Dear Jim
In answer to your question regarding "through the fender" headers, I
originally purchased a set of RV8 style 4 into 1 headers obviously with the
intention of using them in the car I was building but when they arrived I
was very dissappointed in their appearance and felt that they were not
going to be very efficient at all.
So I set about desigining a proper 4 into 2 into 1 with decent diameter
primaries and long secondaries finishing in a 2 1/2" outlet, this was no
mean feat and I had to set up a dummy motor and gearbox with suspension to
check clearances. I cut out the inner fender (oh no!) in almost its
entirity to allow working room and after many hours and I think three
attempts have a very good system, which I have now made jigs for and have
many happy customers here in Australia.
Some important points to remember are -
1/ to maintain as long a lead off the head as possible
2/ get the primary lengths equal as well as the pairing correct (to match
the firing order)
Engine bay accessability was a primary part of the design in that spark
plugs were easily got at and the starter motor could be easily removed and
replaced without disturbing the exhaust, in addition the sump can be
removed with the exhaust in place (and without lifting the engine!).
Finally and most importantly the car doesn't overheat even in over 100
degree days, and mine is stroked to 4.45litre, and using a factory V8
radiator and fans.
I have flanged the joint between the primary collectors and the secondary
pipes and the tucked the two 2" secondaries neatly inside the chassis rails
prior to the chassis rail flattening out so ground clearance is maintained,
then they are joined into a 2 1/2" collector and I use a tork-tight
stainless slip joint to connect the rear part of the system, be it either a
twin or single system.
I have a template that enables the minimum aperture to be cut in the inner
guards, this I think would be less than required by the RV8 style headers.
I can send pictures if you wish.
Regards Adrian
Adrian Akhurst
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