You forgot to take into account the valve stem.
If one has the newer 7mm valves in the 1.9 head you get flow a flow area of 979mm^2 and one a 1.6 with 8mm stems you get 857mm^2
That's 14% increase in flow area right there, also port design is better on the 1.9 heads.
Right I had to just post quick and jump cause I was at work haha. But u showed what I mean, a tiny increase in valve size is a major increase in flow potential. I didn't really think of it like that till I ported my head and calculated the flow area just by opening the oval 1mm all the way around
i went to the 1y engine because i was told that the valves had 7mm stems...
bad thing that of being hard or expensive to increase compression,i was tempted to do a weird franken engine,just because...
drop a 1.6 head on it if you want more compression..
You forgot to take into account the valve stem.
If one has the newer 7mm valves in the 1.9 head you get flow a flow area of 979mm^2 and one a 1.6 with 8mm stems you get 857mm^2
That's 14% increase in flow area right there, also port design is better on the 1.9 heads.
Not kicking up dung, but from what my machinist says the D shaped port vs the hydro O port there is no gain. If anything he likes the O port better to start from. He has flowbench #s that support that and he had done 1.6 O port with bigger valves. Granted every head is cast a bit different, but the O port head he said will usually win if the valves are the same size. Again, from his data and the math done the real deal is in the valves.
I forget what this thread even started at???
Flow benches can give you the answer you want it to give, It's just a matter of how you set up the test. It's not just the entrance shape of the port that is different. Does he flow test with the correct bore size and with the inlet manifold?
Off course your guy gets better numbers on O shaped ports, he is used to working on air cooled engines
The valve spacing is different on the 1.6 vs 1.9 head so there is room for bigger valves in the 1.9 head, big advantage if going all out!
Flow benches can give you the answer you want it to give, It's just a matter of how you set up the test. It's not just the entrance shape of the port that is different. Does he flow test with the correct bore size and with the inlet manifold?
Off course your guy gets better numbers on O shaped ports, he is used to working on air cooled engines
The valve spacing is different on the 1.6 vs 1.9 head so there is room for bigger valves in the 1.9 head, big advantage if going all out!
I thought some of the advantage of the 1.9 head was the shape of the intake port its more of a straight shot to the valve the 1.6 is more curved looking. I just mean maybe that has more to do with it than d vs o, just speculation. I would think the d vs o is probably not much difference especially when ported 8v gassers are made to perform for sure. A local machine shop told when I was asking about bigger valves that u can actually buy off set valve guides and such to help with spacing which would help if using a 1.6 head and let te 1.9 go super mega large on valves haha
Yeah, that is kind of what the machinist was saying trev. It isn't about bigger port, or straight shot, it is about velocity. If you speed up the air right as it enters the cylinder that is best. He seems to think the hydro 1.6 head has the best shape for that as cast and after porting.
....in other news, my head is being welded as we speak. I will post flow numbers when it is in my hands.
i went to the 1y engine because i was told that the valves had 7mm stems...
bad thing that of being hard or expensive to increase compression,i was tempted to do a weird franken engine,just because...
drop a 1.6 head on it if you want more compression..
that is a normal engine...
for start it must be 1.9 head,seems that best way is to stick with 1.6 bottom...
So....any updates/experiments with chamber coatings yet?