Exhaust on a Civic.

[4jacks]

Whazzup Ppls !

Heres the break down. Just ordered my muffler. Its a nice big shiny free flow, got it off Ebay. But I wanna put some noise on my ride, so I'm getting the pipes custom bent , I wanna go 3" pipe all the way back to the Cat.

SCC had an article testing a 1.6L w/ 2" , 2.25", and 2.5" course 2.5" got the best results, so I figure F*** It .. I'll get 3"

While Doing this I was planning on buying a Cheap Catalytic Converter from a Junk yard and bore it out. So its the just like a Straight Pipe application, with a free flow Muffler. Except when a mechanic or someone looks under it, it appears to have a legit Catalytic Converter.

While Crawling under my car today I noticed something VERY disturbing !!! the Cat is part of the DownPipe !?!?!?! WTF is up with that !! that ruins all my plans. I dont wanna bore out MY CAT, incase i need to put it back on, for inspection or something. And getting a cheap CAT and downpipe that fits is going to be rough.

So here's the Million Dollar Question.

Will Any Other Civic's Downpipe and Cat Fit My 02 HX ???

Like will a down pipe and cat from an Older Civic Fit on my car, And if so What Years ??? and Models ???

Thanks for reading my Long Lame Post !?!?!

[94_AcCoRd_EX]

Good luck with the new muffler. 3" is too big though, but its up to you. 2.5" max is that way to go unless you're running a turbo. Just because 2.5" gave better performance than 2.25" doesn't mean 4 will be better than 3, etc.

[4jacks]

Whether 3" was too big was my kinda hidden question.
I've heard that the theory " An exhuast needs Backpressure" is just crap.
If this is true then the best pipe size would kinda cap off, like you would get the same advantage out of a 4" as you would a 3" if you really only needed 2.75"

A larger exhuast pipe can't lose potention gain , can it ?????

I guess it would all boiler down to the "Back Pressure" Idea.

Plus my exhaust has a 2.5" inlet, I was just trying to prevent as much back pressure as possible.

Another thing is that the 2.5" pipe was a BIG increase over the 2.25" ....

[94_AcCoRd_EX]

You know, I've read a lot of stuff on the backpressure thing, and everybody disagrees. I really don't know what the final answer is on that, but I do know what most import people do. Seems like 2.25-2.5 for NA and 3ish for FI. If you do go with 3", let us know how it works out... are you thinking of going FI in the future?

4Jacks...they were selling "racing downpipe's" for our cars on e-bay a couple weeks ago for around $150. I looked but there are none on there right now. I would say just keep checking back.

BTW, I wouldn't go over 2.5"...anything bigger than that is just too big unless you're running some sort of forced induction.

[Whtehnda93DXSdn]

Going over 2.5 is really only if you throw a Turbo/SC on there.....Would be over kill if you do. But if you did decide to go w/ 3 let us know how it performs.
I bet thoght you will cheat yourself a few ponies going w/ a 3 though.

Good luck w/ the choise you make and let us know....

[AzCivic]

(Once again)
Backpressure is NOT good for any engine! The reason for the smaller diameter piping for a naturally aspirated engine is to help keep up exhaust velocity which helps evacuate the exhaust gases in the low RPM's but in the higher RPM's bigger is better cause you have enough exhaust flow to make use of the extra room, so for N/A you kinda have to make a comprimise but for turbo the bigger the better. But yeah 2 1/4- 2 1/2 is a good choice.

[4jacks]

Originally posted by Juggaman
4Jacks...they were selling "racing downpipe's" for our cars on e-bay a couple weeks ago for around $150. I looked but there are none on there right now. I would say just keep checking back.

I saw those... but was a little unwilling to spend 150 bones on something that was big and shiny and UNSEEN ...
that why I was planning on spending $10 at the junk yard.

I did recently find out that some after market Headers for our cars have the CAT extentsion. So I might wait and get that.

Originally posted by AzCivic
But yeah 2 1/4- 2 1/2 is a good choice.

2.25" is NOT a good choice ... a letter into Sport Compact Car, ran a dyno on a 1.6L Geo Storm w/ 2.25" and 2.5" and thier was a drastic increase in the 2.5" SCC may 02 V. 14 No 5 .. Page 26


As for staying All motor or Going FI .... In the Far future I may Add Nitrous. a 75hp Shot... I would rarely use it... just for that punk sitting next to me at the Light.

This would come after ALL my Cosmetic Mods though .. I'm Going ALL Show little Go

Talking to a muffler shop getting a quote.... One shop person stated that going with 3" may be a bad idea due to the fact that it would hang really low and scrap on all the speed bumps and if I ever wanted to lower my car , FORGET IT ...

This was a Good point.