If you are using one of these type air cleaner bases - stop, and throw it away

This type of air cleaner base is very popular. However, dyno testing with just the base on a Qjet showed a significant loss. With no other changes (10 deg warmer water), adding this base lost 36 hp and 42 ft lb vs no base. The very next pull, in which the only change was removing the base, and on a different day (5 deg warmer air, 10 deg cooler water), picked up 44 hp and 47 ft lb.

Adding a different air cleaner base was much more beneficial. I have one that is older, but is radiused, much like and OEM GM base, with about a 5/8" drop. I'll get a pic later. With the only change being adding the base, it picked up 4 hp and 1 ft lb at peaks over no base, and traded back and forth thru rpm. The relevant part is that there was no huge loss. AFR numbers improved, they were more consistent thru the rpm with this base.

I think that the flat surface and sharp angles of the base in the pic that close to the carb affected the metering somehow.

 

I don't like those bases anyway. I use a stock air cleaner base with a larger than OEM air cleaner so it gets air all around the sides and top. The picture of the air cleaner you showed always seems to hit my throttle linkage.

 

Hanging around to hear more about this one.

 

I have that exact base on my Biscayne. I don't have (and don't want) to use an OEM air cleaner. What other options are there? Thanks for posting this.

 

I run that same low-profile base on my stage one for Hood clearance because of the 1 inch spacer on the intake. I'm definitely going to run the Edelbrock low profile Air cleaner now.

 

I had an engine builder tell me one time to NEVER use a K&N filter. The reason they flow so well is that they don't filter well, according to him.

 

Tom Rix has proven the factory lower base ( or aftermarket equivalent) Corvette and or the 68-69 Z-28 which are the same, when running a 4150 Holley gives the most hp. Pretty sure he said the same for stock class racing using a Qjet.

 

This is from some tests that David Vizard did years ago and should explain a lot !

Besides that type of power robbing base the lid's with filters in them are the other big HP robbers!

 

Thanks for the information, those things are like almost 100 bucks. I'll stick with the Edelbrock little triangle filter.

 

I use this base. Very light aluminum and strong too.
A few years back there was a filter called "The One Piece", I believe. It is made from the same stuff as K&N. I bought one and have been using it since. I don't believe the 455 starves for air. I have it on a quadrajet and it clears everything.

https://www.performancebodies.com/products/prp-air-filter-bases-lids

 

I always heard that the L/88 Corvette base was the best. Is the 68-69 Z-28 base the same?

 

Does a 3"x 14 inch round stock style filter provide no loss for 500-600 hp vs 4x14?
My guess is that 130 square inches is plenty.

 

If your talking about the triangle shaped foam filter Edelbrock sells stay away from those because they do not filter out **** to put it mildly!

I had two of Those in use on the duel quads on my 671 blower and after 25'000 miles the injested dirt chewed up the rotors in my blower, and dirt passing thru the filter will do the same to your piston rings and cylinder walls!!

 

You can keep your top if you like them. Just try to find a base that has the smooth radius which looks like what GM did. Also, the Qjet does not like the vertical wall just above the airhorn.

If you need a drop base, the L88/Z28 one mentioned above is a good one. However, that one is around 2" of drop IIRC. Note the shape and look for something similar in an aftermarket one if you need less drop.

There are spun aluminum ones with in-betwen drop that "look" like they should be ok, they have the smooth radius.

Also the heigth of the air cleaner top has an effect, try not to get the lid too close to the carb

 

Thanks Larry for looking into it the L 88 with this sleight transition is the way to go. Hey if you need to correct cowl screen for your car let me know.

 

Yes, that is the correct L88 base. And that pic of the Chevelle looks the same as the L88 and 68-69 Z-28.
Didn't know that about the Chevelle. Well maybe I did but forgot about that one.
Also, what I did was grind down that inner lip where it sits on the carb. Which in my mind would work better with a modified Holly air horn. Where the choke tower is cut off and the air horn is rounded smooth.

 

Oh, and also grind off that tube on both ends, upper and lower, then plug the hole with a made up sheet metal plug, weld on, grind smooth and done.