This never showed up in my mailbox here is a shorter version
As far as CFD goes someone else can call Cosworth and tell them it doesn't
work but it won't be me. Most of this stuff was studied and documented about
80 years ago.. Taylor, Ricardo, as of recent Heywood.. All required reading
if you want a bigger clue.
The headers are part of a combination. if you have the best 4 to 1 straight
tube header is it because everything else was tweaked to work with it or
because it is better. seems people are getting cause and effect mixed up
here. maybe with the stepped header and a cam ground to go with it and a 1"
trim on the intake stacks it is better or maybe not. I do know every time I
make a big change in the exhaust system there are probably some cam tests to
go with it.
So there is no best header, best intake or best cam but there are some
combinations of them known to work well. It all boils down to running the
best flowing for their correct size heads, intake and exhaust and then cam
accordingly to keep as much pressure in the cylinder during the power stroke
as possible. if you find yourself needing shorter cams to make more power
you are headed in the right direction..
Dave
>
>
> Bryan;
> So far I haven't seen any A-B comparison data presented on header
> performance re: stepped tubes, conventional tubes, anti-reversion
> devices, etc. Comparing data from different engines on different dynos
> is not very helpful: most magazine articles don't do good comparisons if
> they present any data at all.
>
> Regards, Neil Tucson, AZ
>
>
> Neil,
>
> CFD ?????
> In looking at some headers made to fit real tight areas, I wonder
> how the actual behavior of the fluid flow and the shock waves
> could be predicted or modeled. I would be surprised if current
> CFD models would be of any use. It's looks like it's just too
> chaotic to describe mathematically.
>
> Bryan
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