Best size exhaust and manifold for B18C4?

[Dexter]

I'm planning on completely renewing my exhaust from the manifold all the way to the back box, but i'm not sure about some issues yet. This is my plan at the moment:

4-2-1 manifold from TSS Tuning, high-flow cat, high-flow mid muffler, 2.25" custom exhaust, Magnaflow back box.

I'm thinking about getting a 2,25" exhaust as i've heard that with a 2,5" you might end up losing high end power, unless the engine is heavily modified. So what's the truth? At the moment I'm planning on minor engine mods, aiming for 190-200hp perhaps.

Second question is about the manifold. I'm having a hard time deciding if i should upgrade the oem 4-1 to a better one or to replace it with a 4-2-1. I'd like to gain a bit of torque since the B18C4 doesn't go anywhere without the v-tec, but then again i don't want to lose too much top end horsepower. Any experiences or suggestions about this?

The only B18C4-specific exhaust manifold i've found is by TSS Tuning, but i'm sure other ones fit as well. Does anyone know if all B18-engines can fit the same exhaust manifolds?

Cheers!

[Jason.s]

You`re probably more likely to gain high end power with a 2.5" system but possibly lose a tiny bit from down low. Personally i go for 4-2-1 everytime. The old theory is 4-1 is like mid-high power gains and 4-2-1 is more low-mid. Cant remember if it was ever exactly true. I`ve seen on some sites where it has been tested and neither of them have been clear cut but then it depends on the manifold and the design other than the 4-1/4-2-1 design. Also its generally known that the manifold frees up the most power in the exhaust system so you would see/feel the biggest difference from replacing that than just a catback or a sportscat

Other B18 manifolds will fit yes, its just the B16 items that could cause you trouble due to the B18 being taller than the B16 to accommodate the extra stroke length.

[bepilot]

I'm having the same questions as you Dexter, and that's what my fellow Honda friends tell to me:

The best mani for B-series remains the 4-1 concept, this also looks to be the option of your website TSS - seems they are wrong by stating it is a 4-2-1 as the ref is FK120 and this is the same mani as the DC2, also 4-1 concept.

http://www.tss-tuning.de/onlineshop/auspuffanlagen-faecher.php

If you plan to spend so much money on the manifold, I would suggest the 98spec ITR replica:

http://www.yonaka.com/Yonaka_Headers_4_1_ITR_Header_p/ymeh001.htm

Tegiwa sells those in the SS-version...

http://cgi.ebay.co.uk/Yonaka-4-1-Integra-ITR-Header-Manifold-Stainless-Steel-/180476183346

There are plenty of cheaper options, just put "gsr header" on ebay and you should find some more - but beware that sellers don't always make a difference with B16-B18 as Jason.s says - this pictures it:

stock OEM B16 header vs OEM B18(C4)... note their flanges are different too...

[james]

nice write up lads

[adeel]

i have a 4/2/1 2.5'' full system on my b18c4 and its a really good mod

freely rev's up better

[Dexter]

After further research i've been suggested an compromise: 4-2-1 mani with a 2,5" collector, a 2,5" cat and a 2,25" exhaust from the cat all the way to the back box. Reason was that as the exhaust air cools down a bit as it moves through the pipes, a 2,25" would be more optimal from the cat to back. This would suit me fine since Magnaflow has some really nice back boxes that only come with 2,25" inlets.

Comments or experiences with this kind of setup?

[johngreen537]

I'd personally go for 2.5" all the way mate

No sense restricting air flow in the exhaust if you've gone to the trouble of 2.5 collectors and cat....

[SteveMB6]

http://cgi.ebay.co.uk/TEGIWA-4-2-1-EXHA ... 2a0b3a3fee

this looks good!

[johngreen537]

It certainly does

Pricey though

[prezes]

If you're willing to stick with mildly moded b18c4 I would go for 2,25' . Have a look in my project and youu will find two dyno runs - 1st with standard exhaust and second with 2.5' throughout.

With 2.5 car feels smooth through the rev range but looses torque. So unless you're constantly driving on high rpm there's no point.

With standard exhaust:

With 2.5'