZ-Matt's Avatar
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    Well there are those that think that trying to tune the length, and subsequently equal length, isn't really all that important when you are feeding the turbine. But you can get a little exhaust tuning going. In general if they are slightly unequal length you will get a slightly broader area of tuning, but the effect won't be large as if they are equal.
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    Newbie pipes1243's Avatar
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    Quote Originally Posted by HAZ-Matt View Post
    Well there are those that think that trying to tune the length, and subsequently equal length, isn't really all that important when you are feeding the turbine. But you can get a little exhaust tuning going. In general if they are slightly unequal length you will get a slightly broader area of tuning, but the effect won't be large as if they are equal.
    When you say exhaust tuning, do you mean using the EGT's? I know that if one primary is longer then the other, the longer one be hotter then the shorter one. I wanted to put EGT sensors on each primary to tune the individual injectors the best I can. As far as the exhaust feeding the turbine, I was under the impression that if the lengths are equal, it will keep a more consistent flow over the turbine with each cylinder's exhaust pulse. What do you think about the tube thickness, is 11 or 12ga too much?
    98 Camaro: 5spd, LSD 3.42 gears, Diamond Forged Pistons 8.5:1, Abbott Racing Turbo Cam .571/.556, SPEC Stage 3+ clutch, APR head studs, Lightly Ported L26 heads, EGR Delete, A/C Delete.

    Turbo build in progress.

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    I use 10ga without issues.

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    Mod Squad HAZ-Matt's Avatar
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    What I was actually talking about was resonance tuning, which is a questionable benefit when you don't really want valve overlap and the exhaust pressure is relatively high.

    I suppose if they are equal lengths then the pulses will arrive at the turbine consistently, at least while at about the same RPM. But I don't think the small difference in length is going to hurt you that much. Many turbo aps have manifolds that are more or less like logs.
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    Beer Connoisseur Tpunk's Avatar
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    The vast majority of turbo setups basically use logs like Matt said. Generally speaking it's more about keeping heat in than it is about exhaust pulse. You won't really achieve any scavenging effect with that much back pressure. I'd just get whatever you come up with ceramic coated. Odds are that will help more than any sophisticated design involving tuned length.
    John, 1999 Isuzu Vehicross Ironman Edition
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    Newbie pipes1243's Avatar
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    Quote Originally Posted by Tpunk View Post
    The vast majority of turbo setups basically use logs like Matt said. Generally speaking it's more about keeping heat in than it is about exhaust pulse. You won't really achieve any scavenging effect with that much back pressure. I'd just get whatever you come up with ceramic coated. Odds are that will help more than any sophisticated design involving tuned length.
    Getting them coated sounds like a good idea. I know that log style would be easier and still work just fine, but I'd be doing equal length just for an added challenge. Since I'll be doing equal length I'd like to have the best possible results, and don't want to cut corners causing any possible benefits to be lost. I think I'll just redesign them to be within a half inch of each other.

    Thanks everyone for the help. This spring/summer when I make them I'll post some pics, and possibly make an extra set to sell if they turn out good.
    98 Camaro: 5spd, LSD 3.42 gears, Diamond Forged Pistons 8.5:1, Abbott Racing Turbo Cam .571/.556, SPEC Stage 3+ clutch, APR head studs, Lightly Ported L26 heads, EGR Delete, A/C Delete.

    Turbo build in progress.

  9. #8
    Full Throttle Extreme! trb0355's Avatar
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    There is also supposed to be benefits in arranging the pipes into the collector according to firing order. On my V8 they fire in a rotational pattern which may or may not help scavenging the other primaries. I dunno, sounded good so i built them that way.

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  10. #9
    Gonna eat me some peaches Driver_10's Avatar
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    Quote Originally Posted by Tpunk View Post
    The vast majority of turbo setups basically use logs like Matt said. Generally speaking it's more about keeping heat in than it is about exhaust pulse. You won't really achieve any scavenging effect with that much back pressure. I'd just get whatever you come up with ceramic coated. Odds are that will help more than any sophisticated design involving tuned length.
    Equal length turbo headers seem to produce a slightly broader torque range and better acoustics. There is some benefit to keeping the load even on all cylinders via EL headers. A 660 or even-fire 3800 will benifit especially well assuming that a divided turbine housing is used.
    Last edited by Driver_10; 12-03-2011 at 09:22 AM.
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  11. #10
    Mod Squad HAZ-Matt's Avatar
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    Empirical evidence or purely theoretical?

    If you are sweeping through the revs you are changing the time between pulses anyway.
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  12. #11
    Full Throttle Extreme! trb0355's Avatar
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    The only reason the torque curve could be broader is simply spooling the turbo faster thru a divided housing and a header setup that maximizes the pulses to "drive" the turbo harder, better heat retention etc. The exhaust is usually under double the pressure in the intake so how much does header design ultimately affect power? Most of the street oriented kits people build wont benefit much from overthinking. The head flow, turbo sizing and intercooling simply arent built to race specs to matter much.

    Stromberger Performance
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  13. #12
    Full Throttle Extreme! trb0355's Avatar
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    Heres a great example of using the pulses to your advantage. A little upgrade project im currently doing to my Trans Am.
    4 into 2 design made by WrenchRat turbo systems for a V8 but the same principle would apply to a heavy hitter V6.
    Attached Images Attached Images
    Last edited by trb0355; 12-05-2011 at 07:14 PM.

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    98 camaro V6 turbo
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  14. #13
    Gonna eat me some peaches Driver_10's Avatar
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    Quote Originally Posted by HAZ-Matt View Post
    Empirical evidence or purely theoretical?

    If you are sweeping through the revs you are changing the time between pulses anyway.
    If you really think about it, sweeping through the revs would only change the frequency of the pulsing cycle, NOT the actual phasing of the pulses. The pulses will arrive at the same time in relation to 720 degrees of engine rotation.

    At least that makes sense in my head, assuming Im not missing something
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  15. #14
    Gonna eat me some peaches Driver_10's Avatar
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    Quote Originally Posted by trb0355 View Post
    Heres a great example of using the pulses to your advantage. A little upgrade project im currently doing to my Trans Am.
    4 into 2 design made by WrenchRat turbo systems for a V8 but the same principle would apply to a heavy hitter V6.
    The effect would be amplified on an even fire v6, 180 "flat-plane" v8, "flat-plane" 4 cyl, 60 degree v12 or 90 degree v10.
    Gonna be quiet again for a little while, so show some patience. It will be worth the wait.
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  16. #15
    Full Throttle Extreme! trb0355's Avatar
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    Quote Originally Posted by Driver_10 View Post
    If you really think about it, sweeping through the revs would only change the frequency of the pulsing cycle, NOT the actual phasing of the pulses. The pulses will arrive at the same time in relation to 720 degrees of engine rotation.

    At least that makes sense in my head, assuming Im not missing something
    I agree. It would still be beneficial thru the entire rev range. A good place to see pulse phasing and an extra bit of thinking is the 4 cyl. Evo crowd and similar setups. Those guys are driving BIG turbos with small cubes and need to maximize everything they can with header design.

    Stromberger Performance
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    98 camaro V6 turbo
    428 whp for 600 bucks and it keeps on running.

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