Diy Head Port And Polish

[waxracing]

Cartridge rolls

[marksuxass]

Cartridge rolls

Thank you very much. What grade would you finish it in?

[marksuxass]

Just finished the porting, who wants pics?

[wolverine]

Stick em up.

[marksuxass]

Head still hasnt been serviced. Will flow bench the head and post results

EXHAUST:

-Bumps removed

-Casting marks and bowl areas cleaner and smoothed

-Mirror polished

INLET:

-Cleaned cast marks and bowl areas

-Knife edged the splitter

-Matched the balance tube to inlet ports

-Finished in 80grit

Also polished the combustion chambers, Might chamfer the edge of the quench pad whe n it comes back from a facing.

[Beer Baron]

looks good mate. nice effort. hope it performs well.

[T04GTR]

nice work. dont be shy on the short side radius. you really need to remove some of the valve seat to get a nice transition. if you want better fuel economy you can cut the inlet port divider down further to lower the "wetted" area in the port.

[marksuxass]

nice work. dont be shy on the short side radius. you really need to remove some of the valve seat to get a nice transition. if you want better fuel economy you can cut the inlet port divider down further to lower the "wetted" area in the port.

Thanks for that, what do you mean by the short side radius? How far should i lower the divider, about 10mm?

[Nee-san]

whack it on a flow bench !

Nice work mate, do you do fabrication stuff for a living ?

[marksuxass]

whack it on a flow bench !

Nice work mate, do you do fabrication stuff for a living ?

Nope im a nissan tech. This is also the first time ive ever used a die grinder

ALOT easier then i first expected

[T04GTR]

10mm is quite abit. have a look at some of the newer nissan engines. the vq35hr vs the vq35de is a good compaison. the de has the usual divided ports where as the hr has almost no divider at all. its not a flow advantage but more of an eficientcy thing

[marksuxass]

Ok thanks for that, what do you mean by the short side radius?

[blue_vl_t]

the short side radius, or know as the short turn, is the small radius at the bottom of the port where the port "turns" around 90 degrese to meet the valve saet.

this is usually quite ulgy in shape, between where the valve seat is fitted to the head, and the machining to fit from factory. I normaly just "round" the area slightly and make it a smooth contour. Unless you know what your doing exactly i wouldnt go removint too much material from the area.

The head is looking good though, it does look as if the valves could be deshrouded a bit more in the chamber, but just being picky

[t_revz]

did this ever get flow tested or dyno results once the engine was re-assembled?

[Dasmbo]

Have started the port, cleaned up the combustion chambers and got rid of 1 exhasut bump (3 flap wheels later). Would like more of a mirror finish on these items, What should i use?

Hi i used a few old holden tappet push rods cut a slot down them at one end so i could fold abrasive paper in and connet it to my drill which has a flexi drive and used different grades of paper untill i got a mirror finish same as flapper disk i started of with belt sander paper and cut the push rods to different lengths so i could get different angles. I match ported the manifold to suit the head ports i also mirror polished my runners on my inlet manifold but left the ports in the head stock, Also polished up the exhaust at the head ports and turbo end.

I tried the flapper disks but soon gave them up good luck.......

[Driftnuttz]

I know this is old, but heres my take.

I have been working on a rb20det head. From what I have been told, unless you know 100% what your doing DONT MESS WITH THE SHORT SIDE. You can really mess up the port and lose a ton of power by over porting or miss shaping that. Air goes in a straight line, and really does not like to turn. With that, you can see good gains by removing stuff around the seat, NOT much but some. Also DONT OPEN THE PORT ANY unless your looking for big big top end power. The first little bit of the port is what gives the speed, the rest tells how much air can flow at that speed. Now if you port one part you have to open the rest. If your port flows 200cfm at the port open, 150cfm in the middle, 125cfm athe the throught, and 100cfm at the valve seat. Now you ported the opening a little and made it flow 230cfm, you still will only see 150cfm, 125cfm, and 100cfm at the valve seats. If your going to port any where on your head, at least clean up the whole port. Be carefull not to take out too much stuff, and be carefull around the short side turn.

What I did to my head was shrink the splitter in the intake port, opened the throught (I didnt mess with the short side much at all) a little, and got a 3 angle valve job. This should improve flow throught the whole port and not slow the air down. Now time for the before and after pics....

Before

After. I didnt mess with the outside walls only the inside splitter.

This is my ex port where I removed the stud hump

Edited October 19, 2011 by Driftnuttz

[marksuxass]

Heads still on my work bench and yet to be bench flowed. Have been in contact with Headorque here in Perth, and they said its not 100% critical to flow bench it as its a forced induction engine, with only minor porting done. Probly still do it anyways when I send it to get faced.

[sweefu]

I don't understand the appeal of a mirror finish. All the best jobs I've seen on well built engines have been finished with 120grit on a flapper wheel. Mirror finished can be bad, you are prone to a sticky fuel / air / gunk residue on the inside walls of your intake chamber etc if there is a mirror finish. You need a light abrasion given by a flapper wheel with a grade that isn't too fine in my opinion (Newbie / Novice at best) though I have seen some expensive engine builds, along with backyard builds and most in-between.

[zebra]

I don't understand the appeal of a mirror finish. All the best jobs I've seen on well built engines have been finished with 120grit on a flapper wheel. Mirror finished can be bad, you are prone to a sticky fuel / air / gunk residue on the inside walls of your intake chamber etc if there is a mirror finish.

Think of a golf ball if you don't believe him

[T-Rex]

My brother is a bit of a genius with hand porting, he has ported dozens of heads, one set was for a 3000hp TFX Hemi drag engine. I asked him to port my WRX heads when I was building an engine so I will put up a before and after pic of the inlet port. From what he told me, most of the Jap cylinder heads are good from the factory and only need a little clean up, unlike the older V8 engines, etc. If you increase the port size too much all you will do is create a flat spot in the low rpm range, and get bugger all improvement up top.

Before

After