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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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  #91 (permalink)  
Old 05-13-2009, 11:43 AM
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Quote:
Originally Posted by ap72
That's not a bad start, but you would ned to measure not only drag, but also lift- and you don't need to use strain gauges on straps, measuring drag in a wind tunnel is what the wind tunnel is primarily designed for. Also the air speed would need to match the viehicle speed.

Or you could just run pitot tubes in a car that you put on the road right before the throttle plate to measure any change in pressure. (a lot cheaper method).

And Deez, there was no change on a dyno because ram air does not work on a stationary viehicle. (unless you simulate wind as in the tunnel example)

Hey AP want to know how they often measure drag in a wind tunnel. STRAIN GUAGES ON THE HOLDING DEVICE! (albiet different then just straps on a car, but same theory)

If you use several strain guages on the holding device and a little math you can fingure out where the forces are in all directions.

Then again what would I know, I was only taught about it in school, by an instructor who was an engineer on the Harrier Jump Jet in the UK when it was considered "secret". Then again what would he know its not like they would have used a wind tunnell to test this design. (/sarcasm)

Once again read this ------> http://www.streettostrip.com/index2....do_pdf=1&id=64

Some key quotes

"At 150 mph the density increase is 2.75% (2.06% adjusted) which is probably
helpful in some way but is still in the "nearly impossible to measure" category."

"At 350 mph the increase in density is in the 15% range and this is where Ram Air becomes usable"


Then again I don't know why any of us bother to listen to your dribble. You won't listen when you are wrong and that is ALOT of times on here.

I'm actually embarassed for you that you think everything you say is right despite having nothing but "books" for experiance.

Try listening and learning for a change. You don't know it all you don't even know half of it, hell you don't even know 1% of it.

There are some very knowledgable guys on here and i'd say they know 10% of what there is to know put together.

Hell what I know is only 0.00001% of it and I'm not ashamed to admit when I am wrong and learn from it. (You should try it, people are actually willing to TEACH you without getting frustrated)
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  #92 (permalink)  
Old 05-13-2009, 12:47 PM
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Quote:
Originally Posted by ap72
I think its more like pissin on your shoe.

The coefficent of expansion does not change for the air in the circumstances you're talking about, meaning it does not "expand more." If the pressure is held constant then the gas expands linearly proportional to the difference in temperature (atleast as far as this case is concerned).

The oxygen % content is the same in the incoming air charge regardless of if it is heated or not.

After 8 years of engineering school you're going to have to try a lot harder and start using complete facts rather than hearsay if you want to make a sound argument with me.
oh really? 8 years of engineering school at 23? huh. youve been in engineering school since you were 15? i find that extrememly hard to believe. you dont know how to admit that your wrong. your just full of yourself. so keep talking and maybe someday you will say something intelligent. i know its a stretch. ***************.

chevy thunder- i agree with you 100%

Last edited by powerrodsmike; 05-14-2009 at 12:07 PM. Reason: Profanity. Please see: general board guidelines.
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  #93 (permalink)  
Old 05-13-2009, 02:25 PM
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The statement of the same oxygen whether heated or not is false ,well probably same percent per lb of air but the colder air is the denser it is, it weighs more per cubic foot therefore passing say 750 cfm of air at 100 degrees,compared to 750 cfm at 50 degrees the 50 degree air will contain more oxygen per cubic foot.As an example take a carbed car tuned for sea level to Denver, retune it for there and compare power output at both places I guarantee it will make less power in Denver.Same principle colder air is denser.
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  #94 (permalink)  
Old 05-13-2009, 02:46 PM
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Can we please reconsider the tornado? LOL

If you had big ol' air horns you could hook them up to some hoses and solenoids and other various contraptions then use a water/alcohol injection when you reach speed. It would be like the sound coming out in reverse, so if they were 133db normal, they would turn into -133db Reverse Amplitude Magnification Actually In Reverse. Each!!!
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  #95 (permalink)  
Old 05-13-2009, 07:07 PM
How fast is fast enough?
 
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Quote:
Originally Posted by barnym17
The statement of the same oxygen whether heated or not is false ,well probably same percent per lb of air but the colder air is the denser it is, it weighs more per cubic foot therefore passing say 750 cfm of air at 100 degrees,compared to 750 cfm at 50 degrees the 50 degree air will contain more oxygen per cubic foot.As an example take a carbed car tuned for sea level to Denver, retune it for there and compare power output at both places I guarantee it will make less power in Denver.Same principle colder air is denser.
You hit it on the head twice in there.

And yes, for those that care I have been in college since I was 16 (I'll be 24 in a month). Eight total years. way too many credit hours (I believe its around 250-ish).

And lastly there are many more knowledgeable people than me on this subject, many who think that debating its validity is pointless. Anyone who can sit down and draw it out can see that it is very real. I don't understand how people can so easily understand the concept of drag but not of ram air, most of it is based on the same principals.

Its really not worth the time to argue it anymore, I request that this thread be closed.
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  #96 (permalink)  
Old 05-13-2009, 07:11 PM
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Quote:
Originally Posted by ap72
And yes, for those that care I have been in college since I was 16
!!!

Quote:
Its really not worth the time to argue it anymore, I request that this thread be closed.
LOL!!

That's WEAK!
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  #97 (permalink)  
Old 05-13-2009, 07:17 PM
How fast is fast enough?
 
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Originally Posted by cobalt327
!!!

LOL!!

That's WEAK!
What would you have me say? I could recomend some good reference and text books but I know people will not take the money or the time to get it. I really can't understand why this stuff is so hard to understand for some people. But then again somethings are hard for me to understand which come so easy to others- like a proper butterfly stroke.
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  #98 (permalink)  
Old 05-13-2009, 07:26 PM
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Quote:
Originally Posted by ap72
What would you have me say?
Well, it wouldn't be to ask for a thread to be closed- that you didn't even start- that's for sure.

If you're weary of defending your position- bow out. Don't plan on quitting the game, then taking someone else's ball and go home w/it, though.
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  #99 (permalink)  
Old 05-13-2009, 09:40 PM
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Originally Posted by ap72
So your justification is a wiki article? wiki si a great place to get ideas of where to start real research but I would hardly say its the final judgement.

Uhh... you're the one who posted the link to the wiki in favor of YOUR argument.

So its in your favor when its on your side, but when we cite it as part of our argument, its not credible?

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  #100 (permalink)  
Old 05-13-2009, 09:47 PM
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Quote:
Originally Posted by cobalt327
!!!

LOL!!

That's WEAK!
Amen, brother. I'm 35 with a few engineering credits under my belt, including working as an engineer for Volvo, GM, Ford, and briefly Honda.

This guy's no Jedi. He will learn the ways of the Forum Force, but for now he's just relying on internet anonymity and a big soapbox.
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  #101 (permalink)  
Old 05-13-2009, 10:05 PM
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Quote:
Originally Posted by ap72
You hit it on the head twice in there.

And yes, for those that care I have been in college since I was 16 (I'll be 24 in a month). Eight total years. way too many credit hours (I believe its around 250-ish).

And lastly there are many more knowledgeable people than me on this subject, many who think that debating its validity is pointless. Anyone who can sit down and draw it out can see that it is very real. I don't understand how people can so easily understand the concept of drag but not of ram air, most of it is based on the same principals.

Its really not worth the time to argue it anymore, I request that this thread be closed.

AP it is YOU who does not understand. EVERYONE here except you agrees that at high enough speeds the increase in pressure from ram air WILL help. HOWEVER it will NOT create enough power to overcome the drag created by it. The biggest benifit of ram air on a car is the COLD air you bring in.

As the article I posted suggests (FOR THE 3rd time READ THE THING) ram air is completely worthless below 300 and some MPH.


What have you been in school for since you were 16 ap?

I can almost garuntee unless you are the dougi howser of engineering it wasn't for engineering.

So tell us what has the almighty AP taken in school?
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  #102 (permalink)  
Old 05-13-2009, 10:52 PM
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So tell us what has the almighty AP taken in school?
The answer my friend, is blowin' in the wind...





...tunnel
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  #103 (permalink)  
Old 05-14-2009, 06:17 AM
How fast is fast enough?
 
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Originally Posted by curtis73
Uhh... you're the one who posted the link to the wiki in favor of YOUR argument.

So its in your favor when its on your side, but when we cite it as part of our argument, its not credible?


I posted it not as credit to my argument but for the pretty pictures included. People like pictures.
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  #104 (permalink)  
Old 05-14-2009, 06:30 AM
How fast is fast enough?
 
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Originally Posted by ChevyThunder
AP it is YOU who does not understand. EVERYONE here except you agrees that at high enough speeds the increase in pressure from ram air WILL help. HOWEVER it will NOT create enough power to overcome the drag created by it. The biggest benifit of ram air on a car is the COLD air you bring in.

As the article I posted suggests (FOR THE 3rd time READ THE THING) ram air is completely worthless below 300 and some MPH.


What have you been in school for since you were 16 ap?

I can almost garuntee unless you are the dougi howser of engineering it wasn't for engineering.

So tell us what has the almighty AP taken in school?
Doogie had his doctorate at 14- I'm not that good.
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  #105 (permalink)  
Old 05-14-2009, 06:53 AM
How fast is fast enough?
 
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Here is the easiest way of sowing the effects of ram air do not increase drag. It is admitidly primitive but also easily understood.

take a large box and swing in through the air.
Now cut a whole in the face of the box and swing it through the air.
No extra drag has been created but the pressure at the face of the box has passed through it, in fact reducing drag.
Now cover it back up, this is what the car would experience in motion with the engine off (no air passing through the hole).
With the car at WOT then the pressure felt would be much less (as flow through the hole in the box goes up then the pressure exerted on its face goes down).

Now here's the trick that I think most of you don't understand (I take for granted you can understand the above example). The pressure at the throttle plate at WOT does NOT have to be positive for ram air to have an effect, it just has to be MORE positive than without it. If you have a restricted ram air system that cannot flow enough air (as flow demand goes up pressure goes down) the intake may in fact still see a vacuum while the car is in motion, but if that exact same intake ducting is used and there is a greater vacuum while the car is stationary then in fact air is being rammed into the intake when the car is in motion, even though there is still a vacuum on it.

Now the trick comes in where you have to design an intake system that flows enough without creating additional drag from modifying the lines of the car (or even reducing drag or lift) that you will actaully see a slight positive pressure (the advantage of ram air) rather than simply a reduction of vacuum before the throttle plate (which many cold air "systems" can produce). In order to maximize the positive pressure gained from the ram air system it needs to flow the most with the least amount of pressure decrease from the front of the car to the throttle plate, which means bigger is better provided you don't increase drag in the process (which can be done as noted in the example above)

Cowl induction is another type of ram air system that uses air from a high pressure area of the car to feed the intake, but because the opening is reversed from the more traditional appraoch people often seperate the two.

I'm realy trying to boil it down to the basics here in hopes that people will begin to understand it.
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