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Old 10-16-2007, 11:41 AM   #21
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I'm not arguing Bill, I'm merely stating that according the article...even with the properly designed scoop/nozzle anything under Mach 5.0 is merely redirection, not ramming. On the continuation sometimes a good debate is healthy. Now according to your last post, it does appear that Alex could see some positive benefits below 120mph and I believe that is all he originally intended to express.
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Old 10-16-2007, 11:46 AM   #22
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I am also a firm believer in the Ram air effect.
I have Ram Air on my Firebird that I fabricated from scratch. It IS a true Ram air setup with a completely sealed air intake and dual under bumper scoops. I have proven it works and gives the engine a performance gain. 1-2 psi at speeds above 80 mph

The scoops are much larger than the ones Alex is using and I believe he will benefit more from the cooling effect than the pressure effect.
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Old 10-16-2007, 11:47 AM   #23
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Quote:
Originally Posted by willwren
Quote:
Originally Posted by BillBoost37
Let'* attempt to keep this on topic for Alex as I was using yours as an example only. However according to the fact that this air doesn't go into a box or intake and it'* under 100mph ...there is no ramming being done. You built pressure by blocking the end of a tube.. and the weakest link allowed the air to escape. There can be airflow w/o ram air.
Funny how you ask to keep it on topic, but continue to argue. This is directly related to the topic being discussed. It is VERY EFFECTIVE ram-air COOLING as I stated above, and was specifically designed to be just that. I don't have to block the end of the tube to build pressure in the delivery tube. It'* 2-3x incoming pressure naturally. There IS ramming being done. I think you're misunderstanding the definition of Ram Air yourself. Even Pontiac'* misrespresented Ram Air designs build pressure and flow. It'* just not sufficient for developing horsepower (can't overcome the natural draw of air in a NA application). I'm not using it for induction.

My scoops are larger than the tube by design.

Posted: Sat Mar 20, 2004 6:24 pm Post subject: Ram air done, complete, tested. Lots of pics (not 56k)

Quote:
Katie and I took the car out to test today (Pooky is in CA at cheerleading nationals). Did 6 runs total. First 3 were with both ducts plugged in the engine bay (outlet ends) with clean rags, and tape to hold them in against any pressure. 3 different speeds (30mph, 45mph, 60mph) recording outside air temp, IAT temp, and SC temp (taken just under the mesh at the top of the SC next to the TB). We taped this thermometer (Fluke) to the windshield so we could see it, and took IAT measurements from the Actron scantool. Ambient air temp was taken from the Climate control.

We then stopped the car to unplug the ducts. Funny, the pressure at the scoops built up to the point that it popped the air hoses off the scoops under the car. This answered the pressure/flow question for me. We got back in and ran the same test at the same speeds, recording the same temps. Keep in mind, this was after full heat saturation of the engine/trans.

Our data:

ducts plugged (no ram air)
Speed----------Air temp-----------IAT temp------------SC temp
30-----------------58--------------------92--------------------93
45-----------------59--------------------95--------------------91.6
60-----------------60--------------------90--------------------81.2

ducts unplugged (ram air flowing)
Speed----------Air temp-----------IAT temp------------SC temp
30-----------------61--------------------86--------------------81
45-----------------61--------------------72--------------------80
60-----------------61--------------------70--------------------70

As you can see, it made quite a difference. I'm basically running both ducts at 10 above ambient temps, with a 10-20 reduction in temps across the board.

We then speed-tested the mounting up to 115mph, with no problems. The sprayed on bedliner coating is tough. Not a chip or ding, but we did have dead bug guts inside the scoops, and a dead wasp in the SC cover mesh
Alex can benefit in the same manner. While the amount of flow and pressure from my scoops isn't sufficient to develop horsepower (if that'* what I intended), it does show there is benefit to using it for cooling instead of induction. In order to develop higher flow and velocity, he can take some of this into his design while selecting downstream components.

This is all very valuable information, not just for Alex, but for anyone else considering something like this.
As you can see from the data above, it works quite well, but let'* stop and think for a minute how effective that would be if I had just the tubes hanging out in the air path?

As effective? No. Why? Natural compression. The area of the scoop is 3x the area of the delivery tube.

I think RAMMING is a very good term for this. Don't you? Again, the article is talking about INDUCTION. The engine'* natual ability to ingest air exceeds what you'd get from a ram air setup.

But if you use it for COOLING, yes, you do get a ram (compression) effect if properly designed, and YES, it is very effective. Much more so than just the tube itself.
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Old 10-16-2007, 11:48 AM   #24
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Ok , so its not "ram air" as per the dictionary meaning. However, it does redirect cold air to where it is needed and its far better than nothing at all so I would call it functional. Besides, its a custom one off that not many people on here have the skill to accomplish. Major props to this guy for doing his thing
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Old 10-16-2007, 11:58 AM   #25
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The hood certainly won't hurt him. That'* for sure. And it'* an attention getter.

In the strictest definition of terms, RamAir induction? Not much there.

RamAir cooling? Yes, it works, it does ram, and it cools. But it doesn't have to keep up with a thirsty motor sucking in air, which is why it works.

I've been using it and testing it for over 3 years on one of my cars, and it makes a dramatic difference at a mere 30mph.
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Old 10-16-2007, 03:17 PM   #26
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Wow. The horse is dead already.

Its a cool looking hood that actually does something.
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Old 10-16-2007, 04:08 PM   #27
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that hood is sweet man. Good work!
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Old 10-16-2007, 04:26 PM   #28
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would a hose on the bottom of that air box be any benefit of fresh air? kind of a fwi and ram air combo? or would they fight against each other?

im bad at even paint let alone p/*, but heres a rough idea
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Old 10-16-2007, 05:57 PM   #29
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He'* going to get nice, cool (relative to the engine compartment), fresh air into his intake...that can't be all bad. Might be worth insulating the intake tube from the filter to the TB in order to keep that air as cool and dense as possible.

In all this banter, you guys are missing the most important point. That being that he can start a calypso party anywhere, anytime. All he has to do is pop the hood, start beating the steel drum under there, and a par-tay will rise out of nowhere.

Alex, you got some cool stuff going on there.
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Old 10-16-2007, 06:43 PM   #30
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Alex,
Your plans look great. You will want to be careful of the number of times you turn corners in your ducting. The more turns you have, the more losses. If you calculate the flow required and the size of the ducting, you can find the average velocity in the duct. If the velocity is small, the corners are less of an issue. This is part of the reason the S2 intake manifold is so tall compared with the S1 (in the NA engines). It is a plenum. A plenum is large to keep the velocities low.

Will and Bill,
The term "Ram Air" in the article referenced in the link is VERY SPECIFIC. Will, what you are doing for cooling is not that kind of ram air. Your cooling has very good pressure recovery but is NOT ram air in the same sense because the velocities are so low (there is no ram air).

What looks like arguing in the preceding posts is all about apples and oranges. You are all really saying the same things. The term "ram air" is not being used the same way though. Pontiac uses "ram air" as a marketing term and the article uses it as an engineering term. This leads to all kinds of confusion.

[edit]:
Anybody can make up a name for anything. For example, I could put scoops on my hood and ducting into the TB and call it "Forced Induction". Then all of a sudden EVERYONE would say "That'* not forced induction". That'* because "Forced Induction" already has a specific and previously agreed upon meaning. So, yes, you can do many things and then measure an improvement (and demonstrate it very credibly), but when you call it "Ram Air" you will get an argument from those that know there is an "already agreed upon meaning" for "Ram Air". Yes, you did something you can measure and demonstrate - BUT IT IS NOT RAM AIR (just like it is NOT "Forced Induction"). It is something else (and this applies to "ram air cooling" as well). We are only quibbling about a name.
[end edit]

In engineering terms, ram air is a product of the DYNAMIC pressure. It doesn't matter what it is used for, whether it be cooling or induction. The dynamic pressure is so minuscule at these velocities, it is basically nonexistent. Even at 100 mph it is still small (0.177 psi or 0.36 in Hg, which equivalent to an altitude change of about 300 feet). There is no way that there is even a few horsepower available.

The referenced article makes a point that fluid dynamics is nonintuitive. The above discussion is rife with examples of this and is full of misunderstandings and misconceptions (by everyone involved). Don't feel as if I'm dissing anyone though, most aerodynamicists that I read or talk to, are confused about some things too. Even the author of the article misapplies mach number and compressibility theory.

I have studied and experimented with various kinds of ducting in aircraft for many years. Most of which has been for the purpose of cooling. Some of it has been for induction however, and as the article states, the benefits are NOT in the area of ram air but in the LOWER DUCTING LOSSES (both for cooling and induction).
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