2.25" or 2.50" piping?

[91civicRacer]

Which size piping would be best, 2.25 or 2.50? I'm getting custom mandrel bent piping but I can't decide which size I should go with.
Got a D16A6 powerplant but soon to be swapped for a B16A :ylsuper

[GTA]

2.25 is all you need for a N/A engine.

[mellowboy]

yeh u dont need anything bigger than 2.25 unless ur goin turbo

[Tony]

well that was easy. Yea unless your runnin some boost, you only want 2.25", you will loose too much back pressure. My friends prelude has 2.5" and its loosing too much back pressure.

[kicker1_solo]

I just ordered a muffler with a 2.5" inlet so I'll be running 2.5" piping on my N/A accord

[91civicDXdude]

there is no such thing as losing too much backpressure. I belive you are thinking about exhaust size vs. exhaust velocity. a bigger pipe is going to give you more high rpm power because more exhaust gas can escape at higher rpm's with a larger pipe, but you are going to lose that low rpm torque... well you dont LOSE it actually it just moves upward in the powerband.

[Zippy]

Originally posted by 91civicDXdude
there is no such thing as losing too much backpressure. I belive you are thinking about exhaust size vs. exhaust velocity. a bigger pipe is going to give you more high rpm power because more exhaust gas can escape at higher rpm's with a larger pipe, but you are going to lose that low rpm torque... well you dont LOSE it actually it just moves upward in the powerband.

Thank you jesus. Someone who knows a thing about exhaust dynamics

[Zippy]

Oh yeah, I dont exactly believe in "custom" exhausts from an exhaust shop.

btw...the backpressure section on the page below is something you all need to read. go down a few scrolls.

I believe in correctly engineered ones i.e. Tanabe, GReddy, HKS, etc...

http://www.teammatrix.com.my/CarMods/exhaust_1.html

[Tony]

well the reason i said you would loose too much back pressure is that is what I have always been told.

[SiZ]

With a B16, definatley go with 2.5".

I love my 2.5".

[EF You]

yeah im so glad someone beat me to it. you lose delta pressure, which is the measure of exhaust velocity, not back pressure, which is the measure of resistance . well you actually lose back pressure too, but you wanna do that anyway. ways to lose back pressure are getting rid of as many restrictions like bends in the pipe, size changes, and things like the cat convertor and muffler. ways to maintain delta pressure are almost the same, you wanna have a consistent flow throughout, and you want it to be a different size depending on where you want your torque in the powerband. i personally like adding to my VTEC range, cause i like playing catchup and then blowing by people (they think im squeezing when that happens).


you will notice your current motor has a lil less punch when you go with 2.5, but i think when you throw a b16 in there you will like it a bit more when VTEC comes around

[Jmunk]

All N/A D-series motors don't need anything over 2.25", i always do 2.25". A B, H, F series i would use 2.25 or 2.50".

[Tony]

Well thanks for clearing that up guys. I am a little bit smart now , still a long ways to go

[tanas]

Recomendations for a dohc ZC with hopes of a turbo.

My friend has a mechanic who will put on an exhaust system for like $100. So I'd like to know what size I should think about. (He has a 3" pipe on his 240sx and is very happy with it)

[Zippy]

Originally posted by Tony
Well thanks for clearing that up guys. I am a little bit smart now , still a long ways to go

Dont worry man. Hang around cars as much as you can...you will learn much... more than you ever thought possible.