Filter Air Flow

[HeavyFuel]

WIX filters available, 1968 dodge charger w/ 440:

#4043 = 3.5 inches high, with snorkel(s), 210 CFM

#4044 = 2.75 inches high, without snorkel(s), 160 CFM


I always thought that '68 440 HP had no snorkel, but there are two filter versions available, according to the filter manufacturers.  ??

Would it be wise to go with the snorkel cover and filter, for better air flow?

Is hood clearance a factor, or can I go with or without snorkel on a stock 440 HP? (are the cleaner covers different heights?)


I think a '68 440 will be totally wrong with a snorkel and I don't think that it was available.

[HeavyFuel]

Got er figured out.....talked to my local mopar expert.......  

Just be aware if you go to NAPA...they have misleading information on the filter for a '68 440 4 barrel...


But I'm still wondering......for instance, if you run a Carter AVS with approx 750 cfm,  doesn't an air filter that only runs 160 cfm just KILL the air flow of the motor?   I thought air filters moved more air than that.

[Budnicks]

Get a K&N or equal gauze type filter element they flow way better, hands down & are cleanable, especially for a silenced type covered air cleaner filter element, it can't hurt, unless of course your in a 100 pt. concourse show... 

[Chryco Psycho]

or if you are running the car in a very dirty environment

[HeavyFuel]

Get a K&N or equal gauze type filter element they flow way better, hands down & are cleanable, especially for a silenced type covered air cleaner filter element, it can't hurt, unless of course your in a 100 pt. concourse show... 

not a 100 pointer.....but going for a stock look.

[Dans 68]

I have dinner plates, in the cupboard, not that clean. Are you related to Bull? 

Seriously, that is nice. 

Dan

[HeavyFuel]

Thanks, Dan.     

Once I get into the re-assy process, I'll start posting progress reports and pics. 

I've pretty much rebuilt, refinished or replaced everything on the car, while trying keep as many factory original (re-use, not NOS) as possible.

[Budnicks]

Get a K&N or equal gauze type filter element they flow way better, hands down & are cleanable, especially for a silenced type covered air cleaner filter element, it can't hurt, unless of course your in a 100 pt. concourse show...  

not a 100 pointer.....but going for a stock look.

That is nice , you could still use the replacement K&N air cleaner element, nobody would be the wiser.... It would still look the same from the outside just flow allot better....

[68X426]

if you run a Carter AVS with approx 750 cfm,  doesn't an air filter that only runs 160 cfm just KILL the air flow of the motor?   

I'm not a mechanical engineer (but I did sleep at a Holiday Inn last night ), so I'll take a shot at this. The cfm measurement is not interchangeable between the two items in question.

The carb "cfm" is a metric that combines air flow in the carb with the motor's compression rate, displacement, rpms, and fuel flow, and is only meaningful when compared as a ratio with the motor's volumetric efficiency. It is relevant when measured wet, meaning air and fuel are mixed. It's not air flow only, and "cfm" is unique to carburetors in this instance.

The filter "cfm" is a metric for air flow only, and dry air at that.

Consider that cfm is used for water flow measurement on rivers and creeks. Not at all comparable to air flow or carb cfm.

CFM is just a number and in this automotive instance they aren't comparable.

I've read that KN filters flow at 400 to 800 cfm depending on size. Clearly a better choice over stock filters. I'll guess that a 750 cfm carb functions at 100% with a KN and loses 10-20% of function with a restrictive filter. Consider though that a poorly tuned motor may lose 40% function, low air in tires loses 20%, and just the shape of a B-body creates drag that decreases efficiency by 30%.

Note that I am making up those numbers to illustrate a point about efficiency - a 750 Carter with a stock filter will work just fine. It won't be killed. There are exactly 57 ways to kill performance, a stock filter is low on the list. And there has to be a measureable difference with a free breathing KN. But the difference may be lost in the mix of all the other in-efficiencies that comprise an internal combustion engine and a B-body Mopar.

Still, within a reasonable budget, we all try to add performance even if it can't be measured exactly. I use KN open top filters because I know they flow better, I just can't measure it.

Please, real engineers, chime in.

[HeavyFuel]

Thanks, x426.....your logic makes perfect sense.  

The '60's engineers surely would have designed air cleaners/filters to work together.  They are both the sizes they need to be, so it makes sense that the cfms can't be compared.