Lawrie Anderson posted last year or year and a half about his experience
with different filters. Best drivability came with the stock filter
enclosures.
This I believe, was do to the use of the little alloy back plate adapter
(Moss 372-380). Which in effect are little 1/2 velocity stacks.
I have the adapter plates inside of the foam 1/2 sphere aircleaners and
they work well.
What's happening here is the curve of the VS or adapter allows the air
in more smoothly than the 90 degree edge of the carb.
Paul.
Rocky Frisco wrote:
> ATWEDITOR@aol.com wrote:
>
>> I'm at work now and can't check on that dent question, but let me gas
>> on about the last two.Last year Grassroots Motorsports did a series
>> of dyno tests of bolt-on MGB engine mods. One of the huge shocks
>> from their point of view was the difference--around 4%--made by
>> bolting on stub stacks to the mouth of the SUs, and letting them
>> reside under K&Ns, which also provided a power gain of around 4%.
>> Unlike standard bell-mouthed velocity stacks, the stub stacks are
>> about 1/2 in. high with a rounded opening edge that, as dealer ATF
>> products (I think that's their name--information also at home) says,
>> provides "a nice radius" for the SU carb opening. In short, I guess
>> it just fools the air flow into thinking the carb is bigger, and the
>> flow is increased. Cast versions of the stacks are around $19 each,
>> and that's what Grassroots tested. When I ordered mine, the cast
>> versions were out of stock, so I got the billet versions for around
>> $30 each. I also got K&Ns at the same time, ! going for the open
>> element design that eliminates the metal pots. I am here to tell you
>> that the combination of K&Ns and stub stacks makes a SIGNIFICANT
>> difference in performance throughout the power range, from lowest
>> RPMs up to readline, and yes, it seems to allow the ancient B engine
>> to keep accelerating at higher revs where previously it seemed to run
>> out of gas. The bill--around $200 and 15 minutes install time. So
>> here's my ultimate cheapie, no-risk, quick-install performance boost
>> recommendation: A Petronix ignition, K&N filters and stub stacks.
>> Buy, bolt and burn. Jay Donoghue72 B-GT66 Mustang (also with Petronix
>> and K&N)
>
>
> My experience confirms this; I have a single HIF6 SU on a special
> manifold on my Cooper S. I experienced a noticeable performance increase
> when I added the K&N cone filter with the short stub stack inside.
>
> -Rock http://www.rocky-frisco.com
> --
> "JJ Cale Live" CD & Video: http://www.rocky-frisco.com/calelive.htm
> The Wednesday Night Science Project: http://www.wednitesciproj.us
> Larry Spears and the Hapless Romantics: http://www.larry-spears.com
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