3'' exhaust vs 2.5'' on b18c any dyno's??
 

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 !

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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.

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

I haz a 3" exhauze.

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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 !

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

3" exhaust on a stock internal NA motor?

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

Nope

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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.

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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.

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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!:)

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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.

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

lol...

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

haha. lesson learned

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

Thats great for comparison .

going to dyno ?

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

Thats because people were uneducated.

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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

Re: 3'' exhaust vs 2.5'' on b18c any dyno's??
 

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