Air flow
 

I am trying to decide what would be a better benefit . Getting my new M.demon carb in a couple weeks for my 427so w/mild cam. It has the 8"x2 3/8 stellings on there now. MY options are
1)going to a 10x3 1/2 w/no spacer.
2)keep the 8" stelling and use a 3" fillter w/a 1" spacer
3)go to a 9" x3" filter and use the 1" spacer
I guess what i am trying to ask is a spacer going to help the car more or is a bigger air filter. I was told that 6cfm per sq. in. on a k&n ? I wanna keep it fairly orig. lookin...Thanks

Back up ttt...

Sparks


we recentlydynoed a 427 fe =.030 and 4.250 stroke---after runnig the setup several pulls with just a K&N 14 in baseplate we put on a 14*3 with an 14 extreme top and didn't lose any noticeble performance. without the air cleaner base on the carb the differance was horrible. so if you must have original luck with small base air cleaners be prepared to give up a lot of performance.

i used a 14" x 4", could go to a 3", but it is a drop base and stays above the fuel rails.

i'm a form follows function type of guy though.

now i just have to find a scoop to go over the top and get the damn thing running correctly.

If I was a serious racer I would prob. do the same...

Air Flow
 

We did an actual dyno test on my KC alloy 373, using a universal spinners 1.5 dropped base and K&N E-3728R 2 ply un-oiled air filter 14" x 3.5", this air filter setup has approx 1-1/8" gap for the air to flow around the nice base which works real well, because, we did a side by side dyno run with no air filter and it made NO difference. My carb is a Pro-systems and right through our testing the operator who does a lot of F5000 Injected engines commented on the manners of my engine, we also found that a 1/2" carb spacer gave us 10bhp at the top end. Keith Craft did a real good job.

What the carb spacer does is allow the air flow to turn by giving more room after it leaves the carb, before it hits the manifold floor. Also I think a well designed filter base is important as it gives an area for the air to transition over, and as mentioned these smaller type air cleaners used on the FE 427 engines are only a compromise because of lack of room, but I guess work okay for road use!

that's interesting ant.

in addition here's something from david vizard, how to build hp

air filters flow more when the diameter is relatively large by comparison with their height. the dia. of an element should be four to five times the height. the lid of the filter should never be closer than three inches to the carb mouth or choke horn.

no more than 1.5" of water pressure drop across the air filter element at full throttle, max power rpm, is acceptable.

prob pretty general.

Thanks for the input. Gonna go w/a 9x3 " k&n. Filter bottom has a 1/2" rise and room for a 1" spacer under carb.

Well I ended up useing a 1/2 carb spacer,9x3" k&n filter, a mr gasket chrome air cleaner ( looks pretty close to a stellings)w/a 3/4" rise on the base and a mighty demon 825cfm. What a BIG differance from the old set up. Much more responsive, seems to have alot more low end trq...Even starts better. Time to toss that old vacum holley.:D

good deal, always nice to see improvements. beats the alternative.:)

We also have done some dyno runs with various filters. There was some lower numbers with the S/H being so small (I like the look) but, the worst was the dropped base. You're cutting cfm into the carb. because apx. half of filter is blocked. It also ran a little,.....lean on fuel, would it be enough to cause problems, I don't know, more intense studies would be needed. I would suggest going with a 12" and not a 14" if room is a problem.

Also, if you're using a K & N type filter, keep it very clean and oiled. We've seen limitations in cfm passing through the filter. I had to increase one pill size because the engine ran lean. They are a great filter if used properly and kept clean. I think people tend to ignore regular maintenance because they are supposed to last 1,000,000 miles. After all, if the filter is plugged up, no air gets through. We ran a car that the owner failed to keep his oiled filter clean, then used a cheap paper filter, the results were amazing for just a filter. He gained 4 hp. That to me proves that mama was right, everything works better,......clean. ;)

On the sprint car, we use the K & N that has one filter per 2 cylinders, so four all together. We now clean them every week, rather than what most sprint teams schedule is, of one time every 4 races. We have not hurt a engine in the last 8 years due to lack of maintenance, and that's the key !
So, keep your filters clean guys.

i've had experience with k&n passing dirt through the element. i'm under the big paper plan now.