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Old 04-24-2001, 03:27 PM   #1
tonytiger
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Talking What's wrong with the calculation?

Okay. When engine sucks air to the cylinder, it sucks it to pressure of the atmosphere (ca. 1 bar)http://www.howstuffworks.com/engine.htm When the gasoline burns it connects carbon (C)to diokside (O2) and produces CO2 as we all know. The oxygen in the air is already at the form of O2 so the relation with theese two matters are the (1 to 1). Hope you guys are following me. At this point we have cleared up that the energy produced is only caused by the amount of diokside. The more air the more the injection injects fuel. Next starting from the gas equation PV=nRT pressure * capacity = amount of matter * constant R (witch is one of natures constants) * temperature When the cylinder sucks air it sucks the constant amount of V and the pressure is also constant (depending ofcource the pressure of atmosphere). OK. The amount of diokside is the part we want no so when everything else is constant the amount of air only depends on the temperature T. n=constant * 1/T Hope you guys following my explanations... Then we can consider two situations n(1)=constant/T(1) and n(2)=constant/T(2). Dividing these equations we obtain n(2)=T(1)/T(2) * n(1). This is the end of the theory! So when drive at 30 degrees celsius and drive far to the north where the temperature drops to 20 degrees we should get air to cylinder 30/20 times we got at the wrmer area. So when the amount of air in the cylinder is directly proportional to the produced energy we should get 150% more power from our engines!!!! Can you guys figure out what or whith are the problem(s) of the theory? Try to solve it. I'd love to hear what you can say against it, obviously it can be tru. Anyhow, lets go and make some cold air intakes PS. The formula can also be used with the case of atmospheric pressure which on the face of earth depends mostly of the height we drive. There have been many post of the height reducing the power
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Old 04-24-2001, 03:30 PM   #2
tonytiger
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Oops sorry admins. I double posted this at this forum too. Feel free to delete it from NA powertrain.
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Old 04-24-2001, 03:34 PM   #3
SHADOWES
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I am at work so I can't work through all of the math a bunch to figure this out fo sure but, I think one part of the problem is that you co not ever suck in a full cylinders worth of air( does that make sence) even with a huge amount of boost you will never compleatly fill the volume of the cylinder with fresh air. the valves just arent open long enough, or big enough. you do make more power when it is cold thoe just not 150 persent because you are only using a small amount of you total displacement. sorry this is kinda half assed I know. I will try to post more latter when I figure out how right I am.
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Old 04-24-2001, 03:40 PM   #4
tonytiger
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Nice one. Can't say if it's the right answer, but keep it coming. What about others? Think
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Old 04-24-2001, 03:41 PM   #5
procrustes
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Temperatures start at 0 Kelvin -so 30C/20C = 303/293
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Old 04-24-2001, 07:01 PM   #6
BrandonC
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It's too late to do the math, but I believe for every 10 degrees that you cool the intake air, you get 1% more power?

I think procrustes Kelvin thought is the problem with your equation. You used Celsius instead of Kelvin, which will throw things off quite a bit. Just ask NASA and the Russians (?)....US vs. metric can cause issues!
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Old 04-24-2001, 07:40 PM   #7
BlackGT00
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Procrates has got it. With your calculation if the temp. went from 30 to -10 you would lose 300%. Now that would suck!
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Old 04-25-2001, 03:49 AM   #8
tonytiger
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Yes Procrutes got it, congrats! The answer is stupid as you can see and calls for a little bit of knowledge. It was supposed to be stupid but you guys were too smart to fall on to that

The idea of this text was to create information what the cold air really does for the engine power. The 30/20 is 50% more power was only cookie to cacth. But I still think that many who read the earlier text and didn't catch the aswer right away, thought something else what is causing the unreasonnable result. That is what I'd really want to know, because even with the right calculation (means using Kelvins) the reasults are pretty remarkable. The example in the first post however 303/293=1.034 brings ca. 3.5% more power. Other examples 303 to 283 brings 7% and 303 to 273 brings 11%. The power should increase significantly.

I'd be happy to hear some explanations and oppinions from you guys, which makes the power increase in practise less effective. That is the point of this post.

So anybody with thoughts bring them up. Let's see if we can make any conclusions about the effect of decreasing the intake air temperature?! Oh and you guys with this experience in any related situations including the mod, tell everyone about it. Thanks for reading, I'm waiting for some answers
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Old 04-25-2001, 05:30 AM   #9
Nat
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I don't have time right now, but I am currently in an internal combustion engine class here at school. Let me go through my notes and find some formulas and I'll try and post later if I have time.
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Old 04-25-2001, 06:20 AM   #10
BrandonC
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I know that engines are rather inefficient at actually making power from gasoline (30-35%?), so that may have something to do with it. If you're increasing the density of the air, you can add more fuel, but you're still only going to get 30% of the energy out of that extra fuel. SO, if you can add 11% more fuel (on a drop of 30 degrees), you'll get 30% of that in extra power, which is 3.3%. That works out to about 1% more power per 10 degrees.

Does that make sense, or is it just because I'm at work that it makes sense to me?
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Old 04-25-2001, 09:43 AM   #11
procrustes
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I think if you add 11% more air/fuel you will see approx 11% more power (I suggest you check your math - remember the original power efficiency is 30%). I think the other advantage of running a colder charge is the ecu may be able to advance the ignition more w/o detonation - I don't know if this is the case though.
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