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what size exhaust is best??

Discussion in 'Engine Building' started by eg6sir, Dec 6, 2005.

  1. eg6sir

    eg6sir Supa Mod Moderator VIP

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    ok.. i'm gonna be going to get an exhaust made.. and i was wondering what size would be better.. 2.25 or 2.5.. i have a b16 sir2 w/ ctr cams, DC 4-2-1 header.. i have an exhaust on there but the piping is crap.. it was a rookie job.. so i am replacing it with mandrel bent piping..so what size would be best..??
     
  2. formby

    formby learning in progress

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    i would get 2.25 mandrel for NA....2.5 if 1.8L+......
     
  3. Autozoner n civic owner

    Autozoner n civic owner Junior Member

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    there are a lot of myths about exhaust system sizes that I hope to dispell. If the diameter is too big and there is not enough back pressure in the exhaust system, you will cause damage to the piston rings. the following is a list of suggested diameters for the given motor sizes:

    1.6 liter motor: 2.00 inches
    1.7 - 1.8: 2.25 inches
    2.0 - 2.2: 2.50 inches
    2.3 - 2.4: 2.75 inches

    for turbo, supercharged, or nitrous applications, add an extra 0.50 inch to the diameter.
    This info is straight out of the High Performance Honda Builders Handbook in which they have done the proper math calculations for each size motor. Call this bullshit if you will, but the math backs it up.
     
  4. integraslut78

    integraslut78 Stylus DJ Extraordinaire

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    I have an Invidia 2.25 full catback and it worls real well for my LS/VTEC.
    If you are going turbo go with the 2.5-3", otherwise you should be okay with the 2.25"
     
  5. pissedoffsol

    pissedoffsol RETIRED

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    damage to the piston rings from an exhaust.

    THAT'S a new one.... ROFL

    if its in a book, i'd start a fire with the paper from it, cuz that's about all its worth.


    personally, i'd go 60mm on a high revving b16 with ctr cams... 2.36 inches to be exhaust.

    if you plan to go for more power later, go for a full 2.5"
     
  6. eg6sir

    eg6sir Supa Mod Moderator VIP

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    thanks everyone.. i was thinking 2.5 might be too big and 2.25 a little small.. so i guess i'll take pissedoffsol's advice and get 60mm/2.36 piping..
     
  7. driverunknown

    driverunknown Senior Member

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    Well, you don't want the muffler bearings to wear out.
     
  8. Autozoner n civic owner

    Autozoner n civic owner Junior Member

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    i know it sounds funny, but without backpressure, the piston rings will become unseated and not seal right. I have seen this problem many times as now the latest trend in my town is to hollow the cat, scrap the muffler and straight pipe the shit. sounds like shit and they are burning more oil now.
     
  9. Cashizslick

    Cashizslick !i!i!i!i!i!i!i!i!i!i!i!

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    Like B said its all in the plans you have for your car. If you plan on swapping a motor in but leaving it reletivaly stock, then you should stick with 2.25 piping instead of the 2.36 IMHO.

    BTW if u want i am selling a thermal R&D rear section for a 92 civic . . . . $50/obo y0
     
  10. eg6sir

    eg6sir Supa Mod Moderator VIP

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    ya know thanks for the advice, but i dont think i'll take it .. especially from an Autozoner..
     
  11. phyregod

    phyregod !!YTINASNI

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    Thats probably because your friends are fucking stupid and are going for the "free" mods. So they probably opted for the cheapest piece of shit air filter they could find, and sucked in dirt and other debris, and scratched their cylinder walls/rings all to hell causing the ring failure. Thats my theory anyway.

    Back pressure is BAD. You want high-speed flow so the exhaust from one cylinder will scavenge the exhaust of the other, causing a kind of "suction" while that cylinder's exhaust valves are open. True, bigger piping will slow down flow and harm the scavenging effect but that has nothing to do with "back pressure"

    Personally, I'd go with 2"-2.25". If you are planning nos, up it to 2.5"
     
  12. jimboburgess

    jimboburgess Go fast, Go Cheap

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    The engines displacement is so small that i don't think it warrents anythign more than 2.5 inch.
    The LS stock exhaust manifold is, 1.75 inches. I am running a 2.5 inch down pipe with my turbo app.
     
  13. Autozoner n civic owner

    Autozoner n civic owner Junior Member

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    ya, im just a retard. thats why checker, pep boys, and autozone have all hired me. also those guys at the society for automotive engineers think im a retard too. that is why they certified me.
     
  14. formby

    formby learning in progress

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  15. phyregod

    phyregod !!YTINASNI

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    You work for shitty parts houses and have a cheap certification.

    I'm not impressed. If you have "autozoner" in your name, and are proud of it, you are fucking retarded. Autozone sells cheap crappy parts.

    I'd put my automotive knowlege against yours any day. Especially after the "back pressure-ring damage" post and your general knowlege of "back pressure" Didn't your "certification" cover that shit???


    Why am I wasting my time on this?? [​IMG]
     
  16. B16RacerN2NR

    B16RacerN2NR Working Hard VIP

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    you are a fucking retard. I used to work for AutoZone...you can quiz me all you want to see if i'm bullshitting. and you do not need to be certified to work there. I got hired the same day they hired another guy for the soul purpose of him being a translator. Yeah he knew about basic maintenence like spark plugs and oil changes but that's as far as it went. I left over a year ago and now that guy is a PSM with the same amount of knowledge that he had when we first started. and you cannot get certified just because you work at autozone. autozone wil give you all the ASE certification books and they'll pay for you to take the test but in no way, shape, or form with they certify your ass for working at AutoZone. Pep Boys pays more than AutoZone ever will at any given position, so why the fuck would go go to Auto Zone unless you got fired from Pep Boys. You think I'm bullshitting about the pay? call these #'s and ask what the going rates are...

    661-942-2775 <---my friend Mike still works at this one, he's a PSM
    661-273-2315
    661-945-1645 <--- I used to work at this one, they'll let you know what the pay rates are..

    Do me a favor, call the # where my friend Mike works, tell him Chris told you to call him and tell him what you think happens with back pressure... he's a PSM, so by your logic, he should feel the ame way, right?? [​IMG]

    To the topic starter... I'm running 2.5 inch crush bent exhaust. and I love it. since it's crush bent, some sections are slightly pinched, so it might just give you that 2.36 inch you're looking for in certain areas of the exhaust.
    My exhaust goes from my header, to a resonator that has a 2.5inch inlet and outlet, straight to my AutoZone Special Cherry Bomb Muffler. and inbetween those is all straight piping. no cat, no test pipe, nothing. and on top of that, it's fairly quiet. It's slightly louder than the RSR ExMag, but not by much.
     
  17. pissedoffsol

    pissedoffsol RETIRED

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  18. hondarin

    hondarin Please enter a value using 50 characters or fewer. VIP

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    well, what's the the stock exhaust size on a CTR? (although, it's not a CTR unless you have high compression pistons) you could bet that once you surpass that size, your power band is only going to get narrower. sure, you may be making more horse power, but your torque curve will suffer below a certain rpm depending on the size of the exhaust.

    hell, i'd say make the exhaust shorter, and go with 2.25" with a dump near the rear subframe, or exit past one of the doors.
     
  19. eg6sir

    eg6sir Supa Mod Moderator VIP

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    wow.. pepboys and autozone will hire a 16 yr old who absolutly no knowledge of cars/parts.. even if all they know how to do is pick there fuckin nose.. so go back to selling your APC bullshit

    i would if i was going full race.. but hey i'm not.. i'm taking my car to the state BAR referee.. and he would shit his pants if he saw something like that.. [​IMG]
     
  20. hondarin

    hondarin Please enter a value using 50 characters or fewer. VIP

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    oh, i just realized you were in california

    i've never been there, but i heard it was even illegal to push the pedal on the right all the way down :p
     
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