Quote: our track unfortunately has some stones lifting off the seal on the return road & after seeing 1 racer get a stone flick up from their front wheel & lodge itself into carbs butterflies, i would never ever run without some kind of filtration on my carb. the car with the stone in the butterflies took off with front brakes locked on & plowed into another racecar before the owner could shut it off. not a happy day for 2 racers that day. i'm using Frams Airhogg air cleaner. it's pretty good, virtualy no difference with it on or off, but i now leave it on.
and if you are going to use a "conventional" round style air filter, get one with a breathable top. Just that much more area that is seldom used.
I found the top lid causes issues on flow... you get 2 different air paths that crash into each other and in the end you get less into the carb... I also see that its worse if you have a drop base because the air is going up first then has to turn down to get into the carb.. but the side air is plowing into the lid air ... on the track I dont run a air cleaner
All I can add to this discussion is from my own on-track testing some years ago. I was using a 14" Moroso drop-base housing w/ a K&N 14" x 3" filter and the carb was dialed in for best MPH under the conditions. I swapped to a K&N X-Stream lid and back-to-back testing the car picked up .4-.5 MPH over the standard Moroso lid.
I have limited hood clearance and this was the only way to add filter area I could work out at the time. Although I've heard more than one person p!ss on the X-Stream lid, on my car it helped.
Helped on mine also. I have some issues with it disrupting air flow in to the carb, especially since it covers a lot more area than the inlet area of the carb it is sitting on. If there is an air flow disruption, I would think a lot depends on the distance of the top to the carb inlet. I still think the more filter area you have, the better.
