[Y2A]

Well for the old motors (B and H series), the biggest piping I've seen people run on the streets is 2.5 inches, and that's with bigger cams and raised compression. With only minor boltons, no bigger than 2.25. But now I see K series powered cars running 2.5 inches with only minor boltons (i/h/e)! Doesn't the low end suffer alot with that big of a piping? So what size exhaust piping should I run? I plan to go all the way with the motor, and have it stay a daily driver(run on 93 gas), still deciding between what CR I wanna upgrade to later on: 11.5:1, 12:1, or 12.5:1. This is a TSX motor by the way.

 

[CrackedUpRacing]

Well for the old motors (B and H series), the biggest piping I've seen people run on the streets is 2.5 inches, and that's with bigger cams and raised compression. With only minor boltons, no bigger than 2.25. But now I see K series powered cars running 2.5 inches with only minor boltons (i/h/e)! Doesn't the low end suffer alot with that big of a piping? So what size exhaust piping should I run? I plan to go all the way with the motor, and have it stay a daily driver(run on 93 gas), still deciding between what CR I wanna upgrade to later on: 11.5:1, 12:1, or 12.5:1. This is a TSX motor by the way.

HEy man. just my opinion but I would just do 2.25 inch. A little back presure goes along way

 

[realek4]

i Have seen People using 3inch on k-series na setups. Havent seen them dynoed yet though.

 

[correll]

HEy man. just my opinion but I would just do 2.25 inch. A little back presure goes along way

:up: :up:

 

[EFIOZ]

Depends on whether you can tune the iVTEC. If you can play with the lobe split then you can sort the scavenge problem you'd find with the bigger exhaust.

 

[TeamPacman]

2.5 inch....2.25 is not going to cut it..

 

[jon v]

I am thinking about going with 3" on my TSX. Should be minor bolt on's in the beginning...

:wink:

 

[JDM2ndGen]

there was someone on H-T with a 3" exhaust on a SI with just minor bolt ons and he made power on the dyno ...

 

[Gravy]

HEy man. just my opinion but I would just do 2.25 inch. A little back presure goes along way

2.25 is nothing. i know for a fact that the nissan vtec motors love 3 inch exhaust. i wouldnt be surprised to see a nice power gain from 3 inch.

 

[DC5RK20A]

Minimum of 60mm(2.36") and depending on what is done with the build 70mm(2.75") is a good size for circuit racing. If you are going all out with a drag setup, I would say jump up to 76mm(3").

 

[allan5oh]

back pressure is *NEVER* a good thing. Velocity is, mainly in the header primarys.

 

[Frog]

When the K -series first came out, Honda-Tuning had an article about exhausts for the K20A2. Although I don't remember the details, I do remember that without any other mods, the stock exhaust size was still the best, when they went bigger they either lost power a bit or remained pretty much the same.

That was with nothing else done to the engine, not even K-Pro.

Just thought that was pretty interesting.

 

[jon v]

I'm looking at putting the Apexi N1 turbo muffler on my K24a2 EK hatch with custom piping...

80mm inlet with a 115mm tip , attached to 3" piping straight back under the gas tank

 

[SHAGGY]

HEy man. just my opinion but I would just do 2.25 inch. A little back presure goes along way

Old muscle car myth.

 

[allan5oh]

Old muscle car myth.

yup kinda like R/S ratio, only thing is R/S ratio seems to have died in v8 camps a while ago(thank GOD)

 

[josh green]

I have a 3" exhaust on my hatch. Its a bit louder than I like driving regualr but I can deal. I have a 2.5" pipe where my car was though but its only about 5" long. My k20a2 swap with hasportheader,3"exhaust, and a very short intake made 180whp and 135 ft.lbs to the wheels.

 

[realek4]

Old muscle car myth.

I have heard this comment from a couple of tuners that Backpressure is a V8 Myth .

 

[josh green]

also that dyno is with k pro type s w/ intake basemap untuned.

 

[B18c5turbo]

I have a 3" exhaust on my hatch. Its a bit louder than I like driving regualr but I can deal. I have a 2.5" pipe where my car was though but its only about 5" long. My k20a2 swap with hasportheader,3"exhaust, and a very short intake made 180whp and 135 ft.lbs to the wheels.

3 inches exhaustmake you lose power for sure during the low end and mid range power, 3 inches its good when your turbo it or you have more than 300 whp then you could go with 3 inches.But i am pretty sure if you had keept your original exhaust as its 2 1/4 and just removed the cat by a test pipe and replaced also the mid pipe center with a 2 1/4 not the 1 3/4 would make you happy even low end and midrange would be powerful across the line than your 2 1/5 or 3 inches

180 whp on a type-s this is the normal amount of hp for this engine.

Adding