Just wondering if there is enough meat for
squaring and opening up a common round port?
This would equal the volume of an oval port if
it can be done and would be much cheaper for
boost applications.

Attach file:

---

  square porting of roundport a12.jpg (7.95 KB)

Somebody donate an old head to D. He can use a hacksaw and cut it in half to see how much meat is available for porting.

someone donate me hacksaw blades also :)

The angle grinder will be the scientific cutting tool.

Is the objective to have the preferable cubustion chamber configuration, but with the greater flow potential of the oval port heads? Or is there some other reason for this?
If so, Are GX heads really so hard to find?

The racing A-series (Datto engines) in the UK during the 70's had massive square port intakes. Not quite as square as the picture you showed, but definitely four sided. Janspeed produced them as their version (replica) of the GX head.

Chris I never knew this info. Ive only seen the same heads
reworked with bigger valves never the square port ones any pics?

Ive only seen these ones...
http://www.ratdat.com/?p=250

Hello D,

Here is a picture, it isn't exactly square but to me this shape would be closer to square than oval. My old man used to port his heads like this. As the caption says, this is Janspeeds equivalent to the original GX head.

Note that they use stock round port heads, which have sufficient mass to accommodate such extensive porting. Now that is interesting..... make your own GX head- Brooklyn Crack Ho style?!?

I dont think you will be abel to gain the aprouch angle that the GX head has. And allso of what I'v seen of dicected head's tere is a reasonably even thikness wall around the port and the rounder the port the better so you still might be best to take it to its limits as a round port still??

But saying that if there is a signifigent volume gain by doing this. It may be a verry good new(old) trick.

And It might be worth ya while trying to get ya hand on an a14 round port head just incase it is cast slightly diferent??


Edit: It would be good to know for every one with round port heads the maximum potential of there standard head! and maybe some geometry that people can take to there local head guy.


Edit Edit: Oh and dose a standard manifold hav enough meat to be made to suit??

Thanks a million Chris, this is what I was after for a cheap turbo setup.
I have everything I need now and this is whats referred to as D ports
much better than just square for NA setups. I guess with a turbo its
just a matter of as Jmac indicated that its better to have more charge
mixture waiting to be blown and sucked in.
Now Im off to Okinawa for 2 months and when I get back its time to get
some proper porting tools and find a Toyota Starlet manifold to allow
me to run straight out, square tubing manifold for boost.
If someone comes across a small ball bearing turbo eg. t20 size please
let me know as the VF34 Ive got recently is overkill.

That head (or one of that format) was used on an A10 race engine prepared by Janspeed.

110bhp at 10 000 RPM.........It certainly performs. How is that for the baby of the A-Series family!