Another Air Intake Scheme

[Bruzilla]

I didn't want to distract from the fresh air 73-74 hood string with this idea, so I'm starting a new string. I have often wondered what the benefit would be of using two fresh air lines running from the high-beam lamp openings to a closed, double-snorkel air cleaner, and installing one of those NASCAR inline brake cooling fans into each hose. The fans have three or four-inch diameters and move anywhere from 150 CFM to 350 CFM.

So, suppose you have two of the 350 CFM fans mounted inline with hoses to a closed air cleaner or air box. You hit the gas, turn on the fans, and have 700 CFM of air flowing in. What would the benefit or negative impact be? Any ideas?

 

[tallhair]

If it's open directly to the front of the car with no obstructions i would imagine that at speed the air pressure would better w/o the fans than with as the fans would probably slow down the airflow due to the restriction .. but I'm just pullin that out of my ***

 

[67 coronet]

i dont think you would get anything out of the fans.as noted by tallhair,i too think they would just impead air flow at speed.many of the old factory drag cars used the snorkle setups with good effect.you normally want that extra air flow at higher rpm,therefore the "ram effect" works well.the fans may do a little at lower eng speeds,but i think it would be negligable at best.nice idea,but hair dryer setups have been tried many times to little or no effect.

 

[rsd859]

I was trying to come up with some duct work that went thru the fender wells and down under the bumper or maybe run it to the middle where the lisence plate goes......

 

[kb67mopar]

The air duct is a good idea the fans are not. They would impede air flow and the laws of energy state that you will gain nothing. The electrical draw from the fan will be required to be replaced by the alternator under engine load and due to losses in the system you will slightly lose power running the fans. Also I have seen dyno tests of similar setups with no gain (actually losses). ( http://www.youtube.com/watch?v=cbGWgvJN1_8 ).

 

[old tired rebel]

Run it like the Lightweight Galaxies and FairLanes.

The Fairlane set up.

 

[69roadr]

if the fans can generate 150 mph wind force, go for it

 

[69roadr]

Run it like the Lightweight Galaxies and FairLanes.

The Fairlane set up.

Damn! love those old Fords too

 

[YY1]

I've never been crazy about the teardrop bump, but I always thought the ram air using the light locations was genius.

 

[Bruzilla]

if the fans can generate 150 mph wind force, go for it

Interesting notion! A 150 MPH wind force is great... except you gotta be driving at 150 MPH to get it. I'm thinking with the fans, there will be a point of diminishing return, but under that point there will be a benefit. If the fans can generate a 60 MPH wind force, then they offer a benefit from between 0 to 59 MPH, which right in the target area for most street driving. Cut the fans at speeds above 60 MPH and you get the best of both worlds.

This needs some more thought.

 

[Photon440]

- - - Updated - - -

Those fans rated at 300 cfm would likely be with no back pressure. Adding back pressure will reduce the cfm. For instance, most fans of that size would be rated to produce about .3 pounds of pressure wide open, and up to .5 with back pressure, but then the cfm would lower.

An open 5" hole at 60 mph will generate 1.3 pounds of boost on it's own, provided you get good smooth ducting (not corrugated dryer tubing) and seal it all really well.

A better benefit would be the cooler air coming in.

 

[old tired rebel]

I've never been crazy about the teardrop bump, but I always thought the ram air using the light locations was genius.

The tear drop scoops were for engine cooling and clearance only not for a ram air effect. Look at the breather hat it is sealed except for the hoses goes.

 

[Bruzilla]

- - - Updated - - -

Those fans rated at 300 cfm would likely be with no back pressure. Adding back pressure will reduce the cfm. For instance, most fans of that size would be rated to produce about .3 pounds of pressure wide open, and up to .5 with back pressure, but then the cfm would lower.

An open 5" hole at 60 mph will generate 1.3 pounds of boost on it's own, provided you get good smooth ducting (not corrugated dryer tubing) and seal it all really well.

A better benefit would be the cooler air coming in.

Excellent point, and that 1.3 lbs of boost would be great if I were driving at 60 MPH, but most of the streets where I do most of my driving have speed limits below that, mainly 45 MPH. As a very wise old cruiser once told me, "I don't break the speed limit, but I get up to it very, very, quickly". Keeping that in mind, I'm not really interested in doing much high-speed driving as that tends to land people in jail, so what I'm interested in is performance gains while driving between 0-50 MPH.

Do you know if there is a set formula for calculating boost according to vehicle speed? That would be very useful. Also, isn't backpressure going to change with engine RPM? A low-RPM engine would create more backpressure because less air is being consumed, but as air demand increases, the backpressure would decrease to a point where it would be zero wouldn't it?

 

[Photon440]

Excellent point, and that 1.3 lbs of boost would be great if I were driving at 60 MPH, but most of the streets where I do most of my driving have speed limits below that, mainly 45 MPH. As a very wise old cruiser once told me, "I don't break the speed limit, but I get up to it very, very, quickly". Keeping that in mind, I'm not really interested in doing much high-speed driving as that tends to land people in jail, so what I'm interested in is performance gains while driving between 0-50 MPH.

Do you know if there is a set formula for calculating boost according to vehicle speed? That would be very useful. Also, isn't backpressure going to change with engine RPM? A low-RPM engine would create more backpressure because less air is being consumed, but as air demand increases, the backpressure would decrease to a point where it would be zero wouldn't it?

Back pressure will decrease as air demand increases. But throttle position will also play the major part. A vacuum gauge will show very little manifold pressure even at low revs when you boot it.

Sorry Bruzilla, I actually found online a set of formulas that took area and speed to calculate pressure when I came up with the above figures, but I didn't bookmark any of them.

-=Photon440=-

 

[kb67mopar]

Back pressure will decrease as air demand increases. But throttle position will also play the major part. A vacuum gauge will show very little manifold pressure even at low revs when you boot it.

Sorry Bruzilla, I actually found online a set of formulas that took area and speed to calculate pressure when I came up with the above figures, but I didn't bookmark any of them. -=Photon440=-

It is unrealistic to calculate a "boost" from driving at speed without taking into account geometry and restriction. Corrugated tubing is terrible for flow and creates turbulence in the ducting which reduces flow and velocity (and in turn pressure), a smooth pipe with smooth bends will provide bigger gains but to create a blanket statement thinking that you will see 1.3 psi at 60 mph is a farse. You may see that at the opening to the duct but it will not translate to the same number at the carb.

It would be best to use a vacuum/boost gauge, create your setup and test. But the bigger the mouth and the faster the speed the higher the pressure and larger the flow rate.