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View Poll Results: Cold air vs Ram air
Cold Air 17 60.71%
Ram Air 11 39.29%
Voters: 28. You may not vote on this poll

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  #16 (permalink)  
Old 04-17-2009, 10:32 AM
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Quote:
Originally Posted by ap72
And if the air is already benig ducted through the body?...
But what air is that? The only air that should be ducted through the body is for cooling purposes (radiator, brakes, A/C condenser), in which case it's already heated and not something you want to use for a "cold air" inlet. Also, if the airflow has passed through a head exchanger like that, the pressure on the other side of the heat exchanger will be substantially lower due to drag through the exchanger. That pretty much negates any "ram" effect.

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  #17 (permalink)  
Old 04-17-2009, 10:48 AM
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You can see what is an effective system by looking at what is/was being by NASCAR top level cars.

Even before NASCAR mandated how and where air got to the carb, most if not all were using much the same scheme.

A good system for most apps could be called a "cool, still air" intake.

It is more (but not all) about cooler air, than pressurized air, IMHO.

Sometimes, in an attempt to get a "ram-air" effect, all that is accomplished is the carb gets turbulent air that ends up confusing it.
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  #18 (permalink)  
Old 04-17-2009, 11:31 AM
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Quote:
Originally Posted by joe_padavano
But what air is that? The only air that should be ducted through the body is for cooling purposes (radiator, brakes, A/C condenser), in which case it's already heated and not something you want to use for a "cold air" inlet. Also, if the airflow has passed through a head exchanger like that, the pressure on the other side of the heat exchanger will be substantially lower due to drag through the exchanger. That pretty much negates any "ram" effect.

There's air coming through the car all over the place. Look at the front of your car,I'm sure you'll see the holes and gaps. My ram air on my Cutlass is routed thorugh the factory holes in the front bumper, instead of sending air under the car (where you don't want it) it send it through the engine and out the exhaust.
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  #19 (permalink)  
Old 04-17-2009, 01:23 PM
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Quote:
Originally Posted by ap72
There's air coming through the car all over the place. Look at the front of your car,I'm sure you'll see the holes and gaps. My ram air on my Cutlass is routed thorugh the factory holes in the front bumper, instead of sending air under the car (where you don't want it) it send it through the engine and out the exhaust.
And to get back to your prior post...

Quote:
Originally Posted by ap72
"ram air" is not a myth, and if applied corrctly will not increase resistance (it can actaully lower it).
...using these as O.A.I. pickup points will most certainly NOT lower the drag on the car. If you could reliably measure the drag, it would probably show a minor increase. If you're talking about the 1966 Olds W-30 setup, the air flowed completely through the slots in the bumper. The O.A.I. scoops not only increased the drag, but moving the parking lights inboard to make room for the scoops further increased drag by making the opening in the bumper smaller. Given how non-aerodynamic the 1960s and 70s cars were, however, this is probably a moot point.
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  #20 (permalink)  
Old 04-17-2009, 01:55 PM
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Its on a '72 and is not factory. It was mostly fabbed by my pop who has done a lot of sheetmetal work. Nothing was changed on the cars exterior when this was installed, not even a bulb. And while I still contend that it reduces drag (even though its only ever so slightly) and that it pushes air through the carb, although again only slightly, it has no real draw back other than the increased weight from the added sheetmetal. There is no advantage that a "cold air" intake would have over a setup such as this.

I in no way am trying to say this will add 100hp, but its advantages are nonetheless real albeit slight.
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  #21 (permalink)  
Old 04-18-2009, 11:03 AM
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Quote:
Originally Posted by ap72
I in no way am trying to say this will add 100hp, but its advantages are nonetheless real albeit slight.
what I'm saying is that there is no free lunch. This is another conservation of energy debate. Let's say by some magic of the universe you are actually getting a measurable increase in pressure. In order for that to happen, the drag imposed by the ram has to be greater than the increase in pressure. Its physically impossible for it to be not.

The same could be said about attaching a windmill to your car to generate electricity to power the wheels. The drag would be far greater than the electricity produced and the net energy gain is negative.

Ram Air is a myth. If it generates positive pressure, it is generating more drag than it is power. Period. Any benefits you have from ram air are because you're getting cold air.

Not to mention, if you were getting effective increases in pressure at the ducting, your carb would have to be retuned to accomodate the pressure. Adding positive pressure to a carb messes it up without a lot of modification.
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  #22 (permalink)  
Old 04-18-2009, 12:15 PM
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Quote:
Originally Posted by curtis73
what I'm saying is that there is no free lunch. This is another conservation of energy debate. Let's say by some magic of the universe you are actually getting a measurable increase in pressure. In order for that to happen, the drag imposed by the ram has to be greater than the increase in pressure. Its physically impossible for it to be not.

The same could be said about attaching a windmill to your car to generate electricity to power the wheels. The drag would be far greater than the electricity produced and the net energy gain is negative.

Ram Air is a myth. If it generates positive pressure, it is generating more drag than it is power. Period. Any benefits you have from ram air are because you're getting cold air.

Not to mention, if you were getting effective increases in pressure at the ducting, your carb would have to be retuned to accomodate the pressure. Adding positive pressure to a carb messes it up without a lot of modification.
I agree that carb tuning is a PITA and really can't be perfect for all driving conditions since the slight increase in pressure is speed dependant. HOWEVER you're making one huge and common faulty assumption- and that is that adding a system increases total drag. That is not necessarily true. It is true in most cases, but not all, and the difference can be made up through good engineering on the track or the streets.

I'm not saying everyone needs one nor that everyone can do a good job of building one, just that it is done. If it wasn't at all possible then you wouldn't see them on the tracks.
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  #23 (permalink)  
Old 04-18-2009, 12:36 PM
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I don't think you are understanding AP.

What everyone here is trying to tell you... even if say you put your ram air in place of your radiator. Air would typically flow through that area at a greater rate then the engine is drawing it in.

Even if you replace any solid part of your car with ducting. Air would normally flow over that area more efficiantly, the ducting now creates negative flow characteristics.

I did testing on a 40 ft wide duct in CFD software. Essentially it was a big cone with air coming in the big end.

@ 50MPH hitting the front of the cone, do you know what kinda pressure increase there at the highest point over a 40 ft area?

like 0.3 PSI

and the air that was supposed to be coming into this cone saw this slightly higher pressure and tended to want to go around it.

The results were really disappointing to the person who designed it.


I know this isnt the same exact thing but if you look at the results of that and use critical thinking you should understand what the point is.

And if you think 0.3 PSI is a mesureable gain of pressure @ 50MPH with a 40 ft wide cone that tapers down to 20 ft, you won't understand what is being said here. Ever
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  #24 (permalink)  
Old 04-18-2009, 04:43 PM
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Quote:
Originally Posted by ap72
HOWEVER you're making one huge and common faulty assumption- and that is that adding a system increases total drag. That is not necessarily true. It is true in most cases, but not all, and the difference can be made up through good engineering on the track or the streets.
You're missing the physics facts. Go back and look at what Joe said on page one. In order for there to be pressure, there has to be drag. Period. If you have a 4" duct behind the grille picking up air, it won't make much drag, but it also makes no pressure. If you want pressure, you'd have to have a 12" bell collecting air, at which point you WOULD have tons of drag, and it would still only make an almost unmeasurable pressure increase. There is no crossover point, there is no engineering that can make it happen. The drag will always be greater than the power you get out of it.

This is like the water-fueled car. People keep saying that we just need to make it more efficient, but that isn't the case. I don't care how big, small, or well-engineered it is, it will not create pressure without drag. Period.

Not to mention, you need crazy speeds to generate any pressure... like 150 mph+. On the street there is absolutely no benefit to ram air over cold air. There physically can't be unless you have violated the first law of physics. Using the forward motion of the car in order to generate energy to add to the motion of the car is perpetual motion. It can't happen. Even if you manage to add 1hp of engine output at highway speeds, the drag involved would take more than 1 more hp, and the system is a net loss.
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Old 04-18-2009, 08:29 PM
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There is also confusion about some of the cold air kits and filters for the newer cars, and its reinforced by ambitious claims from K&N and other companies.

For example, there is a Ford Racing cold air kit for my 2005 Mustang GT, and it adds about 20-25 HP (which has been confirmed by several testers). However, calling it a "cold air kit" is misleading, because it also includes reprogramming the computer, and a mandatory switch to premium fuel. The cold air intake may work to lower air temps, but I think most of the HP improvement comes from the computer reprogramming (which probably advances timing to get the HP).

Bruce
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  #26 (permalink)  
Old 04-24-2009, 08:14 AM
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well.... you guys know more than me and are saying ram air basically is a load of ****. so cold airs got my vote.
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Old 04-24-2009, 08:20 AM
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Originally Posted by 83SILVRADO
well.... you guys know more than me and are saying ram air basically is a load of ****. so cold airs got my vote.

This is the mistake I was affraid of. The best cold air has never beaten a well designed ram air induction, or cowl induction for that matter.
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  #28 (permalink)  
Old 04-24-2009, 08:22 AM
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Quote:
Originally Posted by curtis73
You're missing the physics facts. Go back and look at what Joe said on page one. In order for there to be pressure, there has to be drag. Period. If you have a 4" duct behind the grille picking up air, it won't make much drag, but it also makes no pressure. If you want pressure, you'd have to have a 12" bell collecting air, at which point you WOULD have tons of drag, and it would still only make an almost unmeasurable pressure increase. There is no crossover point, there is no engineering that can make it happen. The drag will always be greater than the power you get out of it.

This is like the water-fueled car. People keep saying that we just need to make it more efficient, but that isn't the case. I don't care how big, small, or well-engineered it is, it will not create pressure without drag. Period.

Not to mention, you need crazy speeds to generate any pressure... like 150 mph+. On the street there is absolutely no benefit to ram air over cold air. There physically can't be unless you have violated the first law of physics. Using the forward motion of the car in order to generate energy to add to the motion of the car is perpetual motion. It can't happen. Even if you manage to add 1hp of engine output at highway speeds, the drag involved would take more than 1 more hp, and the system is a net loss.
pressure is created at 1MPH (albeit only a slight amount), and pulling air from a high pressure area does not necessarily increase drag. And this in no way violates any laws of physics.
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  #29 (permalink)  
Old 04-24-2009, 11:23 AM
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If you look at how the NASCAR cup cars do it, that's as efficient as you're gonna get- IMO.

Newton's laws of motion, et al- seem to negate any free lunches, as it were. But I'm SAH no physicist, either.
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Old 04-24-2009, 11:38 AM
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Quote:
Originally Posted by cobalt327
If you look at how the NASCAR cup cars do it, that's as efficient as you're gonna get- IMO.

Newton's laws of motion, et al- seem to negate any free lunches, as it were. But I'm SAH no physicist, either.
A lot fo racing rules, NASCAR included, ban things like ram air...
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