You keep writing this. But one source tells me that the rounded

edges of

the bell mouths is the key here, not just the bell shape.

Finn

Finn, I did a lot of webber tuning in my race days. They tested a bellmouth and radius and a
simple trumpet. The finding was if there weren't large obstructions close to the inlet one was as
good as the other. The full radius item was real exotic though, and was sold for several years.
The edge rolled all the way around 180 deg. The carbs with narrow bore spacing wouldn't even fit
them. The basic trumpet shape worked just as well. Mazda would have fitted a full radius if it
would have done anything. Check out the intake on the Le Mans engine on the acre site. If you are
going to all the trouble of building a varible intake you use the best possible shape! Bill Jepson

What you don't see in this picture is the huge plenum air box the variable length intakes
operated in. Made necessary by the fact the bells moved in and out up
to a max of seven inches.  The difference between being tuned at 6250 RPM
and being tuned at 8250 RPM. My guess is the total length at 6250 RPM was
about 14 inches. At 8250 RPM it was about seven inches. Therefore the air
in some case had to flow from behind the bell as Bill mentioned above.

Paul Lamar

Here is a picture of the Lemans race car's huge air box plenum.

Paul Lamar
 
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