I have seen some people have modified their stock airbox as suggested on rob robinette’s site, but without ducting you are making one heck of a hot air box. The problem with just cutting holes in the bottom of the stock airbox is the radiator fans, when activated blow right into your new holes, and right into your intake, so when you stop for a light you intake air goes from 34deg C to 98deg C. The ducting is a critical element to keep your intake safe.

This discovery was mad while testing my cold airbox designs; what a difference a piece of aluminum can make..

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To clarify, if one neglects to install the ducting from the box to the side of the rad, as fully specified at the robinette site, then a hot air intake results, as u noted.

The hot air box is a result of not following all of rob's instructions.

 

Yes the MOST important part of the STOCK AIRBOX MOD is the ducting down past the side of the radiator that keeps the hot air out of the intake

Photos of my version of the mod.
https://www.rx7club.com/photo/index....humb=1&cat=500