I have a built b20vtec motor that I'm working on squeezing the last bit of power out of it. My build consists of:

sleeved bored to 85.5
JE high comp pistons about 12.5:1
Titanium supertech internals
toda spec C cams
5 angle CNC port and polish
Blox intake manifold
70 mm throttle body
Knock off 4-2-1 header and two runners are flattened due to clearance

Last time I dynoed it I got 210 whp on a mustang dyno and I cant remember the torque number but it was around 160. I'll try and dig up the graph. Now my question is I'm stuck on the fence between SMSP B19 and the B20vtec header. I'm not too worried about clearance as this will no longer be a street car and mainly for the track. Which header would you guys suggest?

 

Why don't you ask Dave? He is on this board:
https://honda-tech.com/zero...=4028

 

I actually spoke with Dave and he said unless I'm pushing 250 whp that he would go with the B19 and for the better ground clearance. Because of that I'm leaning towards the B19 but I dont want to put all that money towards that and then later on find out that I could have gotten more out of the b20vtec. From what I have been told a mustang dyno reads about 10-15% lower than a dynojet. So I believe with my current setup and good header I could push around 250 whp on a dynojet. I looked through the b20vtec build thread to see if I could find someone with a smilar build running a SMSP header, but no luck.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by integratuner77 &raquo;</TD></TR><TR><TD CLASS="quote">I actually spoke with Dave and he said unless I'm pushing 250 whp that he would go with the B19 and for the better ground clearance. Because of that I'm leaning towards the B19 but I dont want to put all that money towards that and then later on find out that I could have gotten more out of the b20vtec. From what I have been told a mustang dyno reads about 10-15% lower than a dynojet. So I believe with my current setup and good header I could push around 250 whp on a dynojet. I looked through the b20vtec build thread to see if I could find someone with a smilar build running a SMSP header, but no luck.</TD></TR></TABLE>

250 whp on a dyno jet?? is that on pump gas or race gas?? no way you're gonna come close to my dyno numbers through an exhaust LOL!!!! AAAAAAAAHAHAHAHAHA!!!!
i'm not even gonna post my dyno sheet...it's all over this forum already

there are a lot of choices for a header out there...when i dynoed my setup, i was on an RMF race header...on the streets i'm running the SMSP. i haven't dynoed through the SMSP though...debating on either a complete rebuild or just a tune up...pending funds.

 

I plan on running race gas on my next tune. I have been running 93. I realize that I'm not going to pull out 20 whp with just a header, but I want to get the optimum header for my setup. I'm not sure the difference between the primary sizing but I know there is a 0.5" difference in the collector sizing between the b20vtec and the b19. I dont want to drop close to a grand for the b19 and find out later down the road that I'm restricted by it and should have actually gone with the b20vtec header. I realize they are both high quality headers I'm just trying to get the right one for my setup.

I've searched around and cant find any good technical articles on exhaust header sizing. I can find all kinds of things on 4-2-1 and 4-1 differences and different configurations. I would like some theory behind primary sizing and collector sizing and matching it to the engine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by acydphryck &raquo;</TD></TR><TR><TD CLASS="quote">250 whp on a dyno jet?? is that on pump gas or race gas?? no way you're gonna come close to my dyno numbers through an exhaust LOL!!!! </TD></TR></TABLE>

Why not? I have a customer with a smaller motor making a corrected 243 blowing through a CAT and exhaust. I'm not understanding why you post in here really...

 

My old 86.5x89 13.5:1 replaced with a 85.5x89 12.6:1
I run a custom B19 and I am very happy with it's performance and ground clearance...

 

If you are willing to spend the money for the best possible then go with a custom design. The 4-1s are hard to be in a race application.

PM me if you want more details or need my help.

 

Unfortunately I can't PM yet since I just signed up here a few days ago. I have been pretty active on other forums but never here. Anyways what do you mean by

"The 4-1s are hard to be in a race application."

I'm shooting to be competitive eventually in pure street and plan on making this a drag only car eventually. It has been slowly evolving. At this point I want to make it the best it can be and I dont want to cheap out or choose the wrong parts. I would rather do it right the first time around. This is why I'm undecided between the b20vtec and the b19 header. I have heard excellent things about them both but I want the one that will best suit my setup. I have been unable to find a good technical read on selecting exhaust primary sizing and collector sizing. All I can find is general rules of thumb. Thanks for all the advice so far.

 

Nobody knows Dave's manifolds better than Dave, bottom line. I would do what he reccommends.

 

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

250 whp on a dyno jet?? is that on pump gas or race gas?? no way you're gonna come close to my dyno numbers through an exhaust LOL!!!! AAAAAAAAHAHAHAHAHA!!!!
i'm not even gonna post my dyno sheet...it's all over this forum already

there are a lot of choices for a header out there...when i dynoed my setup, i was on an RMF race header...on the streets i'm running the SMSP. i haven't dynoed through the SMSP though...debating on either a complete rebuild or just a tune up...pending funds.</TD></TR></TABLE>
I made 242 and 170tq with a small tube rage header with two flattened runners and crush bent piping on california 91 **** water. Thats more than yours

 

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

Why not? I have a customer with a smaller motor making a corrected 243 blowing through a CAT and exhaust. I'm not understanding why you post in here really...

</TD></TR></TABLE>

love you too willis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by soulpwr &raquo;</TD></TR><TR><TD CLASS="quote">
I made 242 and 170tq with a small tube rage header with two flattened runners and crush bent piping on california 91 **** water. Thats more than yours </TD></TR></TABLE>

like b19coupe says...

"word to your mother"

 

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

like b19coupe says...

"word to your mother" </TD></TR></TABLE>

or like Drob says....happy dyno