Holes in CIS Air Box Covers, Good or Bad?

the_win · 01-09-2003, 10:17 AM

I've seen some pictures of engines with the CIS Air Box Cover having holes punched in them. It looks like a case of real hungry moth's, or they want their cover, to look like Swiss Cheese.

I know that they are doing it to get more air thru the CIS Unit.

But does this really help or hurt? I'm asking because now the air flow is physical different than the orginial design.

Anybody out there a expert in airflow dynamics for this application?

s_wilwerding · s_wilwerding's Garage

Usually the reason people do it is not to get more air flow, but to make the throttle sound "throatier". The disadvantage to doing it is that rain or other water can get in the air intake - that's why the OEM airbox is shaped the way it is. There are some people that only cut holes out of the bottom of the box so they don't have this problem, but if I were you, I'd leave the box stock.

clnilsen · clnilsen's Garage

I think it's been much discussed on this board here, but it bears repeating. The Air box is not the Bottleneck in the engine. You get much more response out of a free flow exhaust since that is where the restriction is.

Good luck!

Chuck

RickM · RickM's Garage

I recall a tuner by the name of BRD doing it to a car that was featured in one of the P Car mags. After that article many got their drill and hole saws out. They mentioned it was used to enhance airflow but weren't more specific than that.

MBAtarga · 01-09-2003, 11:46 AM

Quote:

Originally posted by s_wilwerding
.... There are some people that only cut holes out of the bottom of the box so they don't have this problem, but if I were you, I'd leave the box stock.

Wouldn't holes in the bottom of the box actually bypass any air filtering? Might as well run a K&N filter

speeder · speeder's Garage

I think that he meant the bottom half of the cover of the air cleaner, so no effect on filtering there. This horse has been beaten fairly senseless here before, one look at the surface area of a stock CIS air filter should tell you that it is not a restriction on these motors. I have owned 400+ cubic inch engines w/ smaller areas of filter, and they breathed well.