Removing 1975 CIS air box?

mreid · 06-07-2013, 10:50 AM

The question is, can I and replace it with a k&n cone filter? I know some 930 owners have done this, but not sure on a 75 CIS car. If so, what other changes are required?

86911tlcab · 06-07-2013, 11:27 AM

obviously you just mean the air filter part...you cant remove the entire airbox and replace with a cone filter...what would the runners attach to?

mreid · 06-07-2013, 11:52 AM

Sorry, yes the air filter housing.

allaircooled · allaircooled's Garage

I don't know how you would do this with a cone type filter, but if you want a K&N filter they make one that fits in the original housing.

DohertyCM · DohertyCM's Garage

They also make a carbon fiber cover that replaces the stock cover, and it looks really nice and allows for more airflow.

don gilbert · don gilbert's Garage

the cis airbox is a tuned piece of equipment. The snorkle acts as a velocity stack speeding up the incoming air. Modifying it by sticking a cone filter on the end will be sure to make less horsepower, plus, I wouldn't put a kand n on my lawnmower.

boyt911sc · boyt911sc's Garage

Mreid,

Were you the guy from Wester Chester that moved to TX? Someone gave me a new K & N air filter and never had a chance to use it. It is still in its original packaging (new and never installed). If you need one, you can have it just take care of the postage. How is your new home?

Tony

CountD · 06-07-2013, 01:52 PM

Quote:

Originally Posted by don gilbert

I wouldn't put a k and n on my lawnmower.

Words of wisdom. I can't stand those things.

DohertyCM · DohertyCM's Garage

Quote:

Originally Posted by don gilbert

the cis airbox is a tuned piece of equipment. The snorkle acts as a velocity stack speeding up the incoming air. Modifying it by sticking a cone filter on the end will be sure to make less horsepower, plus, I wouldn't put a kand n on my lawnmower.

Pretty funny, I had a performance increase with mine...and if you look on some of the stock covers, some of them were larger than others (the early ones were longer and smaller diameter and the later 2.7's were shorter and larger diameter)....you don't get a performance increase by sucking air thru a straw. Velocity stacks are long and straight and allow the air to be less turbulent when it enters the heads.. this makes for a better, more even atomization of the fuel, which allows for a better combustion cycle.

K&N's are good if used and cleaned properly. Since you don't have a Mass airflow sensor you should not have any problems with this if you get sloppy with the cleaning and re-oiling.

Ronnie's.930 · 06-07-2013, 08:43 PM

Quote:

Originally Posted by don gilbert

the cis airbox is a tuned piece of equipment. The snorkle acts as a velocity stack speeding up the incoming air. Modifying it by sticking a cone filter on the end will be sure to make less horsepower, plus, I wouldn't put a kand n on my lawnmower.

Quote:

Originally Posted by CountD

Words of wisdom. I can't stand those things.

You gents must not have used them properly - I've used K&N filters for 25+ years on cars, racing motorcycles, and a 7.3l diesel truck (for 15 hard years and counting) and have never had a problem with a single one of them . . .

Ronnie's.930 · 06-07-2013, 08:58 PM

Quote:

Originally Posted by mreid

The question is, can I and replace it with a k&n cone filter? I know some 930 owners have done this, but not sure on a 75 CIS car. If so, what other changes are required?

Not really answering your question, but the 930 CIS metering assembly is a "suck through" design (air is drawn over the metering plate via the intake demand) and I believe this is much different from the way the non-turbo CIS metering assembly operates. In other words, as long as it is not restrictive, what you put on top of the 930 metering assembly (cone filter, OEM airbox, etc) has almost no measureable effect on performance. This has been documented by several people that have done back-to-back dyno tests of various filters and such. Again, just a bit of general info as I know you are not asking about a 930 system . . .

don gilbert · don gilbert's Garage

Lucky for me, I have unlimited access to a chassis dyno, and have close to 20 hr of tuning time on it, with every concievable type of cover and filter that has been made, modified, holes drilled in it, everything. No difference, lost hp with the ones with holes, lost hp with a freshly oiled K&N. I now take the stock snorkle, knock the inner mold flash down, sand and polish. Nothing works as well as this factory part.