ok im going boost on my d16y8 sohc and i know i can get sum extra power out of that vtec head. But ive heard that some time port and polishing and head isnt the best thing cuz yea your getting more air into your combustion chamber, but on the other hand i heard that just polishing your head is good enough and you get better numbers because a smaller port= more air velocity on boost, sumthing called a venturi effect or sumthing like that. and i was told that air going faster through your ports its better than having alot of air just going through not as fast. so guys help me out on this theory. thanx

 

Big ports are lazy ports.
Alot of time the porting just consists of blending the bowl area and cleaning up casting marks.
Dont polish the intake side finish it up with some 80 grit.

polish the **** out of the exhaust side.

 

deshrouding valves/combustion chamber design is where you get most of your power on a honda head. but on boosted setups, hogging out the exhaust side helps out also

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B6tPoweredMx3 &raquo;</TD></TR><TR><TD CLASS="quote">Big ports are lazy ports.</TD></TR></TABLE>

There is more to porting than just getting a grinder and hogging out the ports. Read up on valve shroud, valve seats, etc and get a good idea as to what is involved before you do something you might regret.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">

There is more to porting than just getting a grinder and hogging out the ports. Read up on valve shroud, valve seats, etc and get a good idea as to what is involved before you do something you might regret.</TD></TR></TABLE>

Don't take my statement the wrong way, by hogging out i didn't mean just going at it with a dremel haha. Just that you will see better gains by taking material out of the exhaust side, and maintaining the velocity on the intake side. This is because of the trimedous amount of backpressure in the exhaust side

 

Ha, I was actually typing my post the same time you were, so that wasn't directed at you at all. Funny we both used the same word though.

You are correct about the intake side, although on the exhaust side I wouldn't necessarily hog out the whole port, as it's probably large enough. As usual, concentrate on the area around the valve, it's usually the biggest restriction.

There's also interesting things you can do with valve size and combustion chamber design to minimize blow-through under valve overlap, but that's another story...

 

so if i port and and polish both the intake and exhaust side it wont be any good

 

on the intake side you don't want to polish it at all except within the bowl right under the valve seat to blend the port to the seat. the intake port should be rough. this is to create a very small amount of turbulance to keep fuel in suspence. by polishing the intake walls will create the boundry layer effect makes air "lazy" on the walls losing velocity. when fuel is in this area it tends to stick to the walls and entering the cylinder less atomized. remember that the largest gain in airflow are in all done in the bowl and a good multi angle valve job. also port match your intake mani and head to the gasket so there is no sharp edges to flowaround. don't gasket match the bottom of the intake port though.

 

if you want to check out some pics of ported heads paying close attention under the seat. finess blending only. most of the heads you see all done up are race heads and show peices. for the street, keep it simple.

 

I just did one of these heads for Full Race and there is alot to be had by porting the intake and exhaust ports..I think the head is WAY more tricky to grind then any other Honda head I have encountered thus far..ALOT of work to be done, this is definitly no B series head!

 

so is every one here implying that every other person that waste their money on porting and polishing the hell out of there heads are not getting the expecting horsepower numbers that they are paying for? cuz im just trying to go for the best bang for the buck

 

We cannot say anything about what you will do to your head. We don't know you, or your level of knowledge with regard to porting heads. We cannot answer the question "how much more power will I get if I port and polish my head" because you cannot perform a flow bench test over the internet, and we don't know what else you have done to the motor.

Generalizations:

More air in the motor = more power out of the motor.
Under some circumstances, quality of air &gt; quantity of air. Mixture motion is important.
Not all port jobs are created equal. There is are many right ways, and many wrong ways.
Don't worry about polishing anything unless you're chasing the last 2hp. The shape is more important than the surface finish.

 

from my knowledge you get the most power from porting the intake side, you also want to make sure that you port match just like they mention above, turbulance is a great factor in your head, but i personaly wouldnt port out the head, because you really dont know how much cfm's are flowing through each port, and you want to keep the cfm's in each port as close as you can to the rest, i think your better off with a larger throttle and porting out the intake throttle hole, so you can match the ports.

 

basically i wanna know how ppl out there get the most power out of there head..i know a cam does the job..but i mean more of when it come to porting and stuff like that...sum ppl say certain things and abide by principals they have knowledge of and get power and other ppl just go with the theory of the more and the more power...so basically i wanna know exactly what i have to do to get the most out of my head...im not no professional ASE certified tech but i have pretty much alot of knowlege about every single automobile part...its just that i hear things here and there and im not perfect so im really interested in knowing how can i acomplish a good head job...im pretty sure sumone out there has numbers on almost ever single thing they have done with a honda head...come on what hasnt been tried on a honda..especially a vtec head...

 

send it to dart or portflow because you personally are not going to squeeze every bit out of that head, even if you had a flow bench. It takes years of r&d and trial and error to learn what heads like

 

but damn there has to be sumone out here that knows the difference in horsepower gains wheater you port and polish the head or use basic principles...i know 90% of ppl always go for the port and polish...

 

What exactly do you want us to tell you? We've been giving you suggestions, but we can't tell you if the port job you do will be better or worse than someone who does them every day. And The Big Boys aren't going to come on here and go "well this is what I do for the best port job there is".