[Formulajones]

I recently learned a little bit on that subject with our last dyno session a few months back. The shop I used builds roundy round engines mainly so he's used to dirt. I kind of figured he would be a big "cleanable" filter guy, lol.

When I showed up with a brand new 14x4" K&N he immediately said he constantly sees gains on his dyno with a basic paper filter. Perfect, lets try it on this engine. Sure enough it was worth 3 hp with the same size paper filter. Also found out the nice curved bottom GM drop bases are worth a pinch over the cheap blocky looking drop bases that come with basic air cleaners. I guess it helps the air turn.
On top of that the nice rounded curved lids also are worth a little bit. They also have a unique looking shape by the stud, countersinks the wing nut for lack of a better description, that if you look at it from the bottom you can imagine how it helps direct air into the carb. By the time we nit picked air cleaner setups I found almost 10 hp. Of course you see those lids all the time on roundy round engines and he had one handy. I quickly ordered one when we got back home, lol.