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Porting Rb 26 Cylinder Head

tacker

By tacker,
in Engines & Forced Induction

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tacker Mentor

tacker

Posted
Posted

Still i am having to build a forged bottom end for the car i though i may as well have a crack at porting the head to try and increase the flow.

Have to say with some tips from Steve at AAT here in the UAE has worked out ok and i am resonably happy with it so far dont think i need to go much more now.

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GTR1993 Mentor

GTR1993

Posted
Posted (edited)

Porting a cylinder head is good for any power level, but usually for lower power what is the point to goto the effort of pulling the head and porting it when cheaper mods can get good increases in power.

Have you got before and after flow figures? Exhaust ports are the most important on these things.

Edited by GTR1993
Rezlo Community Regular

Rezlo

Posted
Posted
Still i am having to build a forged bottom end for the car i though i may as well have a crack at porting the head to try and increase the flow.

Have to say with some tips from Steve at AAT here in the UAE has worked out ok and i am resonably happy with it so far dont think i need to go much more now.

Wow that head has either seen some nice broken piston, or serious contamination, I suggest you try pick out any parts you can before you have it skimmed, they form hot spots and detonate very easy if they come loose after skimming.

Also you need to match the ports, you can see all the visible intake ports are all different in shape at some point, what I find works well is P80 sanding roles to give a nice finnish and even tone and stop fuel walk on the walls, leaves you with a finnish like so http://www.rezlo.com/Pages/Cars/Misc%20pic...i%20(Small).JPG

Good luck, looking like a good start!

tacker Mentor

tacker

Posted
  • Author
Posted

yes the engine builder has explained about hot spots even the valve seat needed to be smoothed off to remove a lip that was just proud.

Pic is not the best and the marks look bad in the pics but not to bad in person.

The ports do need some more work and i think that they are the easy bit, i just had a crack at them today but i am waiting on more of the flap discs to arrive so i can do as you say.

All up about 12 hours on the rotory burr and i did remove a lot from the exhaust side so hope to get some benefit from this. And equal flow i hope, has to be closer than the factory effort casting marks all over the place.

Will post some more pics when i get the ports done.

Rezlo Community Regular

Rezlo

Posted
Posted

You should try those rolled up sanding roles, those give a very nice finnish, when I worked in the US they were very cheap, not sure about Ausi, but im sure they cant be to bad, once you got everything to shape just tear back about 20mm and use it to smooth all the material to the same finnish,

And yeah, pictures never do porting any good! :)

tacker Mentor

tacker

Posted
  • Author
Posted

HMMMMM nice work!! going to get back into it today and i know what its has to look like now:-)

I have really attacked the inner radius on the intake side and outer radius on the exhaust side but i still retained the standard valves.

will post some pic later today hopefully.

Swiper the Fox Grand Master

Swiper the Fox

Posted
Posted
INteresdting that you have removed the bottom half of the valve guides, i thought it was a common problem for rb's to crack the valve guides, and shorteneing them would only make it worse??

i would say the new guides have not been fitted when pics were taken.

Beer Baron Grand Master

Beer Baron

Posted
Posted
INteresdting that you have removed the bottom half of the valve guides, i thought it was a common problem for rb's to crack the valve guides, and shorteneing them would only make it worse??

yeah for sure. new guides fitted when head was finished. :P

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