I have a B16 with CTR cams, Port and Polished head with bolt ons, stock bottom end and compression. Now my exhuast is 2 1/4 inches crushed bent. I was wonderin if going 2 1/2 inches would make that big of a difference and help out top end?

And also, I have a DC sports 4-2-1 one piece. A lot of people are saying this is a crappy header. What would be a good header for me? I hear a lot of good things about the ITR JDM 4-1 since it has a 2 1/2 inch collector. I know that ANR and all those other 800+$ headers are well worth the money but I was looking to spend about 300-500 on one. Any other headers out there that are pretty decent?

Thanks for the info guys

Matt

 

2.5" would probley be a little better, you wouldnt notice a huge difference, but you should definitally be flowing enough air to have sufficient backpressure for 2.5" pipes.

and for racing applications you should really make sure you get a 4-1 header, it will give you more torque.

 

backpressure has no effect on anything but a loss of power...no reason it should have been mentioned in this thread


a JDM DC 4-1 and 2.5" mandrel is a good street setup, and i just happen to offer a REALLY good price on the JDM's...just pm me

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSRswapandslow. &raquo;</TD></TR><TR><TD CLASS="quote">backpressure has no effect on anything but a loss of power...no reason it should have been mentioned in this thread


a JDM DC 4-1 and 2.5" mandrel is a good street setup, and i just happen to offer a REALLY good price on the JDM's...just pm me</TD></TR></TABLE>what do you mean it shouldnt have been mentioned? its has everything to do with it. A basic b16a doesnt need 2.5" pipes, if he was worried that 2.5" could be too big and he could not have enough backpressure. I was simply letting him know that with the work he has done to the engine, 2.5" would be fine.

 

Back pressure is a myth. Its all a question of exhaust velocity and the rate at which the exhaust gases cool. The faster the exhaust gases cool, the slower they exit. This slowing down affects the rate at which the exhaust gases exit and the path they take (exhaust velocity), and thus for lack of a better word, back-logs everything. As you increase the size of the piping you increase the rate at which the gases cool. Bigger piping is waranted if your motor has increased the rate at which these gases exit. 2.5" should be perfect for your setup.

 

^a very good post

 

Why does the backpressure issue come up in every single exhaust post?

 

because since the late 50's when it was first brought up.....it's been a VERY common myth. A lot of ppl still believe in it, and they pass that belief onto others.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SiRGodfather &raquo;</TD></TR><TR><TD CLASS="quote">Back pressure is a myth. Its all a question of exhaust velocity and the rate at which the exhaust gases cool. The faster the exhaust gases cool, the slower they exit. This slowing down affects the rate at which the exhaust gases exit and the path they take (exhaust velocity), and thus for lack of a better word, back-logs everything. As you increase the size of the piping you increase the rate at which the gases cool. Bigger piping is waranted if your motor has increased the rate at which these gases exit. 2.5" should be perfect for your setup. </TD></TR></TABLE>So..... 2.5 isnt necssary is it?

 

it isn't necessary...but it's better

 

So would it be "worth" it to get a 2 1/2 inch exhuast or should I not even worry about it?

Also, anyone have any input on my header thoughts?

Matt

 

i mean, it's up to you

we aren't talking huge gains here...but in an n/a honda, especially a b16 (shiver), any gains are good gains and it just matters if those gains are worht it to YOU

 

I was also plannin on a pair of Skunk stage ones, so the bigger and better exhaust would do nothing but help out.

GSRswapandslow, you never gave me a price for the header?

 

$260 shipped

 

I take it thats ceramic?

 

yeah

 

I have a 2.5 inch T1-R exhaust on my b16.
When I dropped the exhaust and ran open header, I picked up 13whp.
Makes me think I should have got a 3inch.

 

There is also a little thing called exhaust velocity which directly correlates with exhaust scavenging effect. The pulses of exhaust gas that come out of the primaries in the header helps pull the next pulse down the exhaust piping. On a four cylinder like ours, three inch's would be too big because the pulse of gases would simply deteriorate inside the tube. There is a plethora of information on exhaust efficiency and flow on this site...Search.

2 1/4 is fine for a street set. 2 1/2 is better for high power motors, and three inch exhaust on a four cylinder NA motor is just stupid unless its a Drag motor making 300 na hp.

And for the guy who said that 4-1 manifolds yield more torque...No, they don't.

 

1. 4-1 manifolds, don't always yield more torque

2. a good 4-2-1 header would be comptech (in your price range) Only stepped header mass produced. Great quality and the guys at comptech are nice ppl. If you are interested in comptech products please PM irev210 he sells them brand new in da box.

3. As exhaust pulses travel down the tube and arrive at the collector they send a negative pressure wave back. This pressure wave is then what aids in good scavenging. The controlled merge of the collector will reduce the severity of the pressure wave. Too severe can over scavenge the cylinder.

4. i think 2 1/2" would be too big. Your engine combination doesn't seem to be making the necessary power. Or have the displacement to need 2 1/2" worth of piping.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eLusive ek4 &raquo;</TD></TR><TR><TD CLASS="quote">

4. i think 2 1/2" would be too big. Your engine combination doesn't seem to be making the necessary power. Or have the displacement to need 2 1/2" worth of piping.</TD></TR></TABLE>

I have seen WITH MY OWN EYES a 2.5" exhaust make power over 2.25" on an INTERNALLY STOCK B16A without losing power anywhere in the curve. From 4000rpm and up it gained. There ended up being about a 3-4 whp difference peak.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WAFFLES &raquo;</TD></TR><TR><TD CLASS="quote">

I have seen WITH MY OWN EYES a 2.5" exhaust make power over 2.25" on an INTERNALLY STOCK B16A without losing power anywhere in the curve. From 4000rpm and up it gained. There ended up being about a 3-4 whp difference peak.</TD></TR></TABLE>

As have i, usually that gain in horsepower is making up for a header that isnt designed to that specific application

Example: too long a header, too big a header, too short of a header, not long enough of a header.

 

usdm dc 4-1 for the b16a engine was used.

 

The usdm dc 4-1 header is designed to fit a wide rnage of applications it is designed to be optimized for one particular application. Your also delaing with a CARB header

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eLusive ek4 &raquo;</TD></TR><TR><TD CLASS="quote">The usdm dc 4-1 header is designed to fit a wide rnage of applications it is designed to be optimized for one particular application. Your also delaing with a CARB header</TD></TR></TABLE>

not quite sure what you are saying here.

CARB header....yes
As far as I know, a 4-1 designed to fit on the B16 will not fit on the b18C engines because it will not clear the oil pan. I have seen one rub the oil pan on a lsvtec motor.( I wasn't quite sure if you were saying it should fit on all b series designs or what...please reiterate you point).

 

Hmm. I dont know what to do. Some are saying it makes power and some arnt. Im puttin down 161whp with my CTRs and I was thinking of upgrading to some Skunk stages ones or some kind of stage one. Thought maybe the 2 1/2 would help me breath a lil better. Im also going to do a bigger TB and thinking on a intake manifold. My buddy has a B16 rex with a cheap intake and a Thermal R&D exhuast, its 2 1/2 and it pulls hard.

Best thing is prolly buy a 2 1/2 and dyno.

Thnaks for all the info though guys! Even though Im still confused

Matt