Resolved Port Matching 2G Head to FP Exhaust Manifold

[aaronth777]

I've been running an FP exhaust manifold on my 2G 7-bolt head to my e3 16g turbo for a few years now and it's ran great, but a question occurred to me recently.

The FP manifold is compatible with both 6 and 7 bolt heads, so obviously the ports on the manifold are made bigger to match the 6-bolt, but doesn't that mean there is a step change going from the smaller 7-bolt ports to the larger manifold ports? It's a step bigger so it isn't as big a deal as a step smaller would be, but wouldn't it still cause turbulence?

I am pulling off the manifold, turbine housing and o2 housing soon to get them ceramic coated by Swain Tech, and want to see if I should match the 7-bolt exhaust ports to the manifold so I can do it while the car is apart. I'm aware that porting the 7-bolt head is generally not recommended until higher hp levels, and it is optimal for exhaust gas velocity as it is now, but I just want to see what others think.

I've searched through all the threads I can find but none of them seem to really answer my question, they usually focus more on the benefits of the FP over the factory 2G or EVO manifold. My apologies if this has been answered already and I just missed it. I did find threads about port matching to a 1G manifold, but the FP manifold is way more efficient and I didn't see it answered clearly.

 

[DSMPT]

I think you are confused between intake ports and exhaust ports. 6 bolt larger and 7 bolt smaller ports are referring to intake ports, not exhaust ports. The exhaust ports technically have no difference.

 

[aaronth777]

I think you are confused between intake ports and exhaust ports. 6 bolt larger and 7 bolt smaller ports are referring to intake ports, not exhaust ports. The exhaust ports technically have no difference.

Oh... if that's true then I did a lot of research for no reason . I know the intake ports are very different on the 6 and 7 bolt heads, I thought that applied to the exhaust ports too.

 

[DSMPT]

Oh... if that's true then I did a lot of research for no reason .

Yeah

I thought that applied to the exhaust ports too.

6 bolt and 7 bolt even share the same exhaust gasket. It's just the 7 bolt exhaust side has 2 larger diameter studs bolt at the corners, so some aftermarket exhaust gasket bolt holes would need to be modified when installing.

 

[aaronth777]

Yeah

6 bolt and 7 bolt even share the same exhaust gasket. It's just the 7 bolt exhaust side has 2 larger diameter studs bolt at the corner, so some aftermarket exhaust gasket bolt holes would need to be modified when installing.

Ah okay, thank you for clearing that up! Just another case of me overthinking things haha