View single post by discogodfather
 Posted: 08-24-2020 12:24 am
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discogodfather



Joined: 09-17-2007
Location: San Francisco, California USA
Posts: 221
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 Just a word on the experience I just had building an airbox system out of a pipercross 600 universal airbox: 4" is way better than 3" fpr Lotus 907 engines. I started with a 3" version and quickly abandoned it for the 4" size. I felt as if a 3" hose barely could support 200hp in terms of CFM. Even 4" seems somewhat constricted, especially when using a cone filter in the front of it that is sealed into a cold air intake.

It might be a good idea if you do a copy to do what most manufacturers do when they have a group that wants either 3" or 4" (like NACA ducts or brake cooling ducts) is to include a step that can support 3" or 4". If you want 4" you just cut away the 3" and a small taper comes to a 4" ledge.

Just a thought, if you wanted to sell this to more people looking for more flow. The Lotus airbox design has a ton of volume so it masks a lot of high rpm flow problems by simply having a lot of air in reserve.