Some air filter figuring.

[Detroit Bill]

I posted this link elsewhere but I thought this was interesting so I am sharing some observations.

Second Strike Air Cleaner Calculator

A few observations from playing with the calculator. Oiled felt flows much better than paper or foam. A K&N 9" filter with X Stream top can flow enough air for a High HP big block. And that filter fits in a Turkey pan.

I don't have my car yet so it is all academic to me but the Turkey pan acts as a cool air intake (in theory) and heat shield for the carb which makes it desirable from a technical standpoint.

Acton sells this filter.
MAXX Air System MAXX Air System [427 289 CSX CCX KMP ACE HT SPF] - $267.40 : Acton Custom Enterprises, Custom Metal for Cobras

The only difference's I can see from this to a stock K&N unit is the base is flat no rise like the K&N and there is a button that replaces the nut both of which saves some space. It is pricey but you should not have to replace the elements and they sell different heights of filter. Patrick modified a base to drop it and if you went that path you can save around $100.

By my calculation the top when the rim and center is taken into account is 24.28 square inches for a 9" filter and the 2-1/2" filter is 49 Square inched for a total of 73 square inches. That amounts to a 2 hp loss for a 600 hp, 482CI at 6,000 RPM (my targets).

A 14" x 3" oiled felt filter would amount to a 1 hp loss with the same engine. The Turkey pan has some HP value perhaps which could be argued.

There is the question of the look of the filter, I did not like it at first but it is growing on me. I guess you could have a show and go filter.

My engine is being built. If I could get some clearance information from someone with a Superformance and an FE Blue thunder dual plane intake I
could buy the filter without the car. With that I could run the filter on the dyno when it is time to see the performance change. Could be interesting.

[cycleguy55]

I'm pleased to see the 9" x 2.5" and X-Stream combo is good for minimal loss on your 600 HP engine, as that's the combo I'm planning for mine and I'm nowhere close to that power level.

One aspect not covered in the calculator or your comments is that of airflow direction. Clearly an X-Stream top will allow airflow down into the carburetor in addition to the air flowing in through the sides of the 9" element. The 14" x 3" element, OTOH, passes air through the element and it then needs to flow horizontally before making a turn into the carburetor. I did see a post elsewhere that indicated Chevrolet L-88 drop bases are very good (Experience with Edelbrock air filter), but clearly different drop bases could have an affect on power depending upon how they are shaped and how good the airflow is into the carburetor.

None of this probably makes any difference when the engine is running even under a moderate load, but I could see how it might affect an engine running under WOT, particularly if the carburetor has a choke, as the space between the top plate of the 14" x 4" air cleaner and the choke horn could restrict the airflow.

All this is purely theoretical, and I'm curious as to whether anyone has studied or compared the above.

[Detroit Bill]

Originally Posted by cycleguy55

I'm pleased to see the 9" x 2.5" and X-Stream combo is good for minimal loss on your 600 HP engine, as that's the combo I'm planning for mine and I'm nowhere close to that power level.

One aspect not covered in the calculator or your comments is that of airflow direction. Clearly an X-Stream top will allow airflow down into the carburetor in addition to the air flowing in through the sides of the 9" element. The 14" x 3" element, OTOH, passes air through the element and it then needs to flow horizontally before making a turn into the carburetor. I did see a post elsewhere that indicated Chevrolet L-88 drop bases are very good (Experience with Edelbrock air filter), but clearly different drop bases could have an affect on power depending upon how they are shaped and how good the airflow is into the carburetor.

None of this probably makes any difference when the engine is running even under a moderate load, but I could see how it might affect an engine running under WOT, particularly if the carburetor has a choke, as the space between the top plate of the 14" x 4" air cleaner and the choke horn could restrict the airflow.

All this is purely theoretical, and I'm curious as to whether anyone has studied or compared the above.

I saw that post.
There is benefit in theory to the flow coming straight down but who knows.
One of the best air intake scenarios is the velocity stack anything but that the air has to curve and there is turbulence.

As far as I could tell to do a drop base you need a 14" filter and I don't see many photos of a Cobra with a stock hood and a 14" filter. Maybe someone will chime in a point out some examples but I think it is a tough fit on many cars.

[cycleguy55]

Originally Posted by Detroit Bill

I saw that post.
There is benefit in theory to the flow coming straight down but who knows.
One of the best air intake scenarios is the velocity stack anything but that the air has to curve and there is turbulence.

As far as I could tell to do a drop base you need a 14" filter and I don't see many photos of a Cobra with a stock hood and a 14" filter. Maybe someone will chime in a point out some examples but I think it is a tough fit on many cars.

I have a 14" air cleaner with a drop base, but it's sitting in a box as the hood won't close with it on. I'm going to a system similar to the MAXX Air System MAXX Air System [427 289 CSX CCX KMP ACE HT SPF] - $267.40 : Acton Custom Enterprises, Custom Metal for Cobras in hopes the filter will fit up into the hood scoop.

I'm also looking at replacing the 1/2" carburetor spacer with a 5° wedge plate (http://www.summitracing.com/int/part...5030/overview/) to angle my carb and air cleaner down 2°, rather than up 3° as it is now, in hopes that will not only lower the front of the air cleaner but also give better alignment of the air cleaner to the hood scoop.

[Detroit Bill]

Acton also has a 2 piece turkey pan. I think Kirkham is the only other source of a 2 piece.
They are also pricey.

Why the 1/2" spacer?

[cycleguy55]

Originally Posted by Detroit Bill

Why the 1/2" spacer?

It was there when I bought it. It's phenolic, and I believe it was installed to insulate the carb and let it run a bit cooler - but that's pure speculation on my part.

[Morris]

The air cleaners we use on the race motors are home made and are 16"x3" air cleaners with a dropped base ..... we shape them like a oval .... the 16"inches allows more air .....

[Morris]

You might notice it's a 4500 Dominator we use and it works quite well especially on the high end....

The top allows us 2"inches of air coming in .... but 16" of space....

[Bobcat]

yes , but you cheated by turning your hood scoop around to take advantage of the high pressure in front of the windshield . Also , looks like getting the hood scoop up that high will allow the Extreme top work as it should .
Wish there was a way to do that on a "street " Cobra . Best I could come up with was the L88 drop base .
Anyway , looks great and a neat solution to getting enough air for the Dominator ..

Bob

[Detroit Bill]

Wow that fits under a standard hood? I looked at your gallery. Could I get something fabricated for a 4150 body.

[Detroit Bill]

Originally Posted by Morris

You might notice it's a 4500 Dominator we use and it works quite well especially on the high end....

The top allows us 2"inches of air coming in .... but 16" of space....

I looked at the rest of your gallery. Wow I impressive.

[Morris]

Originally Posted by Bobcat

yes , but you cheated by turning your hood scoop around to take advantage of the high pressure in front of the windshield

Our windshield is only 6"inches tall.......so there's no high pressure area.....it's actually a low pressure area.....

[Bobcat]

Now you really have me curious . I`ve stayed away from the Extreme lids for several reasons ( on my car ) . Clearance , or the lack of clearance between the carb vent tubes and the lid . I`ve always tried to keep a minimum of 3/4" between the lid and vent tube , but may have found a way around that with the side vented tubes from BLP . The other area I was concerned with was the Extreme lid being so close to the scoop/hood that the carb couldn`t pull the air in correctly . In talking to K&N , they said if the lid was too close to the hood , it could create turbulence with the incoming air and effect metering on the HSAB and IAB . I was told that their tests were done " in the open " .
Looks like that isn`t an issue with your setup .

[Gaz64]

Looking for comments on these type of filter:

11" Air Filter Components

[Morris]

Originally Posted by Bobcat

Now you really have me curious . I`ve stayed away from the Extreme lids for several reasons ( on my car ) . Clearance , or the lack of clearance between the carb vent tubes and the lid . I`ve always tried to keep a minimum of 3/4" between the lid and vent tube , but may have found a way around that with the side vented tubes from BLP . The other area I was concerned with was the Extreme lid being so close to the scoop/hood that the carb couldn`t pull the air in correctly . In talking to K&N , they said if the lid was too close to the hood , it could create turbulence with the incoming air and effect metering on the HSAB and IAB . I was told that their tests were done " in the open " .
Looks like that isn`t an issue with your setup .

Bob

It's not an issue with us and somewhere I have a photo of how close the hood scoop is to the top of the air filter .... but I couldn't find it.... I'll post it if I find it....

[mikeinatlanta]

Those calculators are pretty much worthless unless you know the actual flow numbers for the particular media you are using, and the actual square inches of media in the filter of a given size.

For me: 14X5, no problem with a few minor hood mods.

[Detroit Bill]

Originally Posted by mikeinatlanta

Those calculators are pretty much worthless unless you know the actual flow numbers for the particular media you are using, and the actual square inches of media in the filter of a given size.

For me: 14X5, no problem with a few minor hood mods.

Cool I'd like to see whats under the hood.

[mikeinatlanta]

four hundred and thirty two inches of eight thousand rpm revving aluminum small block badness. The only, and I mean ONLY even remotely OE part on the motor is the timing cover.

[Detroit Bill]

MJB Engineering - Performance is our Specialty

This is beyond pricey but it does give a large filter area in a small package.
It has some drop. I could not contact the manufacturer because it is Saturday so I don't know the exact dimensions but it looks like they trimmed the outer ring off a 9" Xstream KN lid(s).

I have the two tops at 29 square inches each and a 2" tall oval filter at 59 square in inches for a total of 117 square inches. That is almost like mounting a 3.6" tall oval filter? That seems wrong but I think the math is good.

That is a .65 hp loss on my engines targets of 600hp, 6000 rpm, 482 cubic inches based on the second strike calculator. Not so worried about the hp loss (it appears I will have plenty) as the engines ability to breath fully.