I'm in Denver and I've been told by some that the high altitude makes the 3.2 and 2.0 almost identical in performance (altitude + greater weight of engine and quattro).

I really want quattro but I'm not thrilled with spending $6,000 extra for it if the performance is the same. I've driven both and can't tell much of a difference.

Does anyone know what the difference between the two cars is at altitude?

If you can pull off the payments, by all means buy the quattro - and, as you've indicated, it's what you want. The price isn't too drastic when you compare a similarly equipped 2.0 to the standard features included in the 3.2. Turns out to be the same ~ $1500-2000 extra that quattro's cost since the early '90s.

There is a lot of talk of turbos outperforming more powrful V6 engines at high altitude and there is nothing to back that up.

I lived at 6500 ft for 5 years and my NA engines never suffered any dropoff in power or performance. If anything, less dense air would adversely affect a turbo engine, not the other way around...as it relies on re-intro of forced air to supply it's addtl power.

my mistake...

If I compare on a same trim level, my price comparison is $4000 more on the 3.2, for which you get quattro, the VR6 engine, and the S-line package. Not a bad deal in my book, but still $4K.

There are the laws of physics to back that up. At 6500 ft you have less air pressure than at sea level. As a result a NA engine is getting less air at high altitude resulting in producing less power. Car&Driver had an article on the subject in the mid nineties and provided a formula how to calculate the loss of power. I often visit Mammoth Lakes at about 8000 feet and according to the C&D calculation my then Audi V8 had a loss of 1/3 of power, i.e. from 240 to 160hp. And it was very noticeable comapared to my daily driving around LA. The car felt like a slug up there. On the other hand modern turbo engines are programmed to spin the turbo harder to compensate for air pressure deficit usually up to 9000 ft. So you're right on one point - the turbo gets a harder workout.

large V6 or V8 beater, which is what I have seen sworn to on these forums.

Virtually all engines have means of compensating for high altitudes. You may have driven to Mammoth occasionally, but I lived in Lake Tahoe for 5 years, 3 different cars, 4 and 6 cyl, and never felt sluggish power...not even a noticeable dropoff.

Talk to some people who live there year round, or a place like Reno, and see if their cars perform like crap on them. I think this idea is fantasy. Sorry, but laws of physics aside, it's not reality losing a third of engine performance at altitudes.

And to say a 2.0T beats a 4.2 V8 S4 at altitude is nuts! Yes, I have seen it said, LOL.

And yes, in high Altitude I've hung with American V8 cars up steep mountain roads in a 1.8T. By my calculations they were almost equal on power while the Camaro weighed a bit more. An S4 is a little bit different... but if it's down to 225 hp or so due to altitude... A chipped car would be right there with it because it weighs much less. Winning is one thing, but I wouldn't doubt it would be much closer than at sea-level.

Keep dreaming. No way S4 is down to 225 hp from 340 at altitude. Where do you get this stuff? What do you think would be going on with the engine during a 105 hp loss?

Camaro? Is that your example? Anyway, I beat large V8's up long grades to Tahoe with small V6's all the time. The V8 cars & SUV's suffer from weight, gearing, AT, and the other driver wasn't trying to prove something against your 1.8T

U.S., and presumably Canadian, gasoline is not volatile enough to produce the stratified charge. So, our engines aren't "full" FSI anyway.

i drive from sea level to 7k lots off weekends on bikes and na cars/trucks and the dropof, especially in lower powered vehicles, is huge. You get down to the valley and it's like a whole new car.

this idea of huge power losses of NA engines at altitude. 2 different things. read my posts and get on the same page.

Maybe your butt dyno is broken?

BTW, there's a guy over on the B6 S4 forum that has his V8 S4 and a 2.0T at altitude. He says up there they go about the same.. but when he comes down closer to sea level, there's a big difference.

just drove up there once in a while, like you. but, go ahead and dig your hole deeper.

hills and grades are what you are feeling and then brilliantly attributing to huge power loss, LMAO! Geez, I mean really, do you have any idea?

be faster than non-chipped anywhere, so what's your point?

overblown concept, and a sad argument that people here are ACTUALLY using to TRY and talk themselves into buying a 2.0T over a 3.2 or, better yet, that a 2.0T can beat an S4 at altitude. I mean really! We are talking about 200hp vs 340hp, and maybe 300 more lbs on the S4.

head handed to you. but, no worries, you're entitled to your opinion. it's been fun, actually.

it's at 4500 ft altitude, and gotta tell you, all the people who own all kinds of cars there are never seen or heard to get out of their cars and say 'sh*t, this 35-50% power loss makes my car feel like crap. It's sooo bad that i;m gonna move down to sea level, so that my car will drive properly'.

COME ON!!!!! get serious here people!

You sound like you have a lot of experience in this matter so could you please elaborate beyond "Virtually all engines have means of compensating for high altitudes." and "Talk to some people who live there year round..." so we learn something?
Can you explain how does a NA engine "virtually" compensate for the loss of air pressure at 8000ft altitude?
Living up there year round is a disadvantage IMO since you cannot compare to how the car behaves at sea level.
Since 1988 I spent at least a month a year at Mammoth Lakes and the Eastern Sierras hiking and skiing. We've spent our 2 week honeymoon up there - I hope that'll give you a clue. Since then I've been there regularly with the following vehicles: '84 Audi 4000q, '87 Acura Integra, '90 Audi V8, chipped '00 A4 1.8T Avant and '04 Volvo XC90 2.5T. How many times have I driven thru Tioga Pass at 9954ft? Thirty, forty times in all the cars above. All the NA cars I had struggled at these altitudes while the turbo charged ones feel as strong as at sea level. One of the best and safe places to compare is probably route 168 from Bishop to Sabrina Lake. It's a blast to drive on in the right car! The road has very few curves all the way up and starts in Bishop at 4150ft and ends at 9130ft, i.e. the car can be driven very fast all the way. I couldn't get the V8 above 50 to 55mph after reaching the 7000ft mark. The Avant had no problem going to 80mph all the way up. BTW on a weekend in the late 90s I bumped there into German BMW engineers doing development test runs in 5 highly camouflaged E46s.
You may laugh but IMO the thread starter asked a legitimate question about the 2.0T vs. 3.2 engines' performance at altitude. Denver is at 5300ft so the loss of power will obviously be less than at 8000ft but there will be some. Air pressure at sea level is 14.7 PSI, 12.32 PSI at 5300ft, 11.12 at 8000ft and 7.47 PSI at 18000ft.
Since I can't find the formula used in the C&A article let's keep it simple and assume that the loss of power at altitude is a simple function of just the ambient air pressure (if I remember well from C&D it's actually greater). At 5300ft the air pressure is 84% of the one at sea level and 75% at 8000ft. So 84% out of 250hp is 210 and 75% is 187.5hp. Factor in the weight of the 2 cars and you get the idea. As for your S4 example the 340hp car would have 255hp at 8000ft and a chipped 2.0T A3 around 240hp. Maybe there's something to that claim too.
Here's one article that confirms what I've found in practice: http://automobilemag.com/news/0602_turbocharger/
There are plenty more if you do a little search on the web.
I hope someone with a better knowledge of the subject can chime in.

Denver was in an uproar over the mysterious poor performance of their cars. It was the biggest story there since the alien abduction of cattle the year before.

By the way, despite your calculations per the C&D piece, your math is faulty. 240 to 160 would be a 50% drop, not 1/3 like you lamely claimed. Now, which is it? Do you or do you not know what you're talking about?

I can't get into the rest of your post here because it is terribly flawed personal opinion backed up by nonsense, despite you're insistance that you are well versed in the laws of physics, except basic arithmetic it seems, LOL!

Give it up.

Living at 7000 ft I favor turbo/supercharging because of the negligible power losses inherent to their design.

From a fellow audiworlder:


Google can be your friend...
User account number (aid): 4
Posted by Matt Daniels on 2005-06-07 08:04:27
In Reply to: 5.99999% :) posted by de (-eeez_nutz) on 2005-06-07 07:58:14

found this math formula:
Horsepower loss at altitude:
Note: elevation in feet.

hp loss = elevation x 0.03 x hp @ sea level
1000

If I'm doing it correctly, 200hp at sea level would lose 31.68hp at 5280 ft.

I found the formula on this site: http://www.ifsja.org/tech/misc/formulae.shtml

I also found this calculator: http://www.webcalc.net/calc/0757_bhploss.php

and we were only at about 2000 ft. I felt humbled by a car I used to own. I'd say my 330 is almost a match for an R32 in a straight line... If I was getting pulled by 1.8T jettas that weighed a bit less, I'm sure a 2.0T would be a match for the 3.2 in the mountains.

Even my bike in the mountains felt like it only had 50-60 hp. (99 R6)

with a real rebuttal.

n/m

I was asked how an engine can compensate for high altitudes by the Putzman as if it was a foreign theory or something. Okay:

Modern cars ECM continually 'manages' air/fuel mixture along with ignition, timing, etc, etc. Therefore, at high altitude, with less(or less dense) airflow to engine, ECM's will increase(or lean out) air/fuel in order to maintain proper balance of air/fuel mix under all loads. If not, then at altitude engines would run excessively rich which would cause a whole slew of problems.

The drops in power you nimrods insist is happening is likely due to driving conditions, not the air.

You technical cripples who have crawled out of the woodwork in demanding that NA engines run at 1/3 to 1/2 less power at high altitudes outta have your heads examined, or take a look in the mirror.

I'd recommend he starts with 2nd grade math first. Thank you for the useful info about calculators!

downshifting!!!!!!!!!!! Geeez! It is just a absurd notion... coming from you...the self proclaimed physics guy.

I would be ashamed to try and put over that V8's can't get above 55 mph at 7000 ft.

a 50% decrease, not 1/3. Did you or did you not say that 240 to 160 was 1/3 loss?

Why don't you be honest here and admit your mistakes instead of cowardly trying to transfer them onto me.

You are amateurishly calling me on stuff when you don't have your own house in order and your posts are full of double talk and miscalculated numbers of your own making.

Don't blame it on me now that I've correctly pointed this out.

Have a nice...drive...up to 7000 ft struggling to reach 55 mph, LOL!

Dave buddy,
you are correct on one level. While it is true that modern ECUs will adjust air/fuel mixtures with barometric/atmoshperic changes, the object is not to maintain overall power output but rather a smooth running engine.
Fact: Power is proportional to amount of fuel burned over time.
Fact: Amount of fuel that can be burned is directly proportional to amount of oxygen present in cylinder chamber on compression
Fact: Partial pressure of oxygen (21% at sealevel) decreases linearly as altitude or barometric pressure decreases.
NA engines have NO way of increasing this partial pressure. Forced induction (ie turbocharging and supercharging do just this!) increases intake manifold pressure with the direct effect of increasing the partial pressure of oxygen thus increasing power. At altitude, the turbo managment is able to adjust and better maintain overall power output much better than NA engines.

Turbos are better at climbing hills as the turbo is quick to spool up under engine load. So, the V8 driver would need to keep his revs up thru proper use of gears or else he could have the turbo car pull on him, as you described.

And if you don't know why it's funny.. that's even more funny. You're just digging your own grave with terrible misinformation and incorrect assumptions.

you start delving into amateur physics. Pleeease! : )

At least comparisons of a turbo car vs larger NA engine at altitude.

Maybe you need to take "Reading 101" before you try and teach "Physics 101" or "How modern NA engines compensate for atmospheric pressure drops in order to maintain equal power at high altitudes compared to sea level power outputs 101". That last one has me rolling on the floor.

Keep trying to come across as a genius, I'm really enjoying it!

and study the basics of how engines generate power. Thanks.

Fact: The power and smooth running engine are not mutually exclusive as you describe.

Fact: The turbo will force more air, but less dense(oxygen rich) air resulting in a maintained performance level, not increased. In other words, it is running more boost to compensate, not improve.

Your turbo analysis is correct though, as to it's function on airflow and re-ignited exhaust.

By the way, my argument was never with performance of turbos at altitude, but rather these claims of 35-50% loss of power at high altitudes of NA engines. You aren't agreeing with that ridiculous idea, are you? How about Putz' claim that his V8 couldn't get past 55 mph at 7000 ft? Come on! Let's see you get on his side there. I'd love to hear the explanation on that one.

high altitude.

quote:
"In other words, it is running more boost to compensate, not improve."

-------------------------------------

Like I said, learn how a turbo works.

zippo! i'm glad you're enjoying it. dummies usually find humor in almost anything.

no genius, not at all. it's sad that you would say that as it really puts into focus your ignorance on the subject.

now try to understand that very simple function of the modern engine. it's not my idea you know.

While you're at it, why don't YOU actually post some concrete evidence that NA cars don't loose power.

To put things in perspective, an A3 2.0T will take out A3 3.2 at 6500 feet.

That's what this really comes down to.

Now I know that you have never claimed there is no power loss with NA engines at altitude, but are allowing many here to believe that stance as you are rather enjoying yourself.

Since I know you know there is indeed power loss, why don't you educate anyone left reading this POS thread with what the correct way of calculating it with your VAST physics knowledge? Oh right, cause you're rather enjoying yourself :-p

how about spinning faster, passing more air thru turbine, to maintain boost. you're splitting hairs, turbo boy.

anyway, let me know how it turns out when you take on that viper at 5000 ft.

2.0T vs 3.2 at 6500 ft, it would be close, but that is 200hp vs 255hp. My objections have been more to the 200hp 2.0T matching the 340hp 4.2 V8 S4 at altitude. Or a 4 cyl to a V8. That is laughable, and it has been claimed also.

Any engine will lose a slight amount of power due to thinner air, even your lawnmower. But 'slight' is the key here. I have spoken against this idea that they will lose 35-50% power and/or not be able to exceed 55 mph at 7000 ft. Is that not ridiculous? It has been said and repeated here by at least one person.

Therefore, it is not my job to clean up this post, but everyone's job to actually read each post for what was stated and what wasn't.

You dig?

I think the 2.0T that was close to the 4.2 V8 was chipped. (check the torque on a chipped 2.0T, it's impressive)

I don't know why someone said they were limited to that speed in a V8.. must have been a steep grade and heavy trailer ;-) Even a Geo Metro could get up to that speed.. it'd just take longer than at sea level :-p

But yeah, I knew what you meant ;-)

Of course.. I'm having fun here too.

And there's no way my car is taking a Viper as is at any elevation that has roads. However, it will take an NA 3.2 out easily. :-)

So back to the topic that started this entertainment..

A3 2.0T vs A3 3.2. If those were my only choices, I'd take the 3.2 as the 2.0T is not available in quattro, which I would find more useful in the mountains than forced induction. However, between an A3 3.2 and an A4 2.0T quattro, I'd take the A4 hands down at elevation.

and that's what it's all about...differing opinions or perspective. It's too bad it has to get ugly sometimes. I felt like I was being jumped by a bunch of people here. In trying to keep up, if I didn't make myself clear at times, well, it wasn't easy considering some of the outrageous power loss claims being made.

Makes you wan't to go shoot your NA engined car, if that is to be believed.

... since your base is 240, the delta is calculated as the fraction or percentage of that. If you started with 160 and added 80 hp, you'd have a 50% increase, but that's not the condition under discussion.

Yeh, that and the S4 needs to keep its revs up. But, I was having fun trying to point out the more ridiculous aspect...which turned into a lot of blowback...most likely from the turbo owners.

Yes, 160 to 240 is 50%. 160 of 240 is 2/3.

I live at 7000ft near Pikes Peak. Ive driven both the 2.0 and the 3.2 A3 here. The 2.0 doesn't have trouble holding its own against its brother. During the annual hillclimb it is impressive to see the difference in power between NA cars at the bottom of the course and at the top ~6000 ft higher. Turbo guys dont suffer as much.

What altitude is the starting point and what % of power is the NA car(s) losing to 6000 ft? Also, it is a hill climb. And you have a weight situation there(2.0T vs 3.2) coming into play.

My point all along has been that as long as you are not going up a grade, even one that may seem inperceptible, that your NA car will not suffer a noticeable dropoff in power at altitude.

I lived at 6300 feet in Lake Tahoe for 5 years, drove all around at altitude there...drove from sea level to above 7000 feet all the time...drove down to Reno and back(2000 ft difference) a few times a month. And in 3 different NA cars I did not experience lack of power, sluggishness, etc. UNLESS I happened to be going up hill! Which would be the case anywhere.

This thread is going a bit wacko, with lots of BS flying around. Speaking of flying, I'm probably one of the few people here who have taken normally aspirated engines to higher altitudes than being discussed now. There certainly is power loss at altitude, but not as dramatic as the figures thrown around earlier. There's about 20% loss at 8,000 feet, 30% at 12,000. A properly designed induction system can recover some of that due to ram pressure, but that's a bit more difficult in a street vehicle application. A turbo is often used to maintain sea-level power at higher altitudes (termed turbo-normalizing) thus increasing an aircraft's service ceiling up to 30,000 feet, well above the typical non-turbo'd limit of around 18,000 feet.
One of the reasons one doesn't notice much of a loss at higher driving altitudes is that we rarely use wide-open throttle on the street. Unless you're really, really pushing hard, even a normally aspirated engine will provide all the power you need. Your pedal might be depressed slightly more, but most of us drive by the tach or speedo, not throttle position. With modern drive-by-wire systems, even the pedal position can remain the same if (big if) the ECU is programmed to correlate pedal movement with airflow rather than throttle position. I haven't taken my TT much over 4,000 feet, so I don't know how the 1.8T MTM Stage I ECU I've got deals with that.
So back to the original question - yes, a turbo'd engine will lose less power at altitude than a normally aspirated one. Exactly how much depends on the ECU programming (e.g., limiting boost based on relative or absolute pressure), and I haven't seen the engineering data (but I'm sure Audi has it).

that is done either manually(small prop engines) or automatically(turbojets) as altitude is increased? Is it not adjusting air/fuel mixture? The ECM's in cars do that...not only at altitude, but constantly.

Older cars(mainly pre 80's) had altitude compensation capability in the form of a valve or solenoid that would come into use at high altitudes.

1) Climb performance, whether it be in an airplane changing altitude or a car going up a hill, depends on "excess power". This is the amount between what's needed for straight-and-level cruise and the potential output of the engine. At altitude, that difference decreases, eventually becoming zero if you go high enough - you simply can't climb anymore. A turbo'd engine can raise that limit significantly, since it can pressurize the induction system well above the atmospheric value.

2) Fuel consumption for a given speed is usually reduced at altitude. Besides there being less drag due to less dense air, the pumping losses of a piston engine are also reduced since the throttle is more open.

Keeping the A/F ratio correct does not compensate for the loss of power due to having less oxygen to burn the fuel with. A proper mixture does affect combustion temperatures (don't want to melt those aluminum cylinder heads) and combustion products (keeping the catalytic converter and the EPA happy). Certainly, mixtures that are way off can either quench the combustion or invite pre-ignition, but there's a fairly wide range where power output is within a few percent of optimum.

yeah right. I made that poor BMW scream. Vanos was working overtime.

340x.75= 255 hp pushing 3800 lbs = 14.9 lbs/hp

Look at GTi 200 hp pushing 3300= 16.5 lbs/hp lbs racing and it's very close. The S4 would win but it wouldn't be a blow out.

Look at the A3s

25% power loss for a heavier 3.2

19.2lbs/hp

2.0T

200 hp (I'll even give you an bonus 10% loss due to altitude) gives
18.3 lbs/hp

accounting for weight difference

The 2.0T would be faster and it does have less weight.

That was your original point, as this is what you stated in your first few threads. Now ur trying to change it.

"200hp 2.0T matching the 340hp 4.2 V8 S4 at altitude"

wow.

whatever...your 235 hp(or so) should have dusted his 180....at 2000 ft...no question.

Something else did you in. Jettas aren't that light either.

Am I being argumentative? Well, show me 1.8T jettas whipping 330i's at sea level OR 2000 ft, on average, and then I'll believe it's the real deal.

the bigger question is if you want the haldex or not.

come to the aid of some other spuds here who can't handle the fact that their glorious 2.0T's aren't REALLY as fast as S4's or other V8's at sea level, in the mountains, or anywhere. Change your underwear. : )

put his S4 up against a Viper

:-)

Ha, according to your convoluted calculation the S4 would have to be at 8000+ feet to get to your 3%/1000 power loss figure. Of course, the 2.0T would be immune to this same high altitude at 8000 ft, right? Give me a break!

I'm lurking still to shoot down your factless claims of what a 2.0T can or will do against NA cars with significantly more HP, slightly heavier weight.

Why stop at the S4? Why not say it now: the mighty, thin air loving 2.0T will beat a G35, TL, IS 350, 330i, Mustang GT, Corvette, on and on. Come on! Let's hear it!!

THAT is my point throughout this thread. I am being kind of a jerk about it though, I admit.

raggin now as this thread has turned into an excedrin extra strenght excercise.

Aircraft engines tolerate poor A/F ratios better than automotive - most still have manual mixture controls. Students frequently get horrible fuel consumption due to failing to lean out the mixture, but there's no discernible performance loss. We normally lean it down until one cylinder starts getting a bit rough, and then richen it up slightly from there. With better instrumented engines, you use peak exhaust gas temperature, but there's still very little performance change from 50 deg lean of peak to full rich.

not trying to bash it, I almost bought one awhile back. As to the turbo at altitude vs the NA engine, you're not going to get there based on that specific issue alone. Both will do fine at altitude, no one is ditching all their non-turbo engines because they live in the mountains, and strong 6's or V8's are not being humbled by any turbo that comes along, so it is a reality check, in reality.

Time to get back to real discussion re the A3...

sorry for being an argumentative SOB, and for any facts I screwed up along the way.

that is a refreshing way to compare the two, thx.

Just damn.

We already know your math is lacking, maybe altitude affects more than just cars? You have a problem with math involving 50% and you're ignoring 50% of the a/f equation.

You seem to think the normally aspirated engine can adjust the amount of air to compensate for the higher altitude. Yes, ECM's continually manage the air/fuel mixture, but <b>in N/A engines ECM's cannot control how much air goes into the mixture</b>. At higher altitudes, there is less oxygen, so all they can do is to reduce the fuel to maintain the a/f ratio. Less air &amp; same a/f ratio -&gt; less fuel -&gt; less power. It's like taking your foot off the accelerator pedal.

In turbo engines, the ECM has control over both variables: air and fuel. It can increase the turbo boost to compensate for the lack of oxygen. Therefore, to maintain the a/f ratio it doesn't have to reduce the fuel.

Unless you have turbo-charging or supercharging or NOS injection, how can you increase the oxygen to compensate for altitude?

I guess it is just easier to wave intArw3b pens around than look at data. Simple MAF logs at different altitudes will prove a point.

right as an American. That doesn't let off the other nitwits here on some of their stmts. I'll stand by everything I said except the 50% power loss calculation. I was incorrectly calculating up when I should have been down(240 to 160).

This is a spirited, if nauseating discussion, where people will at least increase their knowledge level, if nothing more, as a result.

misinformed claims here, such as:

*35+% power loss of NA engines at altitude

*340 hp S4 taken by stock 2.0T's at altitude

*inability to maintain 55mph at 7000 ft

*330i's having it handed to them by stock 1.8T Jettas at 2000 ft

How about it?

As a side note, I live at ~7000 ft and bought the 2.7T motor instead of the 4.2 V8 because it has more power at elevation.

:)

<ul><li><a href="http://www.csgnetwork.com/relhumhpcalc.html">Horsepower calculator</a></li></ul>

Thank you. I will happily admit that I don't have all the technical bases covered, but VERY few people here do.

I am sure you don't like to see a ridiculously long and inflammatory thread like this, and maybe my style can be provocative at times to illicit a response or dig deeper to see who is actually saying what. But I will take the heat that I bring upon myself, and usually admit when I'm wrong, at some point.

My original post here about altitude being a non issue was too general and overreaching. I backed off of that later, while still attempting to call others on their claims that altitude is severely hampering NA engines.

After seeing several threads that openly implied a 2.0T could, and would beat a 3.2 or 4.2 at anywhere from 2000 to 6000 ft level, I tried to counter that over inflated touting of the 2.0T, even if unsuccessfully.

It would have been nice to see some 3.2 or 4.2 owners chime in here in defense of their engines/cars. But, the blowback all seemed to come from a reactionary turbo crowd instead.

anyway, look at ome of the other posts here and see what you think.

if you want to confirm the effect of altitude on engine performance, just talk to any pilot you know. Of course, an airplane gets socked by altitude twice -- engine performance is reduced, while the power requirement is increased. This is aviation 101.

of a reach over simply driving in the mountains. It was implied over and over here(and in a couple other threads) that anybody with a 3.2 or 4.2 was going to be taken by 2.0T's at altitude, while ignoring the many other determining factors. Are you comfortable getting behind that?

Go look at some of the other posts here and see for yourself what I am and HAVE been talking about all along. Instead of just hammering on mine. Sound reasonable?

:) just teasing, but another example of "FACT vs OPINION"

I'd have to run the numbers. I have little doubt that a 2.0T will beat a 3.2 at 10,000 feet, but I'm not going to make a sweeping generalization.

About 10 years ago, an airplane crashed on takeoff from TriCounty airport north of Denver. The primary cause was that the Texas-based pilot failed to factor altitude into his takeoff calculations. The altitude there is about 5000 feet.

So don't think that by dragging airplanes into the discussion we're talking about 30,000'.

talked about hill runs in Colorado to 6000 ft between the 2.0T and 3.2 (A3's I believe). I then asked at what altitude the run started. Because if it started at sea level, the 3.2 would be long gone due to it's HP and gearing advantage. If it was from, say, 4000 to 6000 ft, that would be another story.

Anyway, my point all along has been to dispel the idea that small 4 cyl turbo cars will beat large 6's or V8's with much more HP in the mountains. I stand by that.

you don't like what I have just said so now you are degrading. It's a common method to belittle someone. The question is why?

You compare a pilot taking off at 5000 ft and forgetting to adjust his trim. It's a no-brainer and not a legit comparison of driving a completely different car engine in the mountains.

But, whatever...

the discussion was about cars, not airplanes.

The airplane is perfectly relevant here, because it has to do with the effect of altitude on engine performance. The airplane is simply more vulnerable to altitude since its takeoff power requirements go up as the power available goes down. The accident had nothing to do with trim.

obviously it's not exact, there are a lot of minor variables i'm not including (there is *some* efficiency loss of the turbo for example, and gearing and such) but in general, the further you get above ~8000 ft, the 2.0T A3 should start pulling on a NA A8 8cyl.

A8 w/v8 A3 w/2.0T
hp 335 207
curb weight 4288 3263

hp to weight 0.078 0.063
hp to weight @ 1000ft 0.076 0.063
hp to weight @ 2000ft 0.073 0.063
hp to weight @ 3000ft 0.071 0.063
hp to weight @ 4000ft 0.069 0.063
hp to weight @ 5000ft 0.066 0.063
hp to weight @ 6000ft 0.064 0.063
hp to weight @ 7000ft 0.062 0.063
hp to weight @ 8000ft 0.059 0.063
hp to weight @ 9000ft 0.057 0.063
hp to weight @ 10000ft 0.055 0.063
hp to weight @ 11000ft 0.052 0.063
hp to weight @ 12000ft 0.050 0.063
hp to weight @ 13000ft 0.048 0.063
hp to weight @ 14000ft 0.045 0.063

So the turbo engines have some dropoff in power with altitude -- it just isn't as severe as NA engines. I've been unsuccessful in finding out what that dropoff is, although I could probably do some logging and find out.

Thanks for posting some actual numbers, though.

(BTW, you meant 2.0T, not 3.2, right? Your post includes both.)

the basis for choosing a 2.0T over the 3.2? An iffy performance edge that will win a race at &gt;8000 ft?? Assuming the more powerful car isn't long gone by then??? That was the original subject of this thread.

The A8 to A3...has to be a better comparison. I mean the weight and mass alone are going to affect the A8 anywhere. Kinda puts things in perspective, eh?

Anyway, good talking to you.

based on your statement: "the idea that small 4 cyl turbo cars will beat large 6's or V8's with much more HP in the mountains". 8000 ft is not unreasonable altitude at all.

Indeed, I regularly drive to 10,000 ft.

the large powerful 6's and V8's in cars such as the S4, G35, IS350, 330i, Mustang GT, Corvette...not a car that weighs 1500 more lbs.

So did I over Mt Rose summit down to Reno many times. Not to mention up the long grade over Donner summit(7200 ft) from Sac into my home at Tahoe all the time. I really felt the steep grades affecting engone performamce much more than Altitude.

By the way, your 2.7 twin turbo is hardly the same as the 2.0T vs the 4.2 V8...at any altitude. So I can easily appreciate why you would choose that at your altitude. Yes?

Since the press release says 200 HP crank, but independent dynos are showing it's closer to 220 HP crank.

So let's nail this down..

Let's say 4000 feet, 30.14 inches hg, 20% humidity, 50 degrees F. NA engines in those condition are down to 89.7% efficiency compared to sea level.

so from 250 HP to 224.25 HP, and 236 lb ft torque to 211.7 lb ft.

<b>A3 3.2 @ 4000 ft</b>
224.25 crank HP
211.7 lb ft torque
3660 lbs
Each HP has 16.3 lbs to push
each lb ft of torque has 17.29 lbs to push

<b>A3 2.0T</b>
200 crank HP
207 lb ft torque
3329 lbs (w/ DSG, for more fair comparo)
Each HP has 16.65 lbs to push
Each lb ft of torque has 16.08 lbs to push

So far, the 3.2 has ever so slightly better hp to weight ratio, and the 2.0T has more advantage on the torque front. Before delving on, one important thing to remember is that we're talking about PEAK hp and torque. The 2.0T has another advantage of having a flatter torque curve, meaning more area under the curve over the rev band. Based only on this so far, the 2.0T is already ahead.

However, you also need to calculate in the extra loss from the AWD (there is some). I don't know the specifics of the haldex AWD vs fwd on the A3, so it's pointless to calculate. However there is definetly more loss with the quattro, so more advantage to the 2.0T (assuming no snow ;-))

Then we have another mystery of the actual crank HP the 2.0T makes. We know it's more than the 200, but maybe the 3.2 is also underrated.. so more unknowns into the mix.

Finally, many 2.0T owners will chip the car. While chips may become available for the 3.2, they won't do much. The chips for the 2.0T put the power out of the league for the A3 3.2. While one could argue that you could supercharge the 3.2, comparing the price of a chip to the price of a supercharger setup is laughable. (but an 3.2 supercharged would be excellent!)

However, despite that the 2.0T is a better engine choice for higher altitudes (and even sea level IMO), I'd still choose the A3 3.2 quattro DSQ over anything with fwd only at elevation. The AWD is something that even in summer I don't want to give up.. Put an A3 3.2 quattro vs A3 2.0T fwd up against each other on a snowy road.. add a steep grade up. It doesn't matter if the 2.0T has a gt35R turbo and makes 500 HP, the stock 3.2 will still easily pull away (duh).

Like I said before, I'd take the A4 2.0T over the A3 3.2 though, as the A4 is available with quattro, and I could still chip it and show the A3 some hind quarters.

So, as I've pointed out, it doesn't just come down to power when selecting which version of the A3 to get for the mountains. If the A3 2.0T becomes avilable with quattro, that's the obvious choice <i>in my opinion</i>. But until then.. quattro baby!

BSW has it right at 3% loss per 1000 feet for NA cars. Thinner air = less air. Less air = less fuel in order to maintain the A/R ratio. Thus the NA car's loss of power the higher you go. Turbos build pressure and can maintain the same power levels regardless of altitude (you do lose turbo efficiency -- ie more lag the higher you go, but you'll ultimately get the same amount of power).

You should notice some power loss (only at full throttle, of course) at 4000-6000 ft. If not, you should get your butt-dyno recalibrated. At 10000 ft, the power loss of NA engines is pretty significant.

And driving up a steep grade is precisely where you need max power the most...

<a href="http://forums.audiworld.com/a3/msgs/48581.phtml">http://forums.audiworld.com/a3/msgs/48581.phtml</a>

even to you in a couple posts, right?

I wouldn't say the same of 2.0T against S4, G35, IS 350, Mustang GT, etc...right? Because THAT is what some implied here in their hype about 2.0T's and even 1.8T's, even if not specifically naming any cars.

Look back thru the posts and check it out...not just mine.

To answer your questions, technically the hill climb starts at 9300 ft and ends 14100 feet. If you talk to the drivers, power loss for NA cars is ~15% over this altitude. For am unlimited class car 600hp V8 will sacrifice 90HP which is significant enough to feel. Since all cars (barring Turbo/SC cars) experience the same loss, the difference in lap time is not relevant.

With respect to uphill issues...again simple physics. When running up hill you have an additional force (some % vector of gravity that you are trying to overcome dependent on the grade). Both cars experience this same vector (yes larger for heavier cars...again advantage 2.0T)

2.0T and 3.2Q A3's at altitude. It was whether the 2.0T is equal to or actually better than the 3.2. Under normal driving, even at his altitude, the answer would have to be no, at 255 vs 200...although the performance is close between the two to begin with due to the 2.0T torque and blower advantage at low end.

to say nothing of the chipping potential of the 2.0T

A8 w/v8 A3 w/2.0t S4 w V8 chipped 2.7T
hp 335 207 340 305
curb weight 4288 3263 3957 3814

hp to weight 0.078 0.063 0.086 0.080
hp to weight @ 1000ft 0.076 0.063 0.083 0.080
hp to weight @ 2000ft 0.073 0.063 0.081 0.080
hp to weight @ 3000ft 0.071 0.063 0.078 0.080
hp to weight @ 4000ft 0.069 0.063 0.076 0.080
hp to weight @ 5000ft 0.066 0.063 0.073 0.080
hp to weight @ 6000ft 0.064 0.063 0.070 0.080
hp to weight @ 7000ft 0.062 0.063 0.068 0.080
hp to weight @ 8000ft 0.059 0.063 0.065 0.080
hp to weight @ 9000ft 0.057 0.063 0.063 0.080
hp to weight @ 10000ft 0.055 0.063 0.060 0.080
hp to weight @ 11000ft 0.052 0.063 0.058 0.080
hp to weight @ 12000ft 0.050 0.063 0.055 0.080
hp to weight @ 13000ft 0.048 0.063 0.052 0.080
hp to weight @ 14000ft 0.045 0.063 0.050 0.080

played loose with some of the details in order to get the more rabid and entrentched element to admit that their's is not gospel, and that there is a gray area of performance between turbos and NA at altitude, car to car. That's all.

P.S. Oh, and this concerns cars, not airplanes. You know...rolling resistance, no lift, etc. LOL!

a good guy. I learned some things from you, thx.

then even compounded my mistake by rubbing someone's nose in it with my incorrect number. He was right, I was wrong...info overload at too fast a pace. What can I say?

For posting flame-wars to a public forum. Any PR hack should know better than that. Let's hope AOA doesn't find out your "little secret."

One PR hack to another, brother... :-p

<img src="http://i13.photobucket.com/albums/a279/iMryanmac/LOL/apr.jpg">

a "normally aspirated" IC engine loses 5% of it's peak power.
All due to air density effects.
It's the fact. get a thermodynamics book and do the math.

try pulling a 15,000 lb trailer over Vail pass in a gas truck, then the same in a turbo diesel. i guarentee you will know the truth after that

a heavier engine and thus a heavier car can be beaten by a lighter car with less HP. add weight and loss of power at altitude together, and you can understand how my stage 2+ B6 A4 walks on NA 4.2L b6 S4s here in denver all the time. My car is 3600lb as is (try driving that at any altitude at 170 bhp stock...hehe)

and it is not the physics of just pressure loss at altitude...but quite simply the technical term for these systems...its called forced induction. a turbo will cram more less dense air at altitude into the engine, whereas the NA engine will simply cram the same amount of less dense air into the engine. hence "forced" induction. more less dense air can be crammed in there by a turbo because it is (waits...hears crickets chirping) less dense...hence it can be compressed...made more dense...and allow the engine access to more oxygen...and that is what this is all about...because without O2, there is no fire, and no horsepower. lets examine what happens when more oxygen is added to an environment...look into the apollo 1 incident...a pure oxygen environment burned up three perfectly good NASA pilots on the launch pad in all of 2 minutes. so...we can then assume that more oxygen makes more fire, makes more horsepower. this is why NA engines suffer at altitude more than turbos. period.

I'll take you and your dog on anytime smart*ss. Or IS that you panting outside the window of your allroad?

20% loss at 8,000 MSL and 30% at 12,000 come directly from the Cessna 172R POH, using a 160 HP, fuel-injected, normally aspirated Lycoming IO-360, with an induction system incapable of recovering RAM pressure.

Real-world atmosphere is not quite what the undergrad classroom would have you believe. (And yes, I took thermo - a lot of it - on the way to a mechanical engineering degree a long time ago.)

We live at 8500Ft elevation. Wife drives 3.2 TT. It is very responsive, especially with the DSG. However, its passing power is much lower than either my allroad or previous S4 with same "rated" 250 HP. Have test driven both A4 and A3 with 2.0T. Seat of the pants says 2.0T performance at our altitude is about equal to NA 3.2 TT. If you really want to feel the difference a turbo or two makes at altitude, drive the Pikes Peak Highway! By the time you reach 14,000 FT in a NA vehicle you will be wondering if you will make it the last 110 feet to the top! With the turbos, you still have plenty of power.

I even gave a wink as a clue....

Granted, I was being a bit of a provocateur, but you really need to have your blood pressure checked. Oh, and the point of the post was that putting any info or effort in this thread at this point would be utterly pointless.

you thought things had quieted down so you could come in and take cheap shots. Real gutsy.

I can identify...a back door type like you.

Say what you will about me, but you have shown you've got absolutely nothing. 6 or 7 posts, pure crap. No discussion, no alternative view, just snyde remarks. You outta be real proud.

I said, real gutsy to wait until the dust has settled and then go after someone. Provocateur? More like a bottom feeder.

my blood pressure if you'll check for a backbone.

This thread had been dead(mercifully so) for several hours, and suddenly there was not 1, but 3 cheap shots posted here by you. I know you were probably temporarily reveling in your actions and didn't expect anything to come back at you, but you shouldn't have the naive expectation of being able to slink around here and not be called on it.

Now, you can deny it, or put any kind of spin on it that your dry and weak humor demands of you, but you have proven very clearly to be a nothing more than a cheap shot artist here.

Have a nice day.

...then why are we even arguing about horsepower loss? For partial throttle applications, you are arguably not constrained by horsepower.

In that case, I'd have to consider other factors like gas mileage.

Dave, care to comment on which one is better in that 'normal driving' situation?

Sure, I'll comment. What I was talking about, despite my various mistakes along the way(in attempting to deal with a bombardment of posts) was mainly to dispute the following:

&gt;1/3 HP loss of NA engines, while implying that turbos were completely unaffected at same high altitudes. Yes, examples are all over the place here...and NOT talking about &gt;8000 ft in almost all instances.

claims of very sluggish performance of NA engines(only) while driving in the mountains, with no consideration(at least acknowledged) of going up hills and/or steep grades.

the claim of one who said he couldn't get his V8 A8 above 55mph at est 7000 ft altitude.

individuals with hand held stop watches or store bought testers claiming their stock 2.0T beat either their buddy in an S4 or his 0-60 time in Denver.

insisting that a 330i was no match for a stock 1.8T Jetta at 2000 ft.


a claim of a NA V8 having to struggle just to make it the last 120 feet(only?) to 14,000 ft summit of Pike's peak

How's that for starters?

So, if you listened to many of the 2.0T diehards here, you would have been given the impression that anybody with an NA engine was going to have sluggish performance and struggle around the mountains in their cars. While the turbos would rise above all this and fly on wings of power, all the while knocking off one large 6 cyl or V8 after another.

The reality is much closer as NA engines do not suffer THIS much, and turbo engines can't compensate THAT much.

I don't care what Cessna told you.
Get your book out and review.
It is what it is........... You really can't argue with it.