exhaust port dimension?

[TeamM3]

the factory US head intake port dimension is well discussed as being a 26 mm throat diameter.

Can anyone tell me what the exhaust port throat diameter is?

TIA

///MS

[TeamM3]

somebody on the SIG measured 31mm on the exhaust side, just FYI for future reference

here's a photo from another thread that shows the dimension on the intake side:



Mark

[HANDBLT]

Originally posted by TeamM3
somebody on the SIG measured 31mm on the exhaust side, just FYI for future reference



Mark

Now that you posted that picture, there are a ton of pics where somebody cut open an S14 head in a few different places and he measured all of it. Do a search, it is on here somewhere.

T

[TeamM3]

I did a search, that's where the picture came from (note the words "from another thread"), but no dimensions for the exhaust were shown there or anywhere else I searched, including the SIG archive.

The stock exhaust port greatly outflows the stock intake port, so nobody usually messes with the exhaust port until building all out racing engines. There's not much info on it as a result.

[Mmark]

Originally posted by TeamM3


The stock exhaust port greatly outflows the stock intake port, so nobody usually messes with the exhaust port until building all out racing engines. There's not much info on it as a result.

That is typical for the German designed 4-5 valve heads of the mid 80's to early 90's as they wanted to preserve as much low end torque as they could by trying to increase the speed of intake flow rather than outright volume of intake flow.
The 1.8 vw 16v had large intake ports and as a result barely more torque than the 8v, When they introduced the 2,0 16v they changed the port configuration to a decreasing port diameter from the outermost end of the intake port to the valve throat.

Now they have the options of changing the valve lift and duration via management controlled cam timing.


Uwe had the Head cut away pics thread but no port dimensions.
m.