>I bought the Solex one with 50mm air horns underneath from Dean. Never ran
>the stock ones, so I can't help you with a comparison. But the Solex one
>looks nice and appears very functional with the huge foam area, should be
>very free flowing.
>
>Have heard Ross of Sports Imports mention several times that he got a
>*much* bigger boost over the stock air box by running two 2000 Solex air
>filters bolted on top of each other. So I suspect that at least the Solex's
>are choked by the stock air box. Not sure whether the SU's have the same
>problem or not.
If you use an air cleaner that's basically two flat plates with an open
element between them then you need some sort of an air horn or radius to
smooth the air flow into the carb throat. The length (height?) and
relative benefits of different lengths is open to (frequent) debate.
As far as the type of elements are concerned, I personally am very
partial to the cloth K & N type which I think they flow as well, filter
better, and last longer than foam elements. I usually decide on the
height of the filter element by adding the diameter of the carb throat to
the length of the air horn, so on a 44 mm carb running 25 mm air horns, I
would use a 2.75 to 3 inch element. It just makes sense to me that
keeping a clear space in front of the carb throat at least equal to its
diameter minimizes flow restriction and turbulence. APT and TWM (along
with others, I'm sure) offer a number of different sizes and shapes of
elements.
The 3.5 inch high/6 inch diameter (round) K & Ns that I bought for my 38
mm SU's with the 10 mm air horns are probably way bigger than they need
to be, even for an L-20b street motor. In fact, I may use them (the
elements) on another motor I'm putting together that'll be running a pair
of 40 DCOE Webers. This motors will be a more RPM oriented L-18 for the
E/Prepared autocross car.
Both of these setups are open element with (for now) no direct cold air
feeds. I'd think that you'd still want to maintain plenty of clearance in
front of the carb throats using a closed cold air box to isolate the
carbs from under hood heat. some folks will build such a box and then
use a remote mounted K & N cone style filter. TWM offers a box like this,
but I remember it being rather pricey. Shouldn't be that hard to
fabricate and much cheaper if not as pretty.
FWIW, Ron
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