I understand what your trying to do
but you are only looking at part of the details required to get the ULITMATE manifold performance
no mention at all of induction tract --this too will need to be considered to get best compromise on ex manifold
then there is the actual ex system and where you will place your first expansion box .
but why do this with a std cmashaft spec as the real world diff on power is will be a small number .
I have done all you are trying to do when we raced the 1294cc 8v
which is hwere we came up with our 4-1 manifold design ,
all your hard work will give little gains unless you look at the WHOLE engine and set goals to where you want max torque + power before you cut one piece of piping.
take a look at std inlet manifold and straighten it out and see how long it actually is --it will suprise you and then look at t/body manifold and how short --
people will claim that t/bodies give more torque -thats not so --yes with dif cams + togther engine mods which raise total bhp (which is a combination of torque+rpm )the result may be more torque ,but just fitting t/bodies to a std spec engine will not give more torque at same rpms as std manifold .
this is why we made the downdraft t/body inlet manifold to make it as long as possible with no bulkhead mods .
our own ax have the bulkheac cut out to maximise the torque --it was 18" from trumpet to head ,. we were made to remove it a year later after winning the championship for a thrird time --the redyction in length by 150mm dropped max torque by 10lbs ft .
so your first job is to state at what rpm you want max torque and at what rpm you want max power --then with a cxombination of cam + inlet size+length
and ex size+ primary lengths +expansion in correct postion you will get what you want
look at the forums now every one promoting certain well known ex systems --they don,t even have a first silencer box and the ones that do don,t have them in the correct postion --
why cos it,s cheaper to make a system with one box --but the forums will tell you that they are the best .
I get accused by lots of people including you in the past,of being superior and just like to see my own posts --that has never been the case and i try to help .
If the car maker who knows more than me --if only because they have unlimited development facilities + money fit 3 boxs on the system ,then there is a good reason,as they try to get the best compromise of power + economy (which is effiency) they have shown you the basics to work with especially if keeping std cam.
anyone reading this with a single box system will have noticed at a certain rpm --around 60-70mph there is an anoying bumming noise from the ex system --that is because the harmonics of the gas at that rpm is not happy ,which also cuts power .
fit a front box in correct postion and it will go
.
so along with your ex + inlet manifold calcs you need to add ex system design and don,t make it too large a bore until after the first box.
the std GENUINE vts system is very good
I even did a test one day on a car with t/bodies +around 150bhp and swopped the after market ex for a s/h genuine vts sytem --the power did not drop .
yes the car had a 4-1 manifold and no cat --but so did the aftermarket system .
I then fitted a btb complete system and the power rose very slightly --not because of the dia ,but it had a first box to replace the cat as the power it made did not warrant such a large bore system
the point I am making is at least haalf the tuning parts availble are for "bling" and mix + match things at your peril .
I remember a very famous heated debate on manifolds a few of years ago and someone was going to do a proper back to back test on all the manifolds avialble .
I even offered a btb for them to test and free use of my rollers if they did all the swopping of the manifolds and i would even tweek the ecu for best output at a single rpm for free thats howconfident i was.
needless to say a true test never happened ,but the bullshit factor came to the top claiming the raceland to be the best .
the piper design manifolds are actually my designs for both 8 + 16v engines as I actually sent them cars to make the mnaifolds on along with ny spec for sizes +lengths --along time ago . and yes you say the primary lengths are not all identical ,but for normal rpms the very slight diffs make no diffenerence
I do not stock btb anymore --pricing has gone silly ,but still stock pipers and have a few btb 8v mld steel manifolds left at very special price .
I wish you luck with your endeavours but unless you do all the maths for the exact rpms where you want the max torque and bhp it will always be a compromise .
if looking for another book to read "fourstroke peformance tuning" by A graham Bell ,its a haynes book , is as good I have found that is easily readable--yes its an old book ,but as I have said many times before physics hasn,t changed
