Silenced vs. Un-silenced air cleaner for 340 small block

[dakota]

I don't think this is a huge deal, but I'm curious if anyone can explain the pros and cons of a "silenced" air cleaner (with snorkels) vs. an un-silenced version.   My 340 has an air cleaner similar to what's in the attached picture which I just pulled off of eBay.   In the past, I've only seen air cleaners that have either snorkels coming off the air cleaner or seeing something completely open around the air filter perimeter.   The eBay ad referred to the type lacking snorkels as "unsilenced."   Any historical perspective would be appreciated.

[Topcat]

Only made for a few years. 69-70.
68' and prior were smaller ones.

Really just a marketing ploy to market high performance I would think.

I remember in the early nineties the smog tech was telling me it was an illegal air cleaner.
I had to educate him.

[cudabob496]

sure looks like it would restrict airflow, and hurt your power output.

[Topcat]

By late 71' the government was beginning to look harder at the automotive industry emmisions.

The TAC also known as the Thermal Air Cleaner was already being used prior to or around 1970.

The reason was faster warm ups meant less emissions on cold starts.
On the snorkel part underneath is the TAC. The big 3 began putting the TAC on all cars by 72'.

I don't recall any make/model without TAC from 72' and after.

[cudabob496]

for a small block, can't get much better than a 14 x 3 open air cleaner with a K&N filter.

[Bullitt-]

listing w/application ....you have one of the most desirable from what I gather

http://www.nicksgarage.com/aircleaner.htm

[Chryco Psycho]

I agree it has to do with emissions mostly , un silenced was less restrictive but had no provision for hot air / heat risers , it woul dhave been tough to get a car started @ - 40 with an unsilenced air cleaner & keep it from icing the carb

[Aussie Challenger]

There is nothing as good sounding as an un-silenced air induction system at full throttle, having said that using a larger air cleaner with ducting to the outside therefore only allowing cold air into the induction system is the best for performance.   
Cold air equals more dense air into the carburetor, more HP, hot air from under the hood on an open air cleaner means less power, they may look good but not as efficient as the cold air pick-ups.   
I really do like the induction on my Little Red Express, going to do similar for the '70 Challenger.   

[cudabob496]

There is nothing as good sounding as an un-silenced air induction system at full throttle, having said that using a larger air cleaner with ducting to the outside therefore only allowing cold air into the induction system is the best for performance.   
Cold air equals more dense air into the carburetor, more HP, hot air from under the hood on an open air cleaner means less power, they may look good but not as efficient as the cold air pick-ups.   
I really do like the induction on my Little Red Express, going to do similar for the '70 Challenger.   

have one of these on my Cuda. For every 10 degree drop in air temp into carb, you get about a 1.5% power increase.
So drop it 50 degrees , and that's 7.5%, or 30hp on a 400 hp engine. I've got two snorkles running to front of car, which
also gives you a positive air pressure into carb.

http://www.ramairbox.com/install.html

Nother way to look at it, say under your hood its 100 degrees hotter than outside. If you draw hot air into carb from under hood,
that would reduce your power by 15%, or 60 hp, on a 400 hp engine!

Thats why all the little rice rockets have cold air intakes. But they are only getting about a max of 10 hp increase, because
they are small engines.