todahead

i'm searching for an exhaust upgrade i own a dc2 swap on ek chassis .
current mods are 3.5'' intake with flow stack,rmf narrow header,decat and a 2.25'' hks silent cat back exhaust.engine internals are stock.
soon i'll tune using a chipped p28 and i need a new exhaust since hks has some bends etc.

i found here some people suggest 3'' exhausts even for stock b16's
but i haven't seen any dyno runs or any comparison between a smaller diameter exhaust.
with my set up i will have some power gains or just only a louder ex system?
cheers !

DDTECH

3'' inch ..period.

If you'd search correctly you'd find a ton..

https://honda-tech.com/forums/showth...%27%27+exhaust
https://honda-tech.com/forums/showth...%27%27+exhaust
https://honda-tech.com/forums/showth...%27%27+exhaust
https://honda-tech.com/forums/showth...%27%27+exhaust
https://honda-tech.com/forums/showth...%27%27+exhaust


there's a ton more, you dont need a dyno to see, 3'' exhaust should be a minimal for any all motor setup, if its a d series or b series or f or k it shouldn't matter, its been proven time and time again that a 3'' is better.

dntnedvtec

I haz a 3" exhauze.

Its loud, but when blazing down the strip, who cares? But for DD, not a good thing.

todahead

why is a bad thought if you use big resonators it can be good even for cops ears ...

todahead

hmmm i think i can trust you on that most ppl here use 2.5'' witch actually is a true 60mm (ID) on b18 i'll go for a full custom 3'' exhaust thanks for the search btw !

88Hatchy

No need for a custom exhaust. Thermal R&D makes a 3" exhaust for all our cars.

89LSED

3" exhaust on a stock internal NA motor?

Seem a little to big for me. Dont you need soooome back pressure?

DDTECH

Nope

FlewByU352

It is impossible to get through to 98% of people that you do not need back pressure. Ive tried to explain my 100+ pages of reading and research and they say no you definately need back pressure. Yeah ok (rolls eyes). I went with 2.5" which is actually 2.36" because its not a Vibrant (which makes the most beautiful exhaust lol and is true size ID). I used this over 3" simply due to it is a DD more so than a track car. It does see the track but 2.5" was more appealing. I think the only way I would go 3" is boost but I like NA so it would be a full time track car.

C_Rock77

Only if you believe the backpressure fairy will put some WHP under your pillow at night.

3" exhaust has been shown to produce power in a VARIETY of builds...in B16s where people THOUGHT they wouldn't, it picked up power.

Like many have said, they go with 2.5" as a compromise.

flipmoderacing1

I put a 3'' on my dsm and yeah its loud at lower rpms n when ur runnin wop, but there's no harm in it. I mean as long as u use a hi flow cat n dont mind loosin some mpgs..... It wont b as bad on ur car as it was on mine. I went from 29 mpg to like 13, but i've also got 532 cc injectors usin a fuel management system. it wont hurt the engine at all n might give u a max hp gain of 15 hp or so. But it will def sound nice! Just beware of really strict residential areas! he he

bonesx0x2x4x

i had a 2.5" on my b18 teggy for a while...moved to a 3" recently...alot louder better performance by a hair and deff good if your thinkin bout a turbo in the future

F THE POLICE!

neverstop

this whole argument is dumb..... do race cars run tiny exhaust for "back pressure" or does nearly every fast drag car run open header?

done.

00Red_SiR

lol...

todahead

learned :velocity is good
back pressure is bad
so the bigger is better on top of all is open headers thanks!!

fv8s

haha. lesson learned

89LSED

Well i think then im gonna suck up and do it!

I just made my own 2.5 system on my wagon.

Im gonna get a baseline done at Midnight, then build myself an exact same system out of 3. Run it again

DVDr

iTrader: (2)

Thats great for comparison .

going to dyno ?

89LSED

yup.
cant do it right yet, because my motor is blown... but as soon as midnight builds me a new one then ill get some numbers

VtecCarHauler

3 inch all the way. I remember ppl saying 2.5 was to big back in the days.

DDTECH

Thats because people were uneducated.

2k.civic.si

i switched to 3"....and im never looking back...it made more power everywhere

mrbsponge

we have countless dynos of cars going from small exhausts to 3in, i wouldnt put anything else on a gsr or larger nowadays as everyone will eventually want to step up thier motors, i dont see many people adding a couple parts and quiting these days.

a solid muffler, and or resonator will do its job to keep the otne down and sound nice

rhymeshark916

"89lsed", make me a 2.5" piping with one big resonator for my 92 h/b.

Ohio

im having a custom 3 inch done too, Just got my KiddRacing Header.. Now its time to start looking at 22 inch long magnaflow mufflers for my Custom 3 inch side exit exhaust on my DB8