Sometimes I think it's a whole lot easier living in Australia - you
people up North have too many choices and too many tough decisions to
make! Here we tend feel grateful to find ANYTHING to solve a problem.
Nonetheless, I had an interesting experience involving this subject.
When I bought my TR3A, it had already been raced for 15-plus years. It
had a couple of ram tubes which I still have, and I just went down to
the garage and measured them - about 3 1/4" long. They had no form of
filter. Feeling reluctant to run without any filter, I installed some
"sox" as they are know locally. Simple foam cylinders, given form with
a spring inside, they are the the "standard" filter used on just about
every race car in this part of the world.
So, fitted out like this, I went to my first race meeting, headed out
for my first practice lap, and "putted" slowly around, just making it
back to the pits. This is a few years back, so I can't remember what
revelation led be to removing the "sox", but having done so revealed an
engine that would now actually get me around in at least a far less
embarrassing rate. I ran the rest of the weekend happily "sans
filters".
Some time later, the car went for it's first chassis dyno tune. They
were reluctant to run it without the sox, and lo and behold, it was
fine. So back to the track, sox back on, first practice lap and ....
"putt, putt, putt" - same old problem.
To make a long story short, those long stacks, the filters and the
close proximity of the inner fender well just didn't allow enough air
with the bonnet down. But, in the garage on the dyno, running with the
bonnet open, all was well.
Happy ending - I now run short (1 1/4") stacks, with sox, quite
happily. BTW - these new stax have nicely rolled edges which may also
be making things better.
Hope this adds something to this obviously vexed subject.
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