Porting stock intake mani

drew10101010

drew10101010

Greenie N00B Member
Greenie Member
So we all know the stock intake mani has terrible balance. As can be seen the table cyl 4 is the worst followed by cyl 1. What if we just port cyl 4 and 1 and leave 2 + 3 unported. Would that work to balance it?port.JPG
Or porting near the entrance so cyl 4 doesn't have to make as sharp of a turn. I wish I had a flow bench so I could actually test this out.
manifold.JPG
 
So reading more threads:
https://www.mazda6club.com/threads/ported-intake-manifold-before-and-after.222923/
https://www.focusst.org/threads/stock-intake-manifold-flow-data.25992/
Seems like there is a big nub on port one that can be taken out. Also gasket matching. I think I'll just do it too. Remove vtcs, gasket match, leave middle ports alone and work on the cyl 4 path near the t/b.
port1.JPG
Here SPEED PERF6RMANC3 got some different numbers with better balance which is quite odd since they ported the middle two but the numbers didn't change for runner 3. Runner 2 went up slightly. But 20% vs 14% balance. They also concluded the ST manifold is very good so I'll probably get that at a later date. For now I'll just mess with the stock mani.
 
There are ridges on the insides on the ports with blades in them. I am working on porting a stock manifold now. The bump in cylinder 1 is pretty damn big and difficult to remove while simultaneously trying to maintain a port shape/floor similar to the other cylinders.

I started with CP1 simply because the bump was that crazy to remove. Here are some pics from when I first started porting it with the throttle shaft removed.

Vbg8eZN.jpg


MrpuQ61.jpg


CP1 hump partially removed
ABzxmKa.jpg

This isnt a finished port, just had cleared most of the shavings out for a better view. Bump is 80% gone in this image

rPZNprP.jpg


I have been working on this manifold still and have newer pics. Get yourself some Dykem or Prussion blue to mark the ports if you're doing a gasket match. The purple sharpie I used before rubbed off and I had to reapply it. I ended up buying some good marking compound and it is a lot easier to see when porting.

Good luck.
 
Looks good! It's going to be a while before I can get started as I'm still waiting on my pistons to come in from backorder. And still I need to get state inspection and emissions so I need to pass those first without touching anything then I'll port it lol. Gonna be a minute.
 
drew10101010 said:
Looks good! It's going to be a while before I can get started as I'm still waiting on my pistons to come in from backorder. And still I need to get state inspection and emissions so I need to pass those first without touching anything then I'll port it lol. Gonna be a minute.
Click to expand...
If fmic, I have my pnp in the FS section all done.
 
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