Rick/Craig
Yesterday I stared into the engine bay of my "in progress" RoverV8
converted MGB GT. It has Australian built through-the-fender exhaust (see
picture) The first thing you notice is that 2/3rds of the exhaust header
is now outside the engine bay as compared to "hugger" types. So less heat
generation in bay. The second is that the flow path of air now will more
likely flow over the pipes and out of the hole created for egress of
pipes. Thus wafting away the hottest of hot air. The third and possibly
the last thing is that the hole is higher than the hole under the
engine. This means it is the path of least resistance and will tend to
pull out more air than an equivalent sized hole under the engine.
At 12:22 PM 8/4/01 -0400, Rick Huber wrote:
>Craig,
>
> >From an aerodynamic point of view, the high velocity air rushing by the top
>bottom and side of the car is what creates the low pressure area, the same
>principle that enables airplanes to fly. I've heard other people say that
>cutting holes in the wheel wells allows hot engine air to escape, but air
>already has to be escaping as fast as it is coming in through the radiator /
>front of the car anyway. However, with that air forced into the engine
>compartment from the front, cutting holes in the wheel wells should create a
>positive flow from the engine compartment into the wheel wells from the
>principle of the air rushing by on the outside as well as the air forcing
>itself
>in through the radiator. I think there is more area for air to escape out the
>bottom of the engine compartment than you will create by cutting holes in the
>wheel wells, so the air flow should be relatively small, with relatively
>little
>pressure difference. I don't believe the foot area would vent outward into
>the wheel well, since the cockpit is open to the air rushing by on the
>sides and
>the top already.
>
>I think the real key for removing heat from the engine compartment with the
>wheel well headers is that the hot exhaust pipes are now out of the engine
>compartment giving off heat to the environment outside of the engine
>compartment.
>
>Cheers,
>
>Rick
[demime 0.97c removed an attachment of type image/jpeg which had a name of
Exhaust on show.jpg"; x-mac-type="4A504547"; x-mac-creator="4A565752]
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