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Discussion Starter #1 (Edited)
but i have a question. ok, its regarding air. well, as we all know, the closer to sea level or below, the better a car will run because of the amount of air. to put it loosly. well, i go to school in lubbock and i beleive we are 3300' above sea level. what im curious about is, when it comes to engine size ie number of cylinders. does the amount of air effect one type of engine more than another. i mean, if you take a v-8 versus a 4. we have 2 more cylinders, so does that mean we need more air to produce power rather than a 4 cylinder? i mean, im taking a logical view at this, because im a logical person. But...do you get my drift at what im thinking??? slap me silly if this is a dumb thought of mine.

correction*** ok here you....*we have 2 times more cylinders"
 

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Note to Self: Don't let my kids go to school in Lubbock.
 

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well the v8 takes in more air at sea level so it would take in more air at 3000 feet....so it affects it the same across the board....the 4 banger takes in less then the 8 at sea level...and less at 3000 feet...a 4 cylinder thats somewhat pepy at sea level...say a civic EX DOHC 1.6 rated at 127hp...might feel very anemic at 3000 feet vs a 4.6 making 215hp at sea level...but they both would feel very down on power
 

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I'm sure one of the engineers can find a formula to express this but my guess would be no - it doesn't affect one engine any more than another. The total air intake will be reduced the same amount in either engine given no changes other than altitude. In other words if the V8 makes 250 hp at sea level and suffers a 15% loss at altitude then the 4 banger making 150 hp at sea level would also suffer the same 15% loss. You might feel it a little more in the 4 cylinder since the altitude doesn't change the weight of the car and the V8 had a little hp to "spare" whereas the 4 cylinder was underpowered to start wih.

Think of a column of air over your intake, this column weighs a lot more at sea level than it does at 3300 feet (less of it overhead, shorter column) so it exerts more pressure on each square inch of your intake. When the valves open the combination of this pressure and the vacuum drawn by the cylinder will determine how much air gets into the combustion chamber during the time the valve is open. The overall amount of air at 3300' will be less simply because there is less pressure "helping" the air into the chambers. Call it negative boost for lack of me knowing the proper terms...
 

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doodaa is correct.

I, for purposes of this thread, will refrain from putting on my professor’s cap (I am one).

I will however strongly suggest to the first poster of the thread to double
check that math next time:eek:
 

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Discussion Starter #7
hahaha, im dislexic so excuse me for my math in the thread be all screwy. I know what i was thinking wasnt correct. but like i said, i think of stupid ish all the time and ponder on it. So i thought i would ask. i do see what yall are saying and its what i already knew.

Now...as far as going to school in lubbock. come on now, lubbock is a great place. im getting a BS in Electrical Engineering and im 1.5 years away from being done. as far as my math credentials go. i know my math. ive been through pre-cal, cal I, cal II, cal III, differential equations, and now for my last magic trick, linear algebra. anywyas, i know it was a dumb question but hey, what is they say, its only a dumb question if no one ask it or something?
 

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Having spent some part of my life studying EE and ME (I think is was during the
Mesozoic era) I know things cam become a blur.

That shall not lighten the scorn and ridicule that besets those who make funny mistakes.

The question wasn’t the least bit dumb, just the math:rolleyes:
 

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I don't usually go for the cheap jokes, spelling errors, etc. but I couldn't help myself. Especially after seeing AustinCougar's comment. I'm not going to bag on Texas Tech; my oldest sister went there, and she's pretty intelligent. Good luck with your studies; just hope that your profs don't see this post. :D

Marcus
 

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doodaa said:
In other words if the V8 makes 250 hp at sea level and suffers a 15% loss at altitude then the 4 banger making 150 hp at sea level would also suffer the same 15% loss.
Glad someone decided to answer his question. :rolleyes:

Another way to think of it is that the air is less dense at high altitude. That means less oxygen in a given volume. This is whaat causes the loss in power, and our own loss of power, "altitude sickness"
 

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Discussion Starter #11
Marcus: thanx, yeh i just wanna get done and graduate soon.

like i said, i know all about how air density and crap like that. it was just one of those ideas i got in my head when i knew the answer, but yet wanted to hear something different.

ill take hell for my math mistake. it is kinda funny. ahhh well....
 

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Even being the butt of ridicule can be educational ;) Don't let it worry you, only dumb question is one that you never ask.
 

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There is one good way to keep your car from feeling anemic at higher elevations. Shut the car off.

Shutting off the car and then restarting it again will make the computer relearn the air density, and it will compensate for the lack of oxygen. tha'ts what the BARO sensor is for.
 

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It can only compensate so far. The fact is that the air is less dense and contains less oxygen in a given volume. You also have lower air pressure, so when the car is trying to suck that air in, the lower pressure also pushes less volume of air through.

So, what you get is a lower volume of air going into the engine AND the volume that it DOES get contains less oxygen.

If you REALLY want to lessen the power loss, get a super/turbocharger. You'll still probably suffer a bit of loss, but it should be a lot lower than what you would get otherwise.
 
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