Non symmetrical intakes area really not an issue, especially on a forced induction setup. Essentially you are pushing the charge in one end, it WILL come out the other.
CB Turbo systems all use asymmetrical intakes. 99% of all OEM
production cars have asymmetrical intakes, this includes ALL of your
carbureted V8’s and most out-of-the-box performance cars. Granted on an
N/A setup it will make a small difference, but even then, it truly is
negligible.
The incorrect
assumption generally made is that on each intake stroke the cylinder has
to pull the fuel all the way from the carburettor and so the
asymmetrical setup will result in a lean condition in some cylinders as
the fuel has to travel further. At face value this seems like a
reasonable assumption, but in reality what is overlooked is that the
intake is already completely full of charge and so the charge is already
present on the upstream side of the intake valves. The fuel is also
present in metered quantities (read:same distribution) throughout the
charge (remembering that it is all metered from a single point – the
carburettor ) plus the piston will draw in the required volume of charge
every time irrespective of how far away the carburettor is, as by its
very nature the volume of the cylinder is fixed.
The
other assumption is that one set of cylinders is nearer to the intake /
carburettor and so will somehow draw the intake charge away from the
other cylinders, or that somehow the charge will favour the nearer set
of cylinders. Again, each piston will draw in the same volume of charge
as the cylinder size and piston stroke is fixed, the cylinders are also
not in competition with each other as with a 4 cylinder otto cycle only
one cylinder is on the intake stroke at any one time.
The
only real difference that the asymmetrical input will make to the
charge is that there will be slightly lowered cylinder pressure at the
end of the intake stroke due to the extra drag in the longer intake due
to Bernoulli’s principle, however in reality this difference is
negligible, especially when you consider that in this case the manifold
far outflows the requirements of the intake as the tee junction is over 2
and half times the area of the stock 35mm intake valve. You would see
more of a difference on a system where the intake is restrictive (system
diameter less than intake valve size), but that is not the case here.
This also only applies to a normally aspirated engine where the piston
draws the charge into the cylinder, rather than a forced induction
system where the charge is pushed through the system into the cylinder
and all cylinder pressures are normalised at the boost level.
In
addition to this the charge is then compressed at an order of
magnitudes higher than the static cylinder pressure by the compression
stroke. The net difference is so negligible that you could not detect it
on a compression test. The larger difference is the extra work that the
engine has to do due to the increased drag, which simply results in
less power, but again, the difference really is negligible.
It is also worth noting that the characteristic of an unbalanced
engine is increased vibrations, uneven idling and uneven power delivery.
An extreme case is when it’s only running on three cylinders due to a
plug or plug lead issue, which most people have experienced at some
point. So by this very definition if uneven intake runner lengths was
such as issue, it would be easily detectable by a simple before / after
comparison and duly noted in those with direct experience. The reality
is with our systems that the opposite is experienced. The engine is much
smoother due to BETTER fuel atomisation and delivery.
Perceived
issues due to the asymmetrical intake length on forced induction
engines is basically just an internet myth perpetuated by those who do
not understand the principles of operation. Which is essentially is a
good summation of about 80-90% of all things on the internet 😀