In Reply to: Amen! Every gear head I met said the stock inlet is sufficient for the volume of .... posted by . (The Dude) on April 01, 1999 at 11:22:01
Big difference in my book.
And for Russ, The engine does work to draw in air. If you doubt this, try this simple experiment using a syringe. Pull back on a syringe with the needle installed as fast as you can, then remove the needle allowing a larger opening and pull again. Let me know which was easier. The simple physics are that the vacuum on the piston top that is pulling in intake air is equal in force to that resisting its downward movement. Mother nature hates pressure differences and the easier you can make it for those differences to equalize the more efficiency you will have.
And as for "tuned" intake and exhaust have a look at this web site and the calculators there for inlet length and header length. http://sura1.jlab.org/~grippo/auto_noframe.html
Granted these are simplified versions of the actual calculations but they will get you very much into the ballpark. Notice to get meaningfull results in the streeable range of 3000 to 5000 rpm one would need intake runners of 30" or greater and headers of 87" to 145" long depending on the target rpm. Both of these are a bit difficult to achieve within a stock D and the reason for my previous posts concerning "tuned" exhaust and intakes.
Simple conclusion...Do anything you can to allow for unrestricted flow, intake and exhaust. It is simply the most cost effective means of increasing the performance of your D.
Regards
John