Promote more airflow through the head

**beeza** · 05-01-2016 10:33 AM

Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!

Aim:*To have more airflow through the head because horsepower is restricted by how much air you can move through the head PERIOD.

Required:*Round file,texta.

Steps: This mod was done on my d16y4 and it works,so I cannot answer if it will work on b series or if u would want to do it to the b,i would but that's just me,I like to live on the edge.Those who own a d need every little bit of horse power we can get CHEAPLY.

Background:

Ok I Have Done all the bolt on mods including 60mm tb,port matched the stock im.

To do this i had the stock tb bored out from 56mm to 60mm at the local machine work shop for $40 then got a 60mm butterfly plate from a b20 honda crv at the wreckers.Then calibrated the tps.

To port match the im to the tb,the im will need to be removed.The link at the bottom of this post shows you the tool u can buy to put in your drill to achieve this. U can also use this tool on the exhaust ports as a fair bit of material needs removing.

Next on your im,use your round file to open the 4 runners/ports from the stock 40mm to 42mm by taking off 1mm all the way round.Keep with the natural flow/lines of the runners and U will find what material needs removing. It is more the sides than the top and bottom.When measured equals 42mm high and 42mm wide.

The next step is done with the im removed and the engine/head still in the car.

NOW,

The Head, intake side: The 4 ports measured 40mm by 40mm. So u want to open them up with the round file to 42mm by 42mm again keeping with the natural flow of things.U can use the texta to run a 1mm line around the ports as a guide.Also stuff a bit of a rag into the ports so no metal shavings get in there.

The Head,Exhaust side: Height is 30mm,Width is 38mm.AGAIN,keeping with the natural flow of things I removed material.The result was 30mm by 43/44mm.Then port match the headers . Remember the rag in the ports!

Make sure you port match your intake and exhaust gaskets too.

Other comments:

This mod works cause I've done it.

Do it at your own risk and enjoy doing it.

Sorry there's no pretty pics this time.If anything is hard to understand,ask.

https://www.google.com.au/search?q=d...aIoBAHTNpIM%3A

In summary, height (H) and width (W)

IM before - H = 40mm W = 40mm
after - H = 42mm W = 42MM

INTAKE on head before - H = 40mm W = 40mm
after - H = 42mm W = 42MM

EXHAUST on head before - H = 30mm W = 38mm
after - H = 30mm W = 43/44mm

So this isnt porting the head as such we are just doing what is stated above to promote more airflow through the head.

I have to admit I finished the exhaust side a few months ago and was concerned about the intake side on the head thinking I may _uck it up but in the end it felt right so I did it and it worked

**bennjamin** · 05-01-2016 12:08 PM

So this is a DIY porting of the throttle body to properly match intake manifold side right ?

Just a WARNING - you MUST do this with the intake manifold OFF the engine. This is to prevent fine metal dust and swarf ending up ingested to your engine and other areas....a possible fatal scenario for your rings and block. Stay safe kids !

**connorling** · 05-01-2016 12:41 PM

Originally Posted by bennjamin

So this is a DIY porting of the throttle body to properly match intake manifold side right ?

Just a WARNING - you MUST to do this with the intake manifold OFF the engine. This is to prevent fine metal dust and swarf ending up ingested to your engine and other areas....a possible fatal scenario for your rings and block. Stay safe kids !

yes.
that!

**beeza** · 05-01-2016 05:40 PM

I edited the post. Hopefully things are clearer.let me know.

Brett.

**u mad?** · 05-01-2016 07:15 PM

Beeza am i reading this right, your filling down the ports on your CYLINDER HEAD with a file, while the head is still on the bottom end?

**RenzokukenJ** · 05-01-2016 08:10 PM

I got shavings in my cylinder 4, what can I do

**beeza** · 05-01-2016 08:14 PM

U of all people!

U know me m8,I do what feels right.

And it worked.

Car runs a treat.pulls harder and at 160km/hr (track) its hard to hear the exhaust,just purring.

Im not 'filing down' just opening up with the natural flow of the ports/runners.