Track times and Elevation

[laserspeeddemon]

Originally posted by QuickerDSM


It will make a difference though. It will be the same amount of pressure, but the air is denser at lower elevations so the VOLUME of air will be greater. Denser air means more volume per cubic foot of space and it doesn't matter if it's compressed or not. A car will not run at 25k feet because the volume of oxygen molecules is almost non-existent.

By your definition an engine should make the same amount of hp at 14psi of boost no matter what, and we all know that is not true.

Mike

Volume is the amount something can hold. Not the amount of molcules per cubic feet, thats what density is. For example a car that has 2.0L has a volume of 2.0L. Pressure is described in many ways, pounds per square in, BAR, Pounds per feet, Kilograms per Cubic meters, ect. Denisty in the air is caused by pressure of air above it being pulled down by the Earths Gravity. In a turbocharged car the air is being made more dense by the air being forced upon it via the turbo. Since the area is small it is measured in PSI or BAR. Pressurzation effects density of any Element , especially in Liquid of Air Forms; but is applicable to Solids.

 

[hoffman]

its a rule of thumb in colorado that you run a second slower than everyone else.

yes you are still compressing air, but there is still alot less of it. the example in the other thread is perfect. in AZ (4k' asl) i ran a 15.1@88 ( i think, can't find the slip) with only an intake, ui/c pipe and mbc. 2 weeks later i ran at the same track with a 3" turbo back and a cfdf clutch. same psi. that got me a 14.7@91. most guys at lower elevations would have seen very low 14s to high 13s with the same mods.

elevation does effect a cars performance. more so in n/t cars. but the effects are still there in turbo'd ones as well.

 

[laserspeeddemon]

I agree, it would have some minor affect. But a turbcharged car shouldn't lose over a second. I could take that into effect on an N/T car.

 

[laserspeeddemon]

Originally posted by Oreopride18
Quicker is correct on this. Take it from a guy who has family in Colorado and decided to "attempt" and afternoon jog there. In Colorado I'm breathing the same amount of air as I do in Florida and I'm moving at the same pace as I would here. Also, my breathing rate didn't change in any way and my lungs still took in the same amount of air. But you know what?

In Florida I can run a 7 minute mile. In Denver I'd consider myself lucky to pull a 9 minute one.

And the best I ever got stock was a 9.5 on horrible tires (hoping for 8.5's on the new ones ) 1.91 60 footer was the best I ever got on the stock slipping 120k mile clutch. I can pull off consistant 1.86-1.94's right now but I'm hoping the stickier tires will let me launch a little higher and get 1.75ish.

The problem with comparing stock times is it can never work out on older cars. I have stock shocks but if I replaced them I can promise my MPH would pick up 3MPH or so in the 1/8th and I could still say "I'm stock." Or I could have 225/45/16's ZRs on a car and still get away calling it "stock" next to a set of 205/50/16 H-rated tires.

Your lungs work the same way an N/A car does. Now if you put a turbocharger to your mouth, your lungs would explode. So there not really a way to describe that

 

[QuickerDSM]

Thanks for clearing up the 'density vs volume', I knew what I wanted to say, I just got the terms mixed up.

Air density is still going to have an effect though. It's the same reason a car (FI or NA) will run harder when it's cold outside, because colder air is denser air. It's also the same principle as an intercooler. The whole reason to cool the charged air, is to make it more dense.

Mike

 

[laserspeeddemon]

wow good points.

Pressurization causes heat, heat makes air expand especially as it moves in an open area. In a closed area it keeps its heat and air density is low. Intercoolers provide the effect of cooling to reduce the after effects of pressurization air. Intercoolers are used to do that. Also Intercoolers help to reduce untimely ignition or knock. But the effects of an Intercooler takes place only after the air is already in a closed environment and has seen the affects of a turbo. The air in a intercooler has no option but to cool. Since the air is forced to flow by the colder surface.

Turbos create pressure which increases density but pressure causes heat which reduces density. Intercoolers cool the air which increases density but the area the air must travel allows the air to expand which decreases density. Funny how that works huh?

 

[hostile]

I heard forced induction cars loose more power than na cars in higher elevation.

If you think about it the same turbo car at sea level is going to make a lot more power with the better air. The turbo just wont have to work that hard.

My car runs 14.1@95mph with nhra alltitude correction I would run a 13.5.

If you like it or not I dont care alltitude affects FI cars just as much as other cars.

 

[laserspeeddemon]

I was just trying to make point of views.

You're right a turbo would have to work harder, meaning you would have to turn up the boost to another setting to acheive the same boost at lower elevation.

 

[FINETUNED]

I have found that I can run 14-16 psi at 3200ft. When i go to the city to race (2000ft) I can run 2-3psi more how do ya figure that?

 

[hostile]

That makes since because at the higher eleviation the turbo will be in a different effecincy range.

 

[laserspeeddemon]

Originally posted by hostile
That makes since because at the higher eleviation the turbo will be in a different effecincy range.

agreed.

 

[mxracer]

Also boost gauges read in absolute pressure. Meaning at sea level you are at 29.92" of merc. but your boost gauge may read 0psi but at 6k' the baro could be like 27.92" of merc. and the boost gauge would still read at 0psi. This means you are really losing density but you wouldn't be able to tell with the boost gauge becuase it takes two values, 1 from the psi in the ic piping and 2nd from the outside barometric pressure. This is how you run 2-3 psi more at a lower altitude.
Hopefully this makes some sense.

 

[laserspeeddemon]

Originally posted by mxracer
Also boost gauges read in absolute pressure. Meaning at sea level you are at 29.92" of merc. but your boost gauge may read 0psi but at 6k' the baro could be like 27.92" of merc. and the boost gauge would still read at 0psi. This means you are really losing density but you wouldn't be able to tell with the boost gauge becuase it takes two values, 1 from the psi in the ic piping and 2nd from the outside barometric pressure. This is how you run 2-3 psi more at a lower altitude.
Hopefully this makes some sense.

Uh, what?

 

[Stock Josh]

I understood him....................

 

[Defiant]

Originally posted by laserspeeddemon

You're right a turbo would have to work harder, meaning you would have to turn up the boost to another setting to acheive the same boost at lower elevation.

I'm curious about some of this. At elevation, the air's thinner. Fewer molecules per volume. So the turbocharger's got fewer grains of air to pump, which means it has less load on it, which should mean more free to spin. Which would mean higher speed, which would mean _more_ volume is pumped..... would that compensate for the lower density?

I don't drag, but I don't _feel_ a power loss in my Talon when at Tahoe or Bodie at 6-8,000 ASL compared to glorious Galt's 15 feet.

Of course, in an Eagle, you don't want to get to too high an altitude, because you'll get too close to the sun and it'll melt the wax that holds the feathers in your wings.

 

[pneumo]

I've driven up to Tahoe many times. Up there when the turbo kicks in it feels just a little weaker. But is sure does take longer to spool up, and off boost power is definately down.

Is glorious Galt somewhere on the way to Tahoe? I don't remember seeing Galt, but I do remember some cows standing around a watering trough. Was that Galt?

 

[Stock Josh]

Dude, that was so funny..............................

 

[hostile]

Also remember the higher you go the cooler the air gets. So alltitude isn't always a factor in which car runs better.

My car would run slower at 3000 feet and 100 degrees than another guys car at 5000 feet and 50 degrees.

Density Alltitude is affected by temp, humidity, and elevation.

 

[mxracer]

Density altitude is not affected by humidity. Although humidity does adversely affect performance. Just for shits and giggles the density altitude for 3k' and 100 degrees is 6100' and for 5k' and 50 degrees its 5900' that shows how Arizona can be just as shitty as in Denver

 

[hostile]

Well you need a dew point to do density calculations? Maybe I am thinking of relative density of air. My friend did the comparison and the air was like 5% less dense here than denver at the same point in time.

Some guys on another board ganged up on me and told me I was an idiot when I said west texas would be worse than colorado.