2 1/4 or 2 1/2?

just wondering whats better, 2 1/4 inch exhaust or 2 1/2 inch exhaust for a ZC? i wanna help it breath a bit better and flow better too and i can get a good deal on exhaust right now so whats better? :)

For N/A, you want backpressure. I would go 2" or 2 1/4"

as long as you dont plan on putting a turbo or nething on there the largest u should go is 2 1/4, thats what i have on mine and it makes a huge difference over the stock.

2 1/4 u need that backpressure--- :bananadie

please stop spreading misinformation.

you do not EVER need back pressure. BACK PRESSURE IS BAD ALWAYS. 100% of the time. not 50% of the time, 10% of the time, 99% of the time. BACK PRESSURE IS BAD AND YOU DO NOT WANT IT.

please learn what the hell you're talking about before you go spouting off some bullshit that redneck bob told you about his camaro mufflers.

1phatcx: to answer your question, i would go with a 2.25" mandrel bent exhaust, and if you cant get that, then 2.25 crush bent

you man i got a DOHC ZC with 2.5 piping and it work well. i am planing to turbo it this winter. i say get 2.5 :D

2.25!!!

D series WAHHHHH!

sounds like 2.25 it is :) i can get a 10 foot straight length of pipe for 24 bucks and those mandrel bent u pipes like JC whitney sells for 25 bux :) hehe cheap free flowing exhaust here i come! :)

I'm gonna turbo my car but have no money currently, and hell, its only like 50 - 60 bucks i'm spending so i figure why not? same price for the 2.5 as well, maybe a buck or 2 more tho no biggie

if you're going to turbo it in the future, put atleast a 2.5"

please stop spreading misinformation.

you do not EVER need back pressure. BACK PRESSURE IS BAD ALWAYS. 100% of the time. not 50% of the time, 10% of the time, 99% of the time. BACK PRESSURE IS BAD AND YOU DO NOT WANT IT.

please learn what the hell you're talking about before you go spouting off some bullshit that redneck bob told you about his camaro mufflers.

1phatcx: to answer your question, i would go with a 2.25" mandrel bent exhaust, and if you cant get that, then 2.25 crush bent

You say you dont need backpressure, but then agree with the size of piping? Backpressure is needed for n/a power.

[QUOTE=91civicDXdude]
"you do not EVER need back pressure. BACK PRESSURE IS BAD ALWAYS. 100% of the time. not 50% of the time, 10% of the time, 99% of the time. BACK PRESSURE IS BAD AND YOU DO NOT WANT IT.
please learn what the hell you're talking about before you go spouting off some bullshit that redneck bob told you about his camaro mufflers."

hey dude you should take your own advice, you really think you don't need backpressure? loosen or unbolt your exhaust manifold at the head and then fire it up. then stop spreading your misinformation.

the only time backpressure isn`t needed is in a high powered race setup or something going for a land speed record. a civic that doesn't have turbo/supercharger will need *some* bp to idle and run smoothly. unless you plan to drag race your car with serious mods you should keep at least a high flow performance resonator/muffler on a straight 2 inch whatever pipe to keep it street legal, possibly a cat if emissions are a problem...

without back pressure your cars dies at idol under 2000rpm. so put a 3 inch exhaust on your CIVIC (not CAMARO) and sit at a light in traffic for a few minutes and see how long you keep that engine running dork knob....

civic tuning 101- 2 and a 1/4 inch pipe is the HONDA recomended sized pipe used for NON-ASPIRATED vehicles (see definition below) for advanced tuning. pulling numbers out of your arse and actually doing research and talking to HONDA certified mechanics are two different things. ANY d series engine should have 2 1/4. B series or larger is recomended 2 1/2 inch pipe do to the larger output. large amounts of back pressure IS bad but you do need SOME b/p.

NON-ASPIRATED- a non turbo or non supercharged vehicle (most of our civics)


-side note- you are going to need at least 14 feet of pipe to replace to the stock position and at least 11 to retrofit the exhaust to the right side. i know because ive done both and measured it out.

you do not need backpressure. say it with me. YOU DO NOT NEED BACKPRESSURE.

what you DO need is exhaust velocity. the size of the piping dictates the exhaust velocity of any given setup. too big of a pipe makes the engines exhaust have little to no exhaust scavenging at lower rpm, which is why i suggest 2.25" piping. I run 2.5" exhaust on my car; my header collector is 2.5". Honda must not know about "needing backpressure" and 2.25" exhaust becuase their integra type R has a 2.5" collector on the header.

btw, i've run my car open header MANY times, and the idle is fine. OMFG MY CAR MUST BE MAGIC! IT WONT IDLE WITHOUT BACKPRESSURE!!@#@@

backpressure is a force acting against the pistons effort to expell exhaust gas, which in turn leads to loss of power. Just like removing friction from the engine will free horsepower, removing all restriction (i.e. BACKPRESSURE) will free up horsepower.

civic tuning 101- 2 and a 1/4 inch pipe is the HONDA recomended sized pipe used for NON-ASPIRATED vehicles
Non Aspirated huh? you might mean NATURALLY aspirated, because non aspirated would mean the engine takes in *NO* air. but maybe you'd know this if you didnt pull numbers out of your arse and actually have common sense. dumbass.

Please do ME a favor and learn what the hell you're talking about before trying to act smart newbie.

Go for 2.25" if you are n/a. 2.5" if you are going to run a turbo or a all motor beast.

btw, i've run my car open header MANY times, and the idle is fine. OMFG MY CAR MUST BE MAGIC! IT WONT IDLE WITHOUT BACKPRESSURE!!@#@@

=.

ok i'm not here to flame or anything, but that guy was talking about unbolting AT the head. So your tellin me that your car will start up with out a header period? From what i'm reading in your post, i'm guessing your just didn't have the header bolted on to the cat, which would be running open header.

without back pressure your cars dies at idol under 2000rpm. so put a 3 inch exhaust on your CIVIC (not CAMARO) and sit at a light in traffic for a few minutes and see how long you keep that engine running dork knob....

that's funny, i took my turbo off and put on a header for awhile, and kept my 3" exhaust. My car ran fine, though it was a little loud.

civic tuning 101- 2 and a 1/4 inch pipe is the HONDA recomended sized pipe used for NON-ASPIRATED vehicles (see definition below) for advanced tuning. pulling numbers out of your arse and actually doing research and talking to HONDA certified mechanics are two different things.

I work for honda, and I say go with 2.25 for VERY mild N/A setups (ex: keeping stock airbox & manifold per SCCA). 2.5" for N/A, and 3" for forced induction.

I built my cat back (which exits on the right hand side) with one 4 ft section, 2 u-bends, and one 18" section. this was for a civic 3d BTW.

......backpressure is restrictions in the exhaust system that slow the exit of exhaust gases from the combustion chamber.....

Go for 2.25" if you are n/a. 2.5" if you are going to run a turbo or a all motor beast.


like i stated above, i'm turboing it later on down the road when i get everything i need, i dont have it yet so i'm gonna run 2.25 because i can do either set-up for 60 bucks anyways

since the stock exhaust has a resonator, can i just toss a cherry bomb in that location anyways? or no point? because i dont want it to be annoyingly loud because i think i might take the cat off and put on a test pipe, dunno yet

I work for honda, and I say go with 2.25 for VERY mild N/A setups (ex: keeping stock airbox & manifold per SCCA). 2.5" for N/A, and 3" for forced induction.

I built my cat back (which exits on the right hand side) with one 4 ft section, 2 u-bends, and one 18" section. this was for a civic 3d BTW.


alright, so since i only have an intake and header i'm assuming thats classified as a MILD N/A set-up correct? :) so yea for sure i'll do it with 2.25 because i dont wanna have 2.5 if i'm not gonna have a turbo for awhile, or will that .25 make a world of difference? cuz if its not gonna hurt the car any adding an extra .25 inch to the exhuast size then i might as well do 2.5 right? jeez, i'm confused lol, cuz this is my set-up

DOHC ZC with Intake and Header, Mild P&P (port match) and bored out the throttle body about 5mm, now what should i use :) lol

If you're going turbo later go with 2.5" pipe. Are you trying to stay legal? Use a high flow cat. I have a 2.5" cat with 2" pipe and 2.25" axle back loop and my car is N/A with pulleys, cam, cg, CAI, header, etc. I would agree with civicdxdude 100% and krustindumm but being that I'm at 1000 ft. above sea level most of the time my car sorta runs a bit better in the mountains with some pressure. I've ran the whole 2.5" exhaust and I pretty much had to floor it up and down the hills. I prefer to save my fuel. I may switch out the high flow and go with just a resonator 2.25" piping total with dynomax in the future cuz there isn't emissions here in SC, but I'm a bit environmentally conscious (just a little) so I like the cat. Anyway, I'm not saying back pressure is good, but living in the mountains and trying a full free flow and other things I personally know what works best not from listening to "redneck bob" so if you don't believe....

i have run open header many times, but as a matter of fact, i have started my car up with no exhaust manifold on it at all. It runs, and shoots 4 bad ass flames out the front of the head, but i wouldn't recommend it. and i wasnt driving it aorund, just started it up to see what would happen :O

I've tried just about everything once when it comes to cars, just becuase my personality is a experimentative one.

yeah, I had to experiment too, cuz redneck bob wasn't giving me any answers... back pressure good? back pressure bad? the honda guy said, "I'm a Nascar fan myself"... I wouldn't try starting the car without an exhaust manifold though... I've already had one fire :wink:

well yea i fired up the ZC open header the first like 9 times and holy hell it was loud! haha expectially sitting at 3 grand :)

so even if i dont have it turbo'd for another year or 2 u guys suggest 2.5 from the cat back? or test pipe back (dunno what i'm doin with that yet)

since the stock exhaust has a resonator, can i just toss a cherry bomb in that location anyways? or no point? because i dont want it to be annoyingly loud because i think i might take the cat off and put on a test pipe, dunno yet

A cherry bomb works excellent as a resonator, I personally have ~23" cherry bomb as a resonator on my setup, it keeps my exhaust nice and quiet.

A cherry bomb works excellent as a resonator, I personally have ~23" cherry bomb as a resonator on my setup, it keeps my exhaust nice and quiet.


sweet! :D
now the exhaust total is up to 80 bucks lol :p

I'm still confused tho between 2.25 and 2.5, i havent decided if i want all motor or forced induction yet, i want a turbo but its gonna be expensive hmmmm :(

fuck, i dunno, i think i might say fuck it and get a 2.25 for now untill i make up my mind on turbo or n/a

I think im goin 3" =)

i have run open header many times, but as a matter of fact, i have started my car up with no exhaust manifold on it at all. It runs, and shoots 4 bad ass flames out the front of the head, but i wouldn't recommend it. and i wasnt driving it aorund, just started it up to see what would happen :O

I've tried just about everything once when it comes to cars, just becuase my personality is a experimentative one.

i wouldnt reccomend running a car with no exhaust manifold only because i dont like burnt valve but hey wut do i know?

i wouldnt reccomend running a car with no exhaust manifold only because i dont like burnt valve but hey wut do i know?

i dont recommend it either, but i wanted to see what would happen so i did it.

i dont recommend it either, but i wanted to see what would happen so i did it.

LOL

umm as far as exhaust size....i have a 91 standard hatch with 2.25 inch all the way back to cat with a magnaflow muffler. its the 1.5 with the 4 speed that everyone complains cuz it cant clime hills or keep up with traffic. but since the exhaust i have no problems climbing hills and keeping up with traffic is a lot easier.

well since i'm pushing prolly double the power of the d15b1 (i'm assuming thats what u have hence the 4 speed) but yea, i'll go with the 2.5 inch exhaust then and do that instead :)

I have 2.25 crushed bent now, im thinkin if i get 2.5 crushed, this would almost give me the best of both with 2.25 at the bends....or maybe 3" crushed to give me almost a 2.5 at the bends. I also have the 3" iceman cold air intake and a header with a 2.25 inlet muffler for a V8. I like it but feel i could use some more space(flow) at high RPM's. And can u over advance your timing with the destributer?

i already went with the 2.5, paid 35 bucks total for it for the setup, my buddy gave me the left over pipe from his car when we did his impala and all i bought was a cherry bomb :)

all in all, all it takes is any length of section lesser then the pipe you installed,
will create backpressure.
One inch of the original pipe anywhere will create same backpressure,
as the whole orignial system.

this thread is kinda old....

I know,
there was a mechanic here,telling me to write stuff on here,
but o well....

Well you also have to remember that every 90 degree bend(mandrel) is equal to 10 feet of pipe which in its self is creating backpressure.

when i first started working on hondas i was always told never go any bigger then 2.25 or you will get to much b/p, i know if you have turbo big is better hell go 3inch if you want. but i never go bigger then 2.25 on all my hondas.i have that on my integra now, it b/f every time i shift but every integra guy i talk to say's there's does that to.


:ylsuper:

when i first started working on hondas i was always told never go any bigger then 2.25 or you will get to much b/p, i know if you have turbo big is better hell go 3inch if you want. but i never go bigger then 2.25 on all my hondas.i have that on my integra now, it b/f every time i shift but every integra guy i talk to say's there's does that to.


:ylsuper:


i wouldnt mind havin mine backfire when i shift that would be cool, hell with the kind of gas i run, i'm sure u'd see a nice flame too :)

i have 2.5" on mine have had it for 4 years i like it but go with what you like :iceslolan