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Rb26 Head Porting

rb26s13

By rb26s13,
in Engines & Forced Induction

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2BNVS Veteran

2BNVS

Posted
Posted

i probably wouldn bother unless ur going for some psycho amount of power, i run 400rwkw with my rb26/30 with still room to push more and it hasnt been ported. id probs only bother just doing a slight little tidy up, but dont go all out

Super Drager Mentor

Super Drager

Posted
Posted
i probably wouldn bother unless ur going for some psycho amount of power, i run 400rwkw with my rb26/30 with still room to push more and it hasnt been ported. id probs only bother just doing a slight little tidy up, but dont go all out

It says at the bottom 496hp@21psi ?? sorry to say mayt but thats not 400rwkw its actually around 370rwkw.i know im off-topic but im just saying.

Sydneykid Grand Master

Sydneykid

Posted
Posted

An alternative opinion, why not………..

RB heads (all of them) are NOT as good as some people would have believe, they have daggy castings, rough edges, unequal port dimensions, different sized combustion chambers etc etc.

Sure you can make lots of power without porting, but you have to run MORE boost to squeeze that airflow through the small ports.

MORE boost, that means MORE retarded ignition which means LESS response

MORE boost means SLOWER boost build, advancing the ignition will give FASTER boost build.

MORE boost means you need a bigger intercooler, to take that EXTRA heat (caused by the compressor working harder) out of the airflow produce by the compressor.

A SMALLER intercooler and pipework means FASTER throttle response

So after porting, you can make the SAME power at LOWER boost, with MORE response, FASTER boost build and QUICKER throttle response.

At the same time as he is porting it, a good machinist will equalise the combustion chamber volumes, so that the compression ratios on all 6 cylinders are exactly the same. Service the head, new valve stem seals, check the valves and guides, cut the valve seats, set the valve spring seat pressure etc etc. . All of which is essential for a reliable top end. Plus he will match port the inlet and exhaust manifolds, which on its own can make a huge difference

So why wouldn’t you port it? Cost, well it costs less than a mega intercooler and its pipework. Inconvenience, yep you have to give your cylinder head to someone for around a week, which is not that long in an engine build. Seems like a small price to pay considering the benefits.

:) cheers :D

Fitzpatrick Speed Works Mentor

Fitzpatrick Speed Works

Posted
Posted

On a side note I have some oversized valves for sale at the moment which would work very well with a head porting.

JHH seem very knowledgable to me, is there anyone in Sydney that can doa good job and turn around the work quickly and reliably???

Swiper the Fox Grand Master

Swiper the Fox

Posted
Posted
On a side note I have some oversized valves for sale at the moment which would work very well with a head porting.

JHH seem very knowledgable to me, is there anyone in Sydney that can doa good job and turn around the work quickly and reliably???

Just got our head heavily ported, oversized valves, and matched. Croydons sent it to someone who does all the port work on their "big" engines (GTR-700, RH9, JUN, DEVLSH etc). BUT..... it was sent there well before Xmas and only got it back a couple of weeks ago.

Faid Collaborator

Faid

Posted
Posted

My head was CNC ported, but i didnt pay for it. I had the head specialist at my job do it for me bribing him with beers and a BBQ. we have someone that studied at caltech for this sorta work, and at the workplace we have the cnc equipment and the dude that calculates evrything, so why not misuse that, its quite precision work with a buret and all that crapola measuring into the wee hours of the night. but its done perfectly and the results are great

2BNVS Veteran

2BNVS

Posted
Posted (edited)

interesting, i stand corrected then... from what a fair few ppl told me the cost/gain ratio wasnt worth it but ill look into it... so how much are we looking at here to get an rb26 head ported?

super dragger- as it says under my avatar that was previously using the rb25 head, stock rods, oil pump, and smaller fuel system, it has not been updated

ben...

Edited by 2BNVS
Sydneykid Grand Master

Sydneykid

Posted
Posted
interesting, i stand corrected then... from what a fair few ppl told me the cost/gain ratio wasnt worth it but ill look into it... so how much are we looking at here to get an rb26 head ported?

ben...

Quoting prices on cylinder head jobs is not always that simple. You don’t know what parts are needed until you disassemble the head and check everything. For example, RB’s often have bent exhaust valves. Not always all 12 are bent and they are ~$30 each, so do you include $360 in the quote or not?

There are 2 philosophies;

1. Charge ~$2K which is enough to cover ALL the possibilities, if that particular head doesn’t need some parts then you do OK on that one. The next head might need everything and you don’t do so well on that one.

2. Charge ~$1,300 plus parts, if required. That’s a normal head service which includes valve grind, new Nissan seals and gaskets (VRS kit), machine all surfaces (inlet, exhaust & head face), check the camshaft tunnels for straightness, bore if necessary, set valve spring tension and set the tappet clearances (including shims if required). Plus porting, inlet and exhaust ports and combustion chamber volume matching. If they are supplied, the inlet and exhaust manifolds are match ported to the head.

It doesn’t include valve guides (if required), valve seats (if required) inlet valves (if required) or exhaust valves (if required). If you want aftermarket (oversized) valves, cams, springs, followers etc then you have to supply them with the head to be serviced.

Our race team cylinder head guy is not too busy at the moment, so we can sneak in a head or two. He has done over 50 RB cylinder heads, I reckon he he can do them in his sleep. PM me for details.

:nyaanyaa: cheers :ninja:

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