2.7l cis question

[goldsc78258]

I have a 1977 911s that I just finished and want to race it in autocross and drivers ed I was thinking of making some 1" holes on the air filter cover somebody said it helps the engine breathe is this right? or is this a useless modificationand waste of time?

[911nut]

Don't bother.
I went as far as to eliminate the airbox cover altogether, for a short time. I fabricated a frame that held the air filter in place. The butt dyno revealed no change in breathing and, as a result, power (and I got flamed by the "experts" here on the board pretty bad too, but that's another story).
The best thing that you could do is to rig yourself a cold air intake. I made one from a leftover heater tube, tie wraps and some caulking. A cold air intake will make the power developed by the engine more consistent.

[jluetjen]

The Air meter is what limits CIS intake systems -- not the air-box. Unless you can think of a way to get more air though the air meter (without messing up the mixture), fiddling with other things is not going to make a difference.

Have you replaced the heat exchangers for early style exchangers of SSI's? That will make a difference.

[goldsc78258]

Thanks I have replaced the heat exchangers. It didn't make much sense to me the drilling of the holes the other idea from the first post is better
Thanks again