Squaretop manifold porting
 

Well pretty much everyone said not too, but I went ahead and did It anyways.
I ported the egr expansion chamber on my squaretop intake manifold and matched it to a 64mm throttle body.
eventually I would love to test it against an unmodified one because ive not seen much info about doing any of this.

Please also view my thread on modifying the VVT PCV system:
https://www.miataturbo.net/engine-pe...4/#post1567859
https://cimg3.ibsrv.net/gimg/www.mia...0d5d6a6eef.jpg
https://cimg8.ibsrv.net/gimg/www.mia...d7cecd75a1.jpg
https://cimg6.ibsrv.net/gimg/www.mia...4c0fe8760a.jpg
https://cimg0.ibsrv.net/gimg/www.mia...e0c8c8a953.jpg
https://cimg2.ibsrv.net/gimg/www.mia...68927d9549.jpg
https://cimg4.ibsrv.net/gimg/www.mia...bd8c6af9f9.jpg

Interesting! I was looking at this same thing when I opened up the throttle body port for the Skunk throttle body. How did you reach in there to remove the EGR expansion chamber?

I didnt find any info about porting anything besides matching the TB, I tried a few things, at first before I understood how thick the metal is. Its like 1/4" -1/2' thick in spots so It started with a grinder, then I swaped to a drill and followed the lines i stared with the angle grinder. then I used a jig saw with a metal cutting blade and that made pretty short work of the bulk of the metal along the sides.
the biggest problem areas are the "hump" of the egr chamber where it meets the Throat is the thickest. but you can reach a grinder in there so its not that bad. but the worst is the center section between the ports and egr chamber that gets left because you cant get enough angle either going through the ports or the now open egr chamber. so im still working on it
https://cimg3.ibsrv.net/gimg/www.mia...c75c201673.jpg

i port-matched mine as well, because otherwise your effective diameter will be even smaller than with the stock throttle body. Fluid dynamics are a bitch. I did however no go beyond that point because I saw little relevance. I trust the engineers at Mazda to have developed a manifold with optimum volumen and a Helmholtz resonator, and I suppose their skills are better than mine. I have yet to see an intake that is performs better overall than the cheap and proven squaretop. IFAIK not even the Skunk2 performs significantly better.

Pics of my port-matching:

Instagram

View this post on Instagram

I would agree about the Skunk2 being inferior to the squaretop, and that yes mazda has spent much more time and money thinking about it than i have in a few weekends with a grinder. but,
If this does anything besides have a noticeably negative ill be happy.

In for dyno runs.

+1 on in for dyno numbers. Curious to see how this will affect your torque. What supporting mods do you have to the engine to play along with this?

its hard to say since my engine is on the stand, but I have bought a few things the most important things being that its a vvt with an