Originally Posted by 82KansasCJ
Running the Holley 390 on my 258 and right now I'm running a small holley air filter that is triangular in shape but I'm not sure how good it really is with the washable filter. Not alot of clearance for a large filter.
Thoughts on how much filter I need and what I might use?
We tested those on the dyno, they are about worthess.
What worked on the dyno,
Assuming a 12" in diameter air filter, you need an inch for about every 100 Cubic Inches of displacment.
You can use a LARGER DIAMETER filter for more surface area when you reduce the height, like those 14" filters Edelbrock & Holley are so fond of,
And you need extra filter above about 5,500 RPM since Reversion is going to be an issue and the turbulance inside the air cleaner.
The WORST thing you can have for a filter is what is shown in the picture you posted!
The second worst thing you can have is a 'Velocity Stack' with a little fiter inside it...
I don't use K&N any more, found dirt tracks inside the carb, and I won't have that.
If you oil a K&N enough it doesn't pass dirt, it's restrictive,
If you let up on the oil, it lets dirt pass,
So I don't use them.