Ok so today i finaly got back around to stripping my spare NA head and i thought id share my findings and insights
1st here's the mess. Not the best of ideas using the kitchen table if you have another half and treasure your wedding tackle!
Now before i talk about design theres the ovious differences such as different cams. The exhaust cam has a ring on the end where it meets the distributor which picks up cam position unlike the TT which uses a seperate CPS sensor on the intake cam to detect cam postion.
Not to sure about the valvetrain as i dont have TT parts here to compare to.
Now onto the actual design.
1st thing i looked at was the intake ports.
Now i know it isnt the best picture in the world but they appear to be fairly smaller than TT ports but also higher up the head with a slightly steeper angle.
Then i looked at the exhaust ports.
Again not the best of pictures but it was hard to get a good shot.
They seem to be larger than TT exhaust ports which suprised me as i would of thought larger exhaust ports would be better suited for turbo applications?
Moving on to the combustion chamber design.
The NA head has about a 0.023" recessed surface that's cast into the combustion dome
For the GTE head, however, the combustion dome is flush with the bottom of the head.
The difference is IMO the GE valve/piston clearance is shared between the head and the piston resulting with the very thin HG on the NA.
On the TT however the HG is much thicker,about 1.3mm, and again IMO may account for most of the piston/valve clearance on the GTE design.
Thoughts and opinions guys?