NA cars and our 1/4 mile tracks

[mugenmclude]

http://www.albeedigital.com/supercoupe/articles/0-60times.html

Seems like na cars run 1 sec slower on our 1/4 tracks.what are owners of rsx s owners running 15.8-16.00

I'm liking them now but seems like a lost cause to try to run 14.8 stock @ castrol

[Mr_ET]

yeah pretty much

[Toms-SC]

Various degrees of slow.

For a stock car I feel your predictions are about right. :dunno: Really did not see any running last season at RC.

[Speedy]

Compared to what other tests?? Other tracks??

Just a shot in the dark here but what affect does the altitude have here on car racing? being we are 3500ft above sea level, I know I used to notice a difference in my car when I took it down to sea level.

The air is way less dense up here and there for more air is required and I can see NA's noticing it more. that has to play a big factor in times

[mugenmclude]

Mags,tv shows,also have 2 charts of 1/4 mile tests

[alloroc]

Originally posted by mugenmclude
http://www.albeedigital.com/supercoupe/articles/0-60times.html

Seems like na cars run 1 sec slower on our 1/4 tracks.what are owners of rsx s owners running 15.8-16.00

Link above of 1 1/4 mile chart

Well ... ya of course.


Altitude has already been mentioned. Traction is also a factor, the Southern US tracks never see winter and are maintained better.

[Aleks]

Lesson from all this?

Don't buy NA cars in Calgary :poosie:

[mugenmclude]

Are stock f/I cars running stock advertised times?

[alloroc]

Originally posted by mugenmclude
Are stock f/I cars running stock advertised times?

F/I narrows the gap but they are closer but still slightly slower than advertised - especially at race city.

[Mr_ET]

Originally posted by mugenmclude
Are stock f/I cars running stock advertised times?

they aslo run slower lol. The altitude and traction at our track are far from optimal.

Castrol raceway is usually about 0.4 to 0.5 seconds faster and 2-3 mph more for the same setup.

I have seen many SI's run 16.5 here but I think most of it is the driver and very few are good enough to extract everything the car has to give.

I took 2 different cars out for one pass each last year, had never driven them before and beat the owner's personal bests so it's really more about driver than track an altitude.

Whatever you have it can probably do better with a bit more practice!

[LilDrunkenSmurf]

Originally posted by Mr_ET
I took 2 different cars out for one pass each last year, had never driven them before and beat the owner's personal bests so it's really more about driver than track an altitude.


Awe, go ahead and make me feel good about myself.

+1 he beat my personal best in my own car by .2 seconds on his first and only attempt in it.

[mugenmclude]

.

[Cody D]

Okay, I'll try this.

Sea level is 14.7psi, the higher altitude you go the less pressure there is in the atmosphere. The less pressure means the air is less dense which lowers power. You can figure out how much by doing the math. If our pressure here is 13 psi (I didn't actually look it up) then you are running 88.4% less air pressure (13 divided by 14.7) than you would at sea level. I don't know if that means that you are running 88.4% of your power but it is less power.

With a forced induction vehicle you are changing the pressure of the air going into the engine, so if you are using 10psi boost you are putting 23psi into the engine if normal atmosphere at your elevation is 13psi. So that changes the percentage of power loss (23 divided by 14.7). 156% more air pressure than normal atmosphere.

I'm sure the smart people are going to tear this apart, haha.

[benyl]

Originally posted by Aleks
Lesson from all this?

Don't buy NA cars in Calgary :poosie:

:werd:

With FI cars, it all depends on if they are MAF based or MAP based.

MAP based cars will make the same power here as they do at sea level. MAF, not so much.

[Cody D]

Originally posted by benyl
MAP based cars will make the same power here as they do at sea level. MAF, not so much.

Won't it always be less here at the same boost level as sea level?

[lhatton]

is the track prep at racecity really that bad?

I just moved here from abbotsford and mission raceway is at 22 feet altitude i believe. I know altitude plays a huge factor in NA power but I don't know exactly how much. I am rusty at the track as i didn't race at all last year, but i am going to try out my car this summer at racecity and compare. I bet .3-.4 slower and 2-3 mph different.
Any educated guesses?

[redline]

Originally posted by Cody D


Won't it always be less here at the same boost level as sea level?

yes

[mugenmclude]

:burnout:

[banned3x]

i have a charger r/t and people are hitting 14.5 stock down in the states and every pass i did in race city was 15.5-15.4 secs

[Darkane]

Depends on the driver.

I hit 15.7 with my FG2, with a 2.43 (awful I know) 60ft. I could do 15.3ish with a 2.2

Sorath ran a 15.2 with his Si though.

[Mr_ET]

Originally posted by LilDrunkenSmurf


Awe, go ahead and make me feel good about myself.

+1 he beat my personal best in my own car by .2 seconds on his first and only attempt in it.

Haha sorry buddy she ran pretty good though :)

[epp01]

I think it also has something to do with racecity's timing system my talon only ran a 13.4 at race city but did a 12.6 in castrol.

[mugenmclude]

was Sorath si 100% stock?

[Mibz]

Originally posted by redline
yes No. Absolute pressure is absolute pressure. 1 BAR at sea level = 1 BAR at 3500 feet. The density of the air is the same. MAP based sensors will be the same across elevations, MAF will not.


Originally posted by epp01
I think it also has something to do with racecity's timing system my talon only ran a 13.4 at race city but did a 12.6 in castrol. While I'm not denying the lack of quality in the timing equipment, Castrol tends to be a much better prepped track. What were your 60' for those two runs?

[Cody D]

Originally posted by Mibz
No. Absolute pressure is absolute pressure. 1 BAR at sea level = 1 BAR at 3500 feet. The density of the air is the same. MAP based sensors will be the same across elevations, MAF will not.

I don't understand this, yes 1 BAR is 1 BAR, but if your turbo is putting in 10 PSI and atmosphere is only 13 PSI then you will get less power than if you were running 10 PSI at 14.7 PSI. In one engine you will be running 23 PSI and in another you will be running 24.7 PSI. The fact that the air flow meter is reading flow or pressure shouldn't change that fact.

[Mr_ET]

Originally posted by Mibz
No. Absolute pressure is absolute pressure. 1 BAR at sea level = 1 BAR at 3500 feet. The density of the air is the same. MAP based sensors will be the same across elevations, MAF will not.


I am sorry but that is incorrect in the real world regardless of MAP, MAF N/A or F/I. I have seen any type of car run slower here vs at Sea Level because of the elevation.

I know I'm from Quebec city that has a track at like 3ft above sea level or something with eaqually as shitty track prep and all cars are at least .5 seconds faster with the exact same setup.

[Aleks]

From my experience at Race City I have been able to get very close # to what the magazines show for stock on two of my cars.

2006 WRX stock I ran 14.2 and 2008 GTI I hit 14.7 stock.

I know in mags the Si and GTI are always about the same ET wise but it's not very close up here so the turbo helps offset the altitude issues.

[Revhard]

They aren't that bad. I ran a 15.7 here with just an intake when I was a complete rookie. Most people just don't want to drive it hard enough to be fast. Very similar to the awd crowd.
If you are scared to break things, you aren't going to be fast.
This track sucks, for sure. You can still go and have a good time ripping off decent times.
My rsx ran 13.5 on a decent night, not a "ringer" night.
I have some good mods, but that was all Honda parts except bolt-ons and slicks. I was running low 14's with street tires(14.1) and mediocre mods that were very affordable.

Forced induction is for sure the easy way out around here, but you still have to know how to drive. You can see that just as plainly when you go to the track.
A few of the right parts go a long way around here. Tires are a big one.

Also, the air density is different with elevation, the volume stays the same. Otherwise, go parade up everest without an oxygen mask and see how you do.
Turbo cars see a much smaller difference in the density when you are compressing it. The local dyno's don't account for this though, so the dyno numbers are always skewed, making the track times look even worse.

[Ekliptix]

Here noobs: http://www.iroc-zpostforum.com/NHRACF.htm
Note that although it says Elevation, you should really use the density altitude (DA) during the time of your run.

Btw, I run 12.18 at 116.5 NA, uncorrected. :poosie:

[alloroc]

Originally posted by Cody D


I don't understand this, yes 1 BAR is 1 BAR, but if your turbo is putting in 10 PSI and atmosphere is only 13 PSI then you will get less power than if you were running 10 PSI at 14.7 PSI. In one engine you will be running 23 PSI and in another you will be running 24.7 PSI. The fact that the air flow meter is reading flow or pressure shouldn't change that fact.

Yes and no it is all about compressor curves and fan laws.

Alt. affects turbo cars as they spool and it affects blown engines through the whole range, blown engines can compensate in the top end a change in the gear ratio. However at full boost using a spring controlled wastegate your boost is PSIG and not PSIA and you should make **near the same power at high alt as compared to low alt (within reason, I am talking cars not airplanes) ... unless your turbo is 'just big enough' at low alt to keep up and it falls behind at high alt.

**All that said, turbo efficiency and heat also play a factor running at higher altitudes means the air has to get compressed more from whatever the atmospheric conditions are to the gauge pressure. The extra heat and work the turbo does is the reason for the small loss of power compared to sea level. The drop however is quite negligable when compared to normally aspirated engines.

http://www.sportcompactcarweb.com/editors/technobabble/9907scc_technobabble/index.html


Corrected numbers, on the other hand, can be suspect in certain cases as well. Turbocharged cars running at high altitude, for example, might be more accurately represented by uncorrected numbers. Say you are testing an FD3S RX-7 in Denver, where the elevation is approximately 5,000 feet. Shiv Pathak, master of our FD3S RX-7 project, reports that he always sees higher boost levels at high altitude. The reason is simple. The wastegate opens when boost is 12 psi higher than the normal sea-level reference air behind the wastegate actuator diaphragm (air that has been stuck in there ever since the diaphragm was sealed somewhere in Hiroshima). As the air density drops at high altitude, the actual pressure in the boosted intake manifold remains constant. The boost gauge, though, reads pounds of boost over ambient pressure. If the ambient air pressure in Hiroshima was 14.5 psi when that diaphragm was sealed, but it is only 13.5 psi when Shiv drives through the mountains, his boost gauge will read 1 psi higher than normal.

[alloroc]

Originally posted by Aleks
From my experience at Race City I have been able to get very close # to what the magazines show for stock on two of my cars.

2006 WRX stock I ran 14.2 and 2008 GTI I hit 14.7 stock.

I know in mags the Si and GTI are always about the same ET wise but it's not very close up here so the turbo helps offset the altitude issues.

case in point,
Turbo -nearly offsets the altitude change and the AWD helps reduce the race city traction problem.

[Mibz]

Originally posted by Cody D
I don't understand this, yes 1 BAR is 1 BAR, but if your turbo is putting in 10 PSI and atmosphere is only 13 PSI then you will get less power than if you were running 10 PSI at 14.7 PSI. In one engine you will be running 23 PSI and in another you will be running 24.7 PSI. The fact that the air flow meter is reading flow or pressure shouldn't change that fact. It doesn't matter what the pressure in the atmosphere is, just what the pressure in your manifold is. As far as I know, all other things being equal, air density is consistent with pressure. 24psi of high altitude air is just as dense and just as oxygenated as 24psi of low altitude air. This seems to be the point of contention though, so I may be wrong, but nobody has really proven it yet.


Originally posted by Mr_ET
I am sorry but that is incorrect in the real world regardless of MAP, MAF N/A or F/I. I have seen any type of car run slower here vs at Sea Level because of the elevation. I'm willing to accept that I'm wrong, but not because you've seen cars run slower. If you've got some science to back it up then I'd like to hear it.

[Darkane]

Originally posted by mugenmclude
was Sorath si 100% stock?

Yes and a 4 door to boot. He just took out the spare If I recall.

[gretz]

Originally posted by Mibz

I'm willing to accept that I'm wrong, but not because you've seen cars run slower. If you've got some science to back it up then I'd like to hear it.

Science? i'll do you one better - take my carb'd crx to the mountains and let me know what you think.

I think (don't quote me) the thin air is messing up the A/F ratios, less dense air = running more rich = slower

[Eleanor]

Originally posted by Mibz
It doesn't matter what the pressure in the atmosphere is, just what the pressure in your manifold is.
True, but the your manifold pressure reading is still gauge, not absolute AFAIK.

[Darkane]

I tried to figure out actual losses of Forced cars at our altitude from one of my texts.

I almost did, or thought I did lol.

But cliff notes were forced gauge pressure would always be the same regardless of altitude. The waste gate would open the same.

The difference in absolute with us being like 13.9psi vs 14.7 @ sea level would only be on top of the forced pressure.

10psi example = 24.7 absolute vs 23.9 absolute for us here.

The difference becomes quite smaller. I was actually calculating HP figures and got quite messed up lol. It's not just an easy ratio calculation :)

[Mibz]

Originally posted by Eleanor

True, but the your manifold pressure reading is still gauge, not absolute AFAIK. I assume it would depend on the sensor. I'll admit I have -no- idea how MAP sensors usually work but if they are calibrated at 1 BAR then your overall reading, no matter what your altitude will be correct.

[texasnick]

Originally posted by Darkane
I tried to figure out actual losses of Forced cars at our altitude from one of my texts.

I almost did, or thought I did lol.

But cliff notes were forced gauge pressure would always be the same regardless of altitude. The waste gate would open the same.

The difference in absolute with us being like 13.9psi vs 14.7 @ sea level would only be on top of the forced pressure.

10psi example = 24.7 absolute vs 23.9 absolute for us here.

The difference becomes quite smaller. I was actually calculating HP figures and got quite messed up lol. It's not just an easy ratio calculation :)

This is the best explanation. I think you guys are getting the concepts of absolute/guage pressure confused.

It's simple. The higher in elevation you go, the lense dense the air. The less dense the air, the less ABSOLUTE pressure your motor is intaking.

F/I cars minimize this power loss by raising the % ABSOLUTE pressure difference when compared with lower elevations. But, there WILL BE LESS ABSOLUTE OXYGEN PRESSURE going into the intake manifold regardless of induction type.

In mines in Chile (high elevation) the only support equipment that you ARE ABLE to run are turbo-diesels. All non F/I diesels will choke for air and not work.

[Mibz]

Originally posted by texasnick


This is the best explanation. I think you guys are getting the concepts of absolute/guage pressure confused.

It's simple. The higher in elevation you go, the lense dense the air. The less dense the air, the less ABSOLUTE pressure your motor is intaking.

F/I cars minimize this power loss by raising the % ABSOLUTE pressure difference when compared with lower elevations. But, there WILL BE LESS ABSOLUTE OXYGEN PRESSURE going into the intake manifold regardless of induction type.

In mines in Chile (high elevation) the only support equipment that you ARE ABLE to run are turbo-diesels. All non F/I diesels will choke for air and not work. See, this doesn't make sense to me. Ignoring a gauge completely, if there is 20psi of absolute pressure in my manifold at 3500ft, how is it any different from 20psi of absolute pressure at 0ft?

[Darkane]

Originally posted by Mibz
See, this doesn't make sense to me. Ignoring a gauge completely, if there is 20psi of absolute pressure in my manifold at 3500ft, how is it any different from 20psi of absolute pressure at 0ft?

It isn't.

However, that simply means you're running about 0.8psi LESS boost pressure at 0 feet.

[alloroc]

Originally posted by Darkane


It isn't.

However, that simply means you're running about 0.8psi LESS boost pressure at 0 feet.

The waste gate though is psig and spring controlled, so even though a psia gauge calibrated here reads 0.8 psi less at sea level, the manifold sees the same pressure.

As I stated above the slight loss of turbos (max power) at altitude is because of efficiency loss and the increased heat of compression. While spooling however the altitude plays a much larger factor.

That said .. the power loss compared to N/A cars at altitude is negligible. Dyno shops are not supposed to apply density corrections to turbo cars.

[texasnick]

Originally posted by Mibz
See, this doesn't make sense to me. Ignoring a gauge completely, if there is 20psi of absolute pressure in my manifold at 3500ft, how is it any different from 20psi of absolute pressure at 0ft?

Your boost guage isn't reading absolute pressure. It is reading guage pressure.

[Mibz]

Originally posted by texasnick


Your boost guage isn't reading absolute pressure. It is reading guage pressure. My boost gauge doesn't tell my computer how much pressure there is, my MAP sensor does, and that's why I'm trying to figure out how a MAP sensor works. I was under the assumption that it would read absolute pressure.

[alloroc]

Originally posted by Mibz
My boost gauge doesn't tell my computer how much pressure there is, my MAP sensor does, and that's why I'm trying to figure out how a MAP sensor works. I was under the assumption that it would read absolute pressure.

Depends if the gauge is purely an electromechanical spring type -psig. Or it could be a crytal piezometer -psig or it could be an electomechanical spring and diaphram psia.

Most modern map sensors are crystal peizometers.

[Mibz]

Originally posted by alloroc


Depends if the gauge is purely an electromechanical spring type -psig. Or it could be a crytal piezometer -psig or it could be an electomechanical spring and diaphram psia.

Most modern map sensors are crystal peizometers. If they're piezoelectric then they'll read absolute pressure. Cool.


As I stated above the slight loss of turbos (max power) at altitude is because of efficiency loss and the increased heat of compression. While spooling however the altitude plays a much larger factor.I'm so sorry I missed this. -This- makes perfect sense to me. There's no difference in the air, it's that the turbo has to work harder to make the same boost.

[gretz]

Makes sense, my buddies diesel can only run 45lbs here, in ontario he runs 51lbs without any changes

[alloroc]

Originally posted by gretz
Makes sense, my buddies diesel can only run 45lbs here, in ontario he runs 51lbs without any changes

That is a big change and is opposite of the readings most people get, my guess is his turbo is running at it's limit.

[Eleanor]

Originally posted by alloroc
Most modern map sensors are crystal peizometers.
Do you know what they're calibrated to? 101.325kPa?