How much power loss can happen with air filter restriction?

[Spyder]

My current intake setup on a mild 440 with 915 heads has a drop base air cleaner and a 2" filter to make it fit under the flat hood. I put a spacer between the intake and carb last spring as a band aid because of some heat issues I was having and now am pretty sure I've solved.

The engine runs strong, sounds good, feels good, and I believe I've got a pretty good tune setup right now but I think I'm losing a lot of power with the drop base and 2" air filter. I don't think I have enough good weather left before they salt the roads so I probably won't get a chance pull the spacer and go back to a taller 3" filter in and go test it out, but how significant of a power/performance loss could that cause? Seeing how little space there is between the air horn and the air cleaner lid with the 2" filter in there was surprising and makes me think I've just got a restrictor plate in it.

 

[Chryco Psycho]

It is likely restricting flow , low restriction filters other than paper or different types of filter systems may allow more flow

 

[Ricks72Chlgr440]

For a street engine, I doubt you'd lose enough airflow to notice. Drive your car for a few miles to warm it up then come home and temporarily remove the air cleaner and go for that same short drive again. That will tell you what you want to know.

 

[Spyder]

For a street engine, I doubt you'd lose enough airflow to notice. Drive your car for a few miles to warm it up then come home and temporarily remove the air cleaner and go for that same short drive again. That will tell you what you want to know.

I'm going to do that on the next day we have dry roads. I've got a Dragy so I can time my 0-60 or 1/8 mile times (on a closed course, of course) and compare.

 

[MerlinsMopars]

Get a filter with a top plate. Edelbrock has them and it should be enough for the big block. It's amazing how much air they can gulp. I had a foam triangle type once, and that motor sucked the whole thing right thru it. Gone!

 

[Chryco Psycho]

K&N also has filter tops which help a lot

 

[Spyder]

I think I'll wind up having to go with the filter top. Went and filled it up with premium and put fuel stabilizer in it for winterization and pulled the air cleaner off for the drive home. Noticeably more power, though still flat through 2nd gear (which reinforces my other thread about wanting to do heads and a cam as a winter project).

That drop filter base and the lid are REALLY close together when it's on! Dummy me, should have noticed it months ago when I put the 2" in. The foil ball shows how much space there is when the hood is closed. Not sure a filter top will work out with that little space but it's worth a try.

That old Offenhauser intake is coming off soon, already picked up a Holley Street Dominator to replace it with. If my measurements are right, it won't hurt my hood clearance. It looks good all polished up but I don't know that it flows all that great.

 

[MarkLevi]

Could be the perspective of the pic, (and I have no real info on this) but but it almost looks to me that your restriction is more this area than the filter?

 

[Spyder]

Ya, 100% you're right. I've got a Holley SD intake in going to put on this winter, pull the spacer out, and go back to a 3" filter so that gap is more. It's WAY to think for any airflow right now.

I also ordered the filter top lid to increase flow more too.

 

[KlsCuda]

The filter top lid will make a huge difference in airflow