Head Porting For Rb26

[Rbdirty30]

I'm currently get my rb26 head ported and my engine builder wanted me to buy an old head to cut up to see how big the ports are and where the water jackets are so he doesn't get close when porting it, now I thought they might be some good pictures for you to have a look at, I'm not sure weather it's been posted up before but here they are. Cheers

[Jordy32]

Very cool photos, thanks for sharing!

[Rbdirty30]

No worries! Can take more later if anyone wants to see more

[GTRPSI]

Get some of the divider in the exhaust port if you can please, there is a jacket that goes through the middle in there, you can see a tiny hole from the head gasket side going through the middle of it.

Also some pics of the sides of the ports to see the design on thickness of the water jacket areas on the sides.

Or in other words cuts made the other way......

Lucky you, i tried to find a cracked or damaged head locally to cut up but everyone wanted top $ for something only worth its weight in alloy.

[Daz]

You finished porting your head yet GTRPSI?

[GTRPSI]

Cyl 5 95% done on the exhaust side, others are roughed in, looking to buy a bigger house so house hunting ATM and the head work can wait till i find time and energy between that and running a business.

Took me 8-10 hours of touching and looking one exhaust port to bring it where i wanted it to, now will be replicating it across the other 5.

[Daz]

Bigger house definitely more important. I'm going to go see Barry this weekend, hopefully long motor all together ☺

[Rbdirty30]

No worries GTRPSI I'll see what I can do for the other way to cut it up I have a couple more of the head cut up so I'll get more and post them up, might be in a day or too tho when I get back out to the workshop

[GTRPSI]

Dont stress or rush as ive already worked out my shape on the head im using, however the information would be good for others and my other backup head i have for future work.

Thanks for taking the time to share the info, its these things that help everyone.

[Rbdirty30]

Not a problem

[Rbdirty30]

Well I'm about to cut them bits up you asked for gtrpsi as I'm about to start porting the head soon, I finished my porting on the bit that's attached to the head a while ago, took about 10 hours to complete, a question for people who are experienced in head porting what kind of finish do you use? I'm using 80 grit on a little die grinder flapper disc, here's a few pics of how it looks,

Port matching to my hypertune runners

T

The left is standard the right is my job

[HarrisRacing]

You'd be the coolest buy ever if you could get some fine graph paper and trace/etch out the shape to some sort of scale. You know, the indiana jones trick with the charcoal on top of the paper on top of the head. It would give everyone solid dimensions of the ports and resultant thickness.

Also the full half-cut of the eshaust port would be great as well.

[GTRPSI]

Ill get some pics and better still measurements of my Drag head tonight or tomorrow to share, ive only completed the exhaust ports to satisfaction, inlets are partially roughed out, still studying them and not enough hours in the day.

Measurements might be better at certain points in the ports so you can see how far it can be taken...remember the exhaust ports are the major restriction, inlets dont need that much work.

My exhaust port shape was based on carefully measuring 2 heads i was granted access to, one was made for a 1200Hp RB build by a local porter, the other was a Sydney port job for a all out drag engine that was also at the workshop.

Ive got their inlet specs, however im yet to overlay what they did and study them properly.

Dont ask me how many hours went into the exhaust ports.......

And dont forget, outright drag specs wont work well on the street as flow velocity will be low, however its a indication of how much room there is to work with safely.

Edit; to answer your port finish question, leave the intakes rough, 80 to 120 grit to help atomize the fuel, exhausts can be the same for the street, ive gone for polished exhaust ports, not needed on a street engine though as they will be carbon coated quickly.

Edited July 29, 2015 by GTRPSI