I plan on drilling a 1/3 bridgeport into the aux ports on my NA. I was wondering if anyone on here had done this, and could give me any suggestions or feedback on it. How many holes, what size, what placement. I know to a degree it all depends on how much I want it to flow, but the idea is to leave it strong and keep the seals in place.

Any input is greatly appreciated.

Thanks
Dave

Edit: By the way, this is not a "quest for power." This is mainly for an intro to porting for me.

 

Ok, so for the sake of actually getting someone interested in the thread it's probably a good idea to ask about a half BP instead of the largely-useless-as-NA-1/3 port.

I know that no matter how I do it I want 550 secondaries, collected header & full exhaust, at least an RTEK 2, and at some point down the line a custom intake manifold.

For now though, my interest is in the actual porting.

I suppose that this isn't the worst place for me to also ask peoples opinions on "closing a half bridge" with individual throttle bodies... one primary 2 secondary that open later.

 

Just do your layout very carefully so you don't cut into the O-ring groove or the water jacket.
If you do intend to bevel into the housing, only do that to one side.
You will need the other side of the housing square to support the end piece of the apex seal.

 

FWIW: Here's another way to get earlier intake opening.

 

Am I looking at port phased rotors?

I am only looking to do work on the Irons. I plan on leaving the housings/rotors alone. Port phasing is tempting, but I don't have what it takes to mill/balance those. I do have a drill press and plenty of air tools though.

I think that I may go pretty tame on the holes and essentially do a "half bridge" worth of porting on all 6 ports.

That way the corner seals and apex corners have everything they need to stay happy, and I have the flow of at least a half bridge.

If you know something I don't about port phasing though do tell. As far as I know there are few shops that do the phasing and even fewer that properly balance them.

Thanks for the input.

 

That's the best way to do it. There's no doubt that the 1/3 bridge works in a turbo application, but I don't think anyone has shown any real gains in an NA application. With a turbo car, the increase in turbo response is unreal.

I describe the basics of how to form a bridgeport in this thread:
https://www.rx7club.com/forum/showthread.php?t=328090

While I'm not familiar with it, is the RTek not just a modified stock ECU? Unless the RTek gives you full control over timing, fuel and split, then you're going to want a standalone. Also you will probably max the AFM as far it's measurement capability if you have a half bridge.

And as you guess, the stock NA intake does not play well with high overlap ports. That last bridgeport I saw with a stock NA intake ran like utter crap.