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and what are your thoughts on the poss effect, cutting the round exh port into a slight D shape like the turbo manifold inlet port i bought?
well here are some better pics... i hope.... to see if i made a rookie mistake and not saying i didn't as this is my first attemp....hence the spare head lol this is the intake side. does the same principal apply for the exh port just under valve seat?
gotcha and re read what you said about intake port. the top side right under the valve seat should have about a 60* angle vs the rest heading down. if i understand that correctly.
i went and looked at the unmolested factory head. i see exactly what your talking about now. that angle on the factory head extends below the valve seat about 1/4" to 5/16" and only is found on the back side directing the stream into the middle of the combustion chamber. i learned something today!! i cannot take a good pic that will show it as i tried but ........ anyway the majority of that angle is still there but i did blend into it but not by much basically took the sharp angle off of it. i can see it and feel it with my finger. now the exh port is a diff story where it is still mostly there i did take more out on the exh side. the exh port coming out of the head is still slightly smaller than the header inlet port, i didn't want to open it to the full size.
Most 5 angle valve jobs run something like this,15/30/45/60/75,top to bottom. Blending angle into angle makes for happy airflow. The seat should be a true 45 of around .060-.100 wide. Turbo use ,I'd like to see it near the .100. A wider seat helps cool the valve. On the intake side .040-.060 wide.
The word of the day is "boundary layer"....... Well, 2 words......Skip the 5 angle on the exhaust side and go full radius.
This leaves no margin of heat transfer. You are not going to gain that much more HP and we are not talking cutting seconds from a quarter mile time.
CORRECT! On a turbo engine especially,a slightly wider than usual seat is a necessity.