Re: header flow
i was just thinking in regards to spool time. and a well balanced turbo systen can get to a 1 to 1 pressure ratio
Maybe if you have an Indy car or a high rpm ricer burner. At 1:1 ratio you are actually running the turbine off heat instead of pressure. You will not get one of our turbo setups there. If we could acheive 1.25 with our setups it would be great. I would think most of our builds end up in the 1.7:1 to over 2:1 range. Of course there are different ratios at different times dependant upon boost, load, rpms, timing, heat etc. An indy car can acheive 1:1 because of the high steady rpm at WOT. They take forever to spool though.
As far as the design in your header. In spool time I still wouldn't think it would make much difference. Differences in timing and cam setup would be more noticable.
I remember back in the early ATR days they were selling the fact that their headers would be a big plus on the top end , but would sacrifice some spoolup. I did ATR headers as an only change back when I already had some other mods including a pte44 turbo setup. I noticed no change in spoolup over the stock manifolds. We have also seen stock manifolds go 9s. Even for spoolup the back pressure in the manifold has to be in effect in order to increase the inertia of the turbine wheel speed. One would think less turns and bends would be perferred, but for our applications I doubt if the sharp corner has much of an effect.
John
