1/4 mile times

[ebny]

Is 13.8 seconds considered fast for the 1/4 mile?

[rage2]

depends on the car and the person you're talking to :).

[davidI]

I'd consider that fast but once again it depends on the car and how much money is going into it. Considering a lot of people with imports on this board are 15+ (I'm one of these people) I'd consider 13's and lower to start being fast for a 'grocery getter'

[Akagi Redsuns]

For me, below 14 is pretty fast as I part of the common folk with average cars. If I was a high roller...its slow :). What's the trap speed? Above 100MPH?

[Nix87]

aha i dont even wanna think bout my 1/4 Mile time. Take the land yacht days to get down the track.

Nick

[ebny]

02 WRX - That was my time last year.....running 16 lbs of boost. on the stock turbo yadda yadda yadda.....i have read in subaru forums that down in the U.S. WRX's with about the same mods as mine they are running low 13s. Is it because of the altitude down there or sumthin? I tried so hard to get in low 13s....dunno wtf im doing wrong...although i havnt tried any weight reduction other than removing my spare tire.....but lets say i did strip my car down would it cut .5 of a sec on my times??

[1-Bar]

Yeah altitude.....Calgary way up there=less dense air therefore less power especially for FI cars. Better stickies would help a lot on the track....

[CRX-R]

you'll only lose APPROX.... 0.1 for every hundred pounds, but this is definately only an estimate

[ebny]

Originally posted by 1-Bar
Better stickies would help a lot on the track....



Well im on Pirelli P7000......considering i dont even peel out on my launches!.......AWD BABY!!!! :D :D


:burnout: <------THATS A NO! NO!

[rage2]

It's an altitude issue. Your turbo is beginning to work out of it's efficiency range when you crank up the boost.

[ebny]

Originally posted by CRX-R
you'll only lose APPROX.... 0.1 for every hundred pounds, but this is definately only an estimate

Well i ran the 13.8 on a full tank of gas too......being about 50 liters....would that be about 100 pound of useless weight? I dont wanna do the calculations.....

lol....how many pounds are in a liter....????:nut: :nut:

[ebny]

Originally posted by rage2
It's an altitude issue. Your turbo is beginning to work out of it's efficiency range when you crank up the boost.


so ur saying if i did run down south i would be in the low 13s???

[davidI]

Originally posted by ebny


Well i ran the 13.8 on a full tank of gas too......being about 50 liters....would that be about 100 pound of useless weight? I dont wanna do the calculations.....

lol....how many pounds are in a liter....????:nut: :nut:

If I remember correctly a liter is a kg (of water atleast) and there are 2.2 pounds in a kg so you'd have around 110 pounds of useless weight in there.

[1-Bar]

Correct me if I'm wrong. But when you crank the boost up on a stock system your running the turbo harder and therefore a lot hotter. Not a good idea because heat increase leads to efficiency decrease....Sure you may be at XXPSI but the efficiency rating of the turbo is way below normal which is ~60-70% a lot higher if you have an IC.

[HOK]

it depends on the correction factor for that day... race city sometimes will tell you the elevation...

i would say yes you are mid 13 and maybe low 13 on good days at sea level... but corrected times are never accepted by people at sea level.... but they also never want to run at our altitude... hehe go figure... what was your entire slip.. ie 60ft, mph etc...

I ran a 13.4 1.9 at 101 mph...

[ebny]

Originally posted by davidI


If I remember correctly a liter is a kg (of water atleast) and there are 2.2 pounds in a kg so you'd have around 110 pounds of useless weight in there.


Thanks DavidI...........so my time would drop to 13.7 hopefully 13.6....gotta try that ......

see yall at the track!!!!!:burnout:

[ebny]

Originally posted by 1-Bar
Sure you may be at XXPSI but the efficiency rating of the turbo is way below normal which is ~60-70% a lot higher if you have an IC.


~60-70% higher than what? R U saying that if i have a IC (which i do), then the efficiency of by turbo will be 60-70% less efficient...? I dont understand whut u mean here......anyone explain pleeeze! (if you understand)?

[ebny]

Originally posted by HOK
it depends on the correction factor for that day... race city sometimes will tell you the elevation...

i would say yes you are mid 13 and maybe low 13 on good days at sea level... but corrected times are never accepted by people at sea level.... but they also never want to run at our altitude... hehe go figure... what was your entire slip.. ie 60ft, mph etc...

I ran a 13.4 1.9 at 101 mph...



WOW HOK! thats GOOD!!!!:bigpimp:

ill have to go home to get my slip....ill post later...after work! BTW whats done to ur soob? And is it you that won 1st place too at ISO. Congrats! if it was.......

[Khyron]

Ok - Altitude affects NA cars cause the air is thinner/less dense/whatever.

Explain how a Turbo car would be affected by this MORE than an NA car. It should be much less - a turbo compresses air to a set PSI. If air compressed to 15 PSI at sea level, that's the same thing as if you compressed it to 15 PSI here (you'd use more tho because of the density). But the end result is a fixed measurement - 15 pounds per square inch of pressure.

Anyone with authority on the subject?

Khyron

[HOK]

no... who said turbo cars get more affected by altitude... generally speaking at our altitude we are 2 psi less... ie 15 psi at sea level is about 17 here.... pressure isn't always pressure either.... absolute pressure is different up here then down at sea....


also its always about flow... and how much air you can move.. not just psi...

[HOK]

Originally posted by ebny




WOW HOK! thats GOOD!!!!:bigpimp:

ill have to go home to get my slip....ill post later...after work! BTW whats done to ur soob? And is it you that won 1st place too at ISO. Congrats! if it was.......

heheh thanks! thanks that was me... btw whats done to your car... heh i don't think you have the stock turbo...;)

[rage2]

Originally posted by Khyron
Explain how a Turbo car would be affected by this MORE than an NA car. It should be much less - a turbo compresses air to a set PSI. If air compressed to 15 PSI at sea level, that's the same thing as if you compressed it to 15 PSI here (you'd use more tho because of the density). But the end result is a fixed measurement - 15 pounds per square inch of pressure.
It all depends on how boost is regulated in the stock setup, as well as how much additional capacity the turbo is capable of (which side of the efficiency map it currently sits on).

In *most* turbocharged applications, the boost control system regulates boost to a set psi referenced to current atmospheric pressure. So at sea level (14.7psi), the car boosts to 10psi, the total pressure would be 24.7psi. In Calgary, where ambient absolute pressure is in the 13psi range, the same car would have 23psi, a loss of 6.88%. A NA car would see 14.7psi pressure at sea level, 13psi here, so a loss of 11.56%. In this instance, the turbo car loses less power than a NA car.

On some cars, boost is regulated based on absolute pressure, so the turbo will keep spooling up until it hits a set manifold pressure of 24.7psi (assuming 10psi boost). In this case, there is very little loss of power, the only loss coming from different efficiency of the turbo compressing more air to achieve the same pressure. Depending on the turbo size (ie turbo is too big), it could be more efficient at higher altitude, making MORE power up here. But that's rare :).

Now, if you have a turbo that's sized really small to reduce turbo lag (ie most stock setups), and you use a boost controller to crank up the boost so the pressureis equivilent to what it would be at sea level, you would assume that it would make the same power as sea level. Wrong... because as you speed up the turbo more to create the additional boost, the compressor falls well off it's efficiency map, so at the higher pressure, temps go up, densitiy goes down. In some cases, the additional 2psi of pressure creates a charge so hot, it'll have less density than at the original boost level. Intercooler's not going to fix that, because the air density is reduced at the outlet of the compressor before the IC, the IC just lower temps, doesn't create additional oxygen molecules. So in the end, you gain nothing by cranking the boost up.

Finally, to answer the original question, a turbo car does NOT get affected more by altitude... either the same as NA, or less depending on configuration and turbo sizes. Look at the NHRA correction for NA vs turbo cars, and you'll see that turbo cars are affected less.

BTW kenny, search on google, betcha this post aint there! :rofl:

[1-Bar]

Originally posted by ebny



~60-70% higher than what? R U saying that if i have a IC (which i do), then the efficiency of by turbo will be 60-70% less efficient...? I dont understand whut u mean here......anyone explain pleeeze! (if you understand)?


Sorry, that explanation is confusing. Most turbos run at an efficiency rating at ~60-70%. If you get a IC added to your turbo setup it increases the rating to close to 80% given you picked the right size....This efficiency drops significantly if you boost too high which causes the compressor to put more heat into the intake charge and also adds more exhaust manifold back pressure increasing the heat load.

Hope that helps.

[ebny]

Understood!...thx..

Anyways....I never knew you can run a turbo setup without and intercooler......

[kenny]

Originally posted by rage2

Finally, to answer the original question, a turbo car does NOT get affected more by altitude... either the same as NA, or less depending on configuration and turbo sizes. Look at the NHRA correction for NA vs turbo cars, and you'll see that turbo cars are affected less.

BTW kenny, search on google, betcha this post aint there! :rofl:

Its not on google, because that is incorrect. Turbo cars are affected more by altitude, go talk to your mechanic :thumbsup:

[rage2]

You can, but you'll boost a lot lower than if you had an intercooler.

[rage2]

Originally posted by kenny
Its not on google, because that is incorrect. Turbo cars are affected more by altitude, go talk to your mechanic :thumbsup:
haha LIAR! :)

[Khyron]

Originally posted by rage2

It all depends on how boost is regulated in the stock setup, as well as how much additional capacity the turbo is capable of ...
Finally, to answer the original question, a turbo car does NOT get affected more by altitude... either the same as NA, or less depending on configuration and turbo sizes. Look at the NHRA correction for NA vs turbo cars, and you'll see that turbo cars are affected less.

BTW kenny, search on google, betcha this post aint there! :rofl:

Now THAT is a good answer. I always assumed that all turbo cars were regulated by absolute manifold pressure (thus altitiude having little or no effect). Why are all turbos not regulated as such seeing as there's such variance on altitude? How do you tell which cars are managed like this?

I also never considered the heat factor of the turbo (a turbo spinning 15 PSI at sea level will be generating less work/heat that one spinning the same PSI at 6000 feet) - makes sense.

Khyron

[Wrath]

Originally posted by ebny
Is 13.8 seconds considered fast for the 1/4 mile?

www.members.shaw.ca/albertastreetcarstats

There are a a few cars to compare yourself to

[HOK]

Originally posted by Wrath


www.members.shaw.ca/albertastreetcarstats

There are a a few cars to compare yourself to

Rage rage2 03 SLK 32 AMG 13.11 107.60 Calgary Stock (supercharged) + Air Fliter


YEAAAAA SUUUUUUUURE

[Z_Fan]

Originally posted by rage2

Now, if you have a turbo that's sized really small to reduce turbo lag (ie most stock setups), and you use a boost controller to crank up the boost so the pressureis equivilent to what it would be at sea level, you would assume that it would make the same power as sea level. Wrong... because as you speed up the turbo more to create the additional boost, the compressor falls well off it's efficiency map, so at the higher pressure, temps go up, densitiy goes down. In some cases, the additional 2psi of pressure creates a charge so hot, it'll have less density than at the original boost level. Intercooler's not going to fix that, because the air density is reduced at the outlet of the compressor before the IC, the IC just lower temps, doesn't create additional oxygen molecules. So in the end, you gain nothing by cranking the boost up.


This is absolutely true. Besides all the sh!t I don't understand, I can definitely vouch for the fact that additional boost, or cranking the boost, doesn't do a damn thing.

You might be surprised, but I can set my boost a 13.5psi and run a 13.5 - 13.7 1/4 mile. Now, I can then turn around and set it to 17psi and wind up running a 13.8.

The other thing that is for certain (at least in my car) is that the first two runs will be the only 'fast' ones. After that, everything is hot, and it's just less efficient.