ttang

wanted to ask you NA guys (hopefully somebody has done this before):

I have a built 2.4L (F24C) and am currently running the Spoon N1 exhaust, which is about a 60.5mm (62mm exit diameter), and it was mentioned I might benefit from a larger diameter exhaust. Also, I'm running the Spoon test pipe, but if i go to a 70mm, should i get a larger test pipe?

Does the theory of a 60mm, providing low-mid end power vs. 70mm providing mid-high end power still hold true for a built 2.4L NA?

Short of testing with 2 exhausts on the same day on the same dyno, I'm not sure if it will make a difference. I'm also running a Hondata, so I think my tuner could potentially tune the car differently for each exhaust, so bottom line is, which exhaust will give more power? Or will the 60mm vs 70mm theory hold true...

other mods that might affect your responses:
- Hondata KPro
- snorkel intake (soon to be J's intake)
- J's SPL header

thanks in advance!

H22toF20

Your theory is wrong. Go with a 3" and enjoy more power EVERYWHERE in the powerband.

A factory internal H22 will make 6-8 lbs of torque threw out the powerband, with a 3" over 2.5". So a 3" should make great gains over a 2.25" on an S2k. 3" has been proven time and time again on stock internal K20/24's, H22's, B16/18's ect. I'll keep preaching this, untill people stop posting misinformation.

EDIT Here's a dyno of the new Challenge 3" over an Apex-i World sports exhaust. The gains are made on a factory computer. Just imagine it both set-up's were tuned.
https://www.s2ki.com/forums/index.php?showtopic=802580

b.r.i.a.n.

3 inch single > *

yes even on a simple bolt on n/a setup

suzuka-blue-s2k

The new HKS 75mm single isnt that much. Looks awesome too.

siik_ap2

ive had a 3" on all my cars including b16 swapped eg, h22 swapped eg, h2b swapped eg, h23 non vtec prelude, and last but not least my s2...3" especially on a bigger motor will perfeorm best overall..

GyozA

Considering you have a 2.4L I would suggest a 3" with a matching TP. I think InlinePro had one at one point in time. Send a message to one of the other guys with a 2.4L and see what they think.

EVAN&MONICA

With the J's SPL I think a 70mm with good flow would be fine but a 3" might be better, either way I wouldnt suggest anything smaller than a 70mm (since the outlet on the header is 70mm)

ttang

hahah i love your simple response.

Only a guy from the DOS days would understand that now i think.. or command line users!

ttang

thanks for all your advice guys.

i didn't realize until i checked that 70mm isn't 3", it's 2.75"!

i'm definitely going for a 3" then..

my tuner has proposed to build me a custom aluminum exhaust, so i might go that route instead... any thoughts about that?

Mike21

Do it. 3" all the way.