exhaust size???

[2s4x0]

i have a non-turbo ka24de. i want to in the future turbo it but for now its not. i was wondering whast size piping for an exhaust to go with. i found the exhaust i want in two sizes 3" & 2.5" with a 2.35" inlet. What should i go with if my car wont be turbo for a while.?

[kerosinek]

3" I have one on my 240 and I love it. It's also a NA KA. If you can, weld a resonator or something on it because 3" is a little loud.

[TooHai4Yah]

3" but i'd highly recommend to get a resonator, n/a ka with 3" is stupid loud for some people

[Phlip]

Three inches, stop asking questions

[9524tee]

2.5 for now... then go 3.

Do it right.

[JDMClifford]

i would wait till you turbo it. what other mods do u have?

[!Zar!]

Originally Posted by 9524tee

2.5 for now... then go 3.

Do it right.

Umm... No.

3" is proven to give gains everywhere over a 2.25".


Buy the 3" and you will be fine. Do it the right/proven way.

[zugoi]

Well if cops are asses where you live then i'd just go with 2.25 but if you dont care then just go 3 inch. I had a straight 3 inch pipe with no resonator on na ka and it was crazy loud.

[2s4x0]

sweet thanks guyz!

[2s4x0]

now that im going with a 3" and you all say its loud. iam going to be running a test pipe with that so does that mean its probably going to be even louder im guessing??? should i even run atest pipe ??

[Dream240]

I take it you dont have smog regulations in your area. If you do, USE A CAT!!! Shit even if you don't, USE A CAT!!

Only assholes run illegally smogged cars and ruin our planet for what....a louder exhaust and black soot on your rear bumper? Trust me your kids will thank you. Plus you get busted with no cat, kiss your car bye-bye. (smog reqd' areas) Here's a cheap solution for a decent cat.

http://cgi.ebay.com/ebaymotors/MAGNA...spagenameZWD1V

EDIT: DELETED MIS-INFO....HAVE A NICE DAY
Also use a silencer to help with the sound.

[koukimonster139]

ye, non turbo your gonna want some back pressure...

but seriously when you go turbo, 3" custom made straight pipe from dp to muff. black soot on bumper is the only way to roll!

[Full-Lock]

Originally Posted by koukimonster139

but seriously when you go turbo, 3" custom made straight pipe from dp to muff. black soot on bumper is the only way to roll!

lol, thats what i have, like exactly. needs a tune..

anyway, go w/ 3in. and you'll be happy. i had a 2.5 in. before and i hated it. it was like a 400 dollar waste of money since i just bought a 3in. one like 2 months later. i didn't even get close to selling the 2.5 for what i originally paid.

just go 3in right off the bat

[!Zar!]

Originally Posted by koukimonster139

ye, non turbo your gonna want some back pressure...

but seriously when you go turbo, 3" custom made straight pipe from dp to muff. black soot on bumper is the only way to roll!

its been dynoed; real, nut butt. so with proof I state that 3" is better na/forced/hamster powered whatever, over a car with 2.25".

[s13gold]

how long or how far away is your turbo kit.....?
if its a long way off...just wait for the turbo..

[ripnbst]

Buying an exhaust thats 3" with a 2.35" inlet isnt gonna help you when you go to turbo it. When you go boosted you're gonna want 3" the whole way back. I'd say go with the 2.5" now save the extra money a 3" will cost and save it for the turbo kit later. Even if you did run the 3" now, you would have to replace it again when you went Turbo.

[!Zar!]

Originally Posted by ripnbst

Buying an exhaust thats 3" with a 2.35" inlet isnt gonna help you when you go to turbo it. When you go boosted you're gonna want 3" the whole way back. I'd say go with the 2.5" now save the extra money a 3" will cost and save it for the turbo kit later. Even if you did run the 3" now, you would have to replace it again when you went Turbo.

Umm. Please explain why a 3" on an na and 3" on a force induced would be different? Like I checked it was the exact same.

It wouldn't be beneficial for him to purchase an exhaust now, hope he can sell it later then purchase ANOTHER exhaust.

Just get the 3" now.

But on the contrair, there isn't really a huge need for exhaust. It's not like your car will explode with turbo and stock exhaust around stock boost.

So much super street misinformation around here...

[HalveBlue]

Depending on the engine, an NA motor will sometimes power losses from increasing exhaust piping diameter; the added back pressure removes exhaust gasses from the combustion chamger more efficiently.

Of course, like I said before, this depends on the type of engine, what accessories are installed, etc.

If you're planning on doing a turbo swap down the road anyway, go ahead an just get a 3", because in the long run you'll want one anyway.

[Dream240]

EDIT: deleted due to my retarded-ness......

[!Zar!]

The biggest differences with back pressure is not the exhaust but the header design. Like a 4-1 or a 4-2-1.

The 4-2-1 would be best for our cars unless you have a huge turbo and only want highend.

THEN there is the downpipe. Which I haven't even see him mention. So it's still useless.

KA 3" exhaust before/after dyno
That thread has more information regarding the whole 2.25 vs 3 debate...

[Flybert]

Dream240, don't respond to this thread anymore because it's obvious that you don't know what you are talking about.

3" makes more power on NA then 2.25". It's dyno proven. Alex chang did back to back dynos with both diameter exhausts on a KA. 2.4L KA's push a lot of exhaust and love 3" exhausts. Maybe you are used to driving hondas or other small displacement I4's and all your information comes from that camp but it has been proven that it doesn't apply to the KA.

[white97s14]

3" enough said

[steve shadows]

Originally Posted by !Zar!

Umm... No.

3" is proven to give gains everywhere over a 2.25".


Buy the 3" and you will be fine. Do it the right/proven way.

He said 2.5

And its not everywhere you do lose torque in places IMO I would rather have it with a KA.

[steve shadows]

Originally Posted by Flybert

Dream240, don't respond to this thread anymore because it's obvious that you don't know what you are talking about.

3" makes more power on NA then 2.5". It's dyno proven. Alex chang did back to back dynos with both diameter exhausts on a KA. 2.4L KA's push a lot of exhaust and love 3" exhausts. Maybe you are used to driving hondas or other small displacement I4's and all your information comes from that camp but it has been proven that it doesn't apply to the KA.

He did it on a KA24DE and that does make a difference.

The CFM rate of the dual cam is higher. Torque loss is greater with single cam engine. :hammer:

But for the guy above (original poster) If you really are seriously going turbo go 3 inch now. It will just be loud.

Anyone have the dyno graphs? from Alex? I think he posted them on Freshalloy a long time ago and I picked them apart then too iirc.

[Flybert]

Originally Posted by steve shadows

He did it on a KA24DE and that does make a difference.

The CFM rate of the dual cam is higher. Torque loss is greater with single cam engine. :hammer:

But for the guy above (original poster) If you really are seriously going turbo go 3 inch now. It will just be loud.

Anyone have the dyno graphs? from Alex? I think he posted them on Freshalloy a long time ago and I picked them apart then too iirc.

Read the original post. We are talking about dual cams here.

Here's alex chang's dyno chart of a 3" exhaust vs. stock for everyone to see. Go 3" unless you want something a little quieter. That's all that it comes down to. And if you turbo a KA, you can possibly look into an exhaust that is bigger than 3". Pretty sure Apexi GT spec exhaust would work great with turbo KA.

http://forums2.freshalloy.com/showth...+proracer+dyno

[markyboi]

get a 2.5 inch....then in a month, buy a 3 inch exhaust...and sell me the 2.5 inch for a 100 bux!

[Dream240]

Originally Posted by Flybert

Dream240, don't respond to this thread anymore because it's obvious that you don't know what you are talking about.

3" makes more power on NA then 2.25". It's dyno proven. Alex chang did back to back dynos with both diameter exhausts on a KA. 2.4L KA's push a lot of exhaust and love 3" exhausts. Maybe you are used to driving hondas or other small displacement I4's and all your information comes from that camp but it has been proven that it doesn't apply to the KA.

You're absolutely right. I guess I dont know what I'm talking about. I did some more research and from what I had learned waaaaay back in the day was referring to exhausts LARGER than 3" being more hurtfull to NA midrange power. I will delete my previous post to avoid future confusion. So well said sir....I concede the knowledge crown to you

As far as exhaust noise...I am running a 3 inch cat-back with silencer and it's crazy loud above 3000 rpms. So really noise will be your only concern.

[steve shadows]

oook But i think that dyno from Alex is comparing STOCKexaust to the upgraded racing exaust.

I am talking about comparing a 2.5 inch straight pipe with a Dynomax muffler for example to a 3 inch turbo exaust like the N1 or 5 Ziggen.

Its all water under bridge as I said, In referring to the Original Poster if he is going to go turbo, it will just be loud in the mean time as other have noted.

[lilredstiffy]

3" at least on ka or ka-t or sr or ca

anything smaller is outdated and makes less power

[aznpoopy]

Originally Posted by steve shadows

oook But i think that dyno from Alex is comparing STOCKexaust to the upgraded racing exaust.

I am talking about comparing a 2.5 inch straight pipe with a Dynomax muffler for example to a 3 inch turbo exaust like the N1 or 5 Ziggen.

Its all water under bridge as I said, In referring to the Original Poster if he is going to go turbo, it will just be loud in the mean time as other have noted.

+1

3" may show gains over the whole range vs. stock but that doesn't mean it's ideal for n/a ka24de. there's more to exhausts than backpressure... you also want to keep the exhaust stream hot (colder = denser aka heavier aka harder to move) and the flow velocity quick (for better scavenging). too big can adversely affect both of these factors. just b/c the backpressure myth has been debunked doesn't mean it's impossible to go too big.

without more information though, its problematic to make blanket statements as to which diameter is best. there are differences besides piping diameter which can potentially affect numbers you get on a dyno...

that discussion aside, 3" with turbo plans in the future is perfectly fine.