im getting my b18b1 head ported out and was wonering if i should go with larger valves cause i want some low end tq and have heard that they take that power power away im going turbos BTW =]

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xapathyx &raquo;</TD></TR><TR><TD CLASS="quote">im getting my b18b1 head ported out and was wonering if i should go with larger valves cause i want some low end tq and have heard that they take that power power away im going turbos BTW =]</TD></TR></TABLE>

I know someone's going to be a hero and say this is in the wrong section, but lets see if anyone with a 06+ Si actually has some knowledge when it comes to engines. I'd help you, but I don't know very much when it comes to engines. Good luck with your build. Cookie to the first guy to help him.

 

^ haha...well it is in wrong.

from my understanding upgraded vales will only help with top-end power and help reduce friction. i dont know the size of the stock b18 intake and exhaust ports as that can play into it as well. it also depends on the the degree of porting you do.

porting heads and adding boost actually will decrease boost.

 

this is true but when u have a turbo that pumps more volume (CFM) u can still achieve the same boost levels, im just looking for a good amount of low and mid TQ

PS. my bad if i posted in wrong thread

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pd0019 &raquo;</TD></TR><TR><TD CLASS="quote">
porting heads and adding boost actually will decrease boost.</TD></TR></TABLE>

never heard that. sounds ridiculous too.


Modified by dirtySOHC's at 3:35 AM 5/22/2008


Modified by dirtySOHC's at 3:36 AM 5/22/2008

 

pretty simple actually.

turbos work basically in the principle of air velocity.. make the ports too big and you loose the velocity..

even simpler than that.

Try blowing through a small straw, see how much back pressure you get in your mouth.Now try blowing through a garden hose, see how little back pressure you get in your mouth.But notice how much more air you blew through the garden hose.

 

slightly larger ports will give u more power just dont go too big or else you're gonna lose power. its the same principle with exhausts.

 

if your porting the head you are not going to notice any gain unless you use bigger valves. so absolutely go with the bigger valves if your porting

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by draken187 &raquo;</TD></TR><TR><TD CLASS="quote">pretty simple actually.

turbos work basically in the principle of air velocity.. make the ports too big and you loose the velocity..

even simpler than that.

Try blowing through a small straw, see how much back pressure you get in your mouth.Now try blowing through a garden hose, see how little back pressure you get in your mouth.But notice how much more air you blew through the garden hose.</TD></TR></TABLE>

but if your wastegate spring or boost controller is set for a certain amount of boost then thats what the turbo will build up to before the wastegate opens. 10 psi is 10 psi whether you have a ported head or not.....if that's what your wastegate is set to open at.

have you owned a turbo'ed vehicle before?

 

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


have you owned a turbo'ed vehicle before?</TD></TR></TABLE>

i have not personally owned a turbo vehicle. i do however own a supercharged mini cooper s. wich im trading in for a new one with a turbo so started doing alot of research. and my roommate is pushing about 390 hp out of his turbo gti that i basically did half the work on

 

This thread is terrible.

It's in the wrong section.

It's full of misinformation.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93civicjaydm &raquo;</TD></TR><TR><TD CLASS="quote">if your porting the head you are not going to notice any gain unless you use bigger valves. so absolutely go with the bigger valves if your porting</TD></TR></TABLE>

not true with a b-series head (or any head really)

draken187,go buy this book. you need to keep researching turbos.

 

The nblwoing through a straw thing and garden hose is a bad analogy. that analogy is used to describe the backpressure on an exhaust. The pipeing to big no back pressure.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by draken187 &raquo;</TD></TR><TR><TD CLASS="quote">

i have not personally owned a turbo vehicle. i do however own a supercharged mini cooper s. wich im trading in for a new one with a turbo so started doing alot of research. and my roommate is pushing about 390 hp out of his turbo gti that i basically did half the work on</TD></TR></TABLE>

so then why did you try to give an explaination of straws and garden hoses to illustrate the difference b/w a ported head and a non ported head.

there is no difference as far as boost levels are concenred.

 

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


draken187,go buy this book. you need to keep researching turbos.

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

great book

 

thanks for the book.. problably gonna order it today or tomorrow.

as far as the analogy.. i guess it made sense in my head...

if you blow air through a smaller hole you get less air but at much higher pressure.. blow air out of a bigger hole and you get more air but much less pressure.. you port a head u make the hole bigger.. but as i stated before i am just starting to do research on this subject just like the op

 

If you really want to know about 4 stroke motors, buy this book:


http://www.amazon.com/exec/obi...42369




Modified by IT GUY at 4:33 PM 5/22/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by draken187 &raquo;</TD></TR><TR><TD CLASS="quote">thanks for the book.. problably gonna order it today or tomorrow.

as far as the analogy.. i guess it made sense in my head...

if you blow air through a smaller hole you get less air but at much higher pressure.. blow air out of a bigger hole and you get more air but much less pressure.. you port a head u make the hole bigger.. but as i stated before i am just starting to do research on this subject just like the op</TD></TR></TABLE>

and like i said the turbo will continue to build boost until the wastegate reads the set amount of boost. no matter if you're blowing through a "straw" or a "hose"

 

my thing about loosing boost was referring to supercharge setups, my bad.

turbo is different. i think with turbo, if you port you spool up faster but still keep the same boost level.

 

lol dont really need that book. i did go to school as a mechanic for 4 years and worked for about 3... just never got into it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by draken187 &raquo;</TD></TR><TR><TD CLASS="quote">lol dont really need that book. i did go to school as a mechanic for 4 years and worked for about 3... just never got into it</TD></TR></TABLE>

with your boost logic....sounds like you do

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by draken187 &raquo;</TD></TR><TR><TD CLASS="quote">lol dont really need that book. i did go to school as a mechanic for 4 years and worked for about 3... just never got into it</TD></TR></TABLE>

which book? you already said you were ordering 'maximum boost'

were you talking about professor blair's book? I don't know anyone who couldn't learn something from that book.

what school for mechanics takes 4 years btw?

 

professor blairs is what i was talkin about, if u think its that informative il look into it tho.. as far as school i went to technical highschool and after that worked for subaru for 3 years.. then just wasnt into fixing cars

 

The deal with porting, don't do it yourself and the person that is doing it needs to know what thier doing. A random port job can and probably will make you lose power because of the loss of air velocity. I wouldn't trust anything that is not a proven CNC program.

Also, why keep the LS head?
What are your power goals?

If I were you I'd just get a vtec head and call it a day. 450 whp is not a problem on a stock b16 head/cams/intake manifold/throttle body with some boost.

If you really want to keep the ls head get some springs/retainers/ and big cams, and get a new intake manifold (ls ones suck) if your power goals are high enough. If its not above 300 whp I'd leave it all stock.

And who cares if your "losing" boost? psi means nothing to me, just a number. WHP is the only thing i care about

 

the only thing i can think of PSI wise on a s/c car that effects it is the aftercooler or intercooler. the intercooler gives you colder air producing a loose in boost but colder air means more WHP. a aftercooler i know what it is but...well not really sure what it does anyone wanna give me some knowledge on a aftercooler.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kuja396 &raquo;</TD></TR><TR><TD CLASS="quote">The deal with porting, don't do it yourself and the person that is doing it needs to know what thier doing. A random port job can and probably will make you lose power because of the loss of air velocity. I wouldn't trust anything that is not a proven CNC program.
</TD></TR></TABLE>

I'd trust the guy who works for Skunk2. He definitely knows what he is doing. I don't remember his name, so sorry for generalizing; I know he's asian.

But you are absolutely correct. You can't just grab a die grinder, and dive into it.