>>> There may be an inherent higher level of "noise" with tube
>>> type headers, simply because they do not have the mass that
>>> the cast iron exhaust has, which will tend to absorb quite
>>> a bit of exhaust noise.
>>
>> Agreed ... cast iron also does a better job of absorbing heat,
>> so a tubular header will increase engine bay temps ... not a
>> good thing as high engine bay temps decrease power output.
>>
>> See Post on ram air ...
>
> True. Which would be the only reason I have considered cobbling
> up some type of Ram Air. Not so much for the "ram" effect, but
> to ingest a cooler charge of air.
>
> If I ever do such a thing, the system would have to be such that
> the presurrization at speed would be minimized, to avoid the carb
> calibration problems.
I've been working on a 'cold air box' to reduce the impact of the
'A's engine bay temps ... like any engine, as the inlet temp
increases the power fades rapidly. The 'A' is fitted with a cold
air hose, but it stops at the radiator support ... current thought
is fit a K&N filter to the end of the existing hose and extended
the hose from the radiator support to a sealed box (with K&N stub
stacks) fitted to the carbs ... very similar to the 'cold air box'
that is fitted to the A.H. 100S. I trying to come up with a box
that will accept the existing 4" hose, fit into the limited space
in the 'A' engine bay, and that I can easily fabricate ... its the
later that is giving me the most trouble ... ;^)
Fitting a sealed air box with a good internal capacity and a cold
air pipe that protrudes into the box will create a similar 'ram'
condition. Since the air pipe protrudes into the air box it
creates a step that allows the pressure pulses to travel inwards,
but deters them from being able to reflect back out. This helps
the incoming air as there aren't any negative waves resisting
incoming flow, and adds a pressurizing effect. The 'ram'
condition is created simply by air moving through the pipe into
the box (drawn in by the induction process) ... not because intake
for the cold air pipe be exposed to air flow (pushed in by the
movement of the car) ... so its predictable and tuning the SUs
won't be a problem.
I'm also serioulsy considering having the cast-iron exhaust
manifold JET-HOT coated.
Check out ... http://www.goracing.com/jethot/sitemap.html
> Safety Fast! ... larry.g.unger@lmco.com
> '61 MGA 1600 MkII
>
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