I guess I'll agree with most of that. 15 psi gauge is 15 psi gauge regardless of altitude, but it's not the same in absolute pressure at different altitudes. I crunched some made up numbers.... say at sea level, ambient pressure is 15 psi (1 atm = 14.7psi). So 15psi ambient plus 15 psi gauge = 30 psi absolute. At altitude, say the ambient pressure is 13.5 psi, plus 15 boost = 28.5 psi absolute. So the absolute pressure is lower at altitude.
But the pressure ratio changes too. So at sea level, it'd be (15+15)/15 = 2. At altitude, (13.5+15)/13.5 = 2.11 (I think I calculated PR correctly... off the top of the head). So the turbo is operating at a higher pressure ratio at altitude so I guess that makes up for some of the difference in mass flow rate due to the lower absolute pressure. But operating at the higher pressure ratio also heats up the air more, so you'll lose some efficiency/power there.
So my guess is, if the turbo is operating well within its max efficiency island on the compressor map at sea level, then there won't be a lot of difference at altitude, but I think the mass flow rate at altitude will still be a tad lower than see level due to the higher pressure ratio. If you're already at the edge of the good efficiency islands, you'll probably lose a fair amount of power like you said.
So...uh... anyone want to drive from LA to Denver and test it out?
My answer to that pretty well though out argument is: Don't forget there is 15 psi IN the manifold. That pretty much negates the lack of ambient pressure. That means the turbo is actually pushing maybe 16 psi worth of air , but actually due to altitude ambient pressure losses making a self corrected 15 psi , on the guage. And if nothing else , MAF flow at this altitude will be the same as sea level , as the turbo strives to maintain 15 psi with less overall air mass to work with. That's what I meant about the turbo spinning faster to overcome the lesser air pressure and mass at this altitude.
__________________
1992 Yamaha FZR 1000. 145 Hp, all stock..
Some of you guys are not telling the truth, TruBluZ and JAMESZ.
Wow, that's nice. Since you have obviously not seen me run, you assume I am not telling the truth. Ok, if you say so. There were only about 75-100 people that witnessed my run. I could post the slip, but you could easily say that it wasn't my slip. Go to the track someday. I know at least 3 other stock Zs that are in the 13s. Here's one for you....a stock auto Z in the 13s. But again, I must be lying, because the mags say that it is impossible.
Wow, that's nice. Since you have obviously not seen me run, you assume I am not telling the truth. Ok, if you say so. There were only about 75-100 people that witnessed my run. I could post the slip, but you could easily say that it wasn't my slip. Go to the track someday. I know at least 3 other stock Zs that are in the 13s. Here's one for you....a stock auto Z in the 13s. But again, I must be lying, because the mags say that it is impossible.
Just post your time slip and I will know if your telling the truth?
getting below a 14.3 is deffinatly possible, and i wouldn't be pressed to believe a sub 14 run to be possible on a well prepped track. I know ya'll are gonna call b.s. on this but there are 2002-2003 maximas running 14.3 and lower stock. And they are fwd and only have 255 bhp. but they are slightly ligther i believe. If you want to see time slips check maxima.orgs 1/4 forum. Although it is down for the moment. and about the magazine times. You've got to remember that while i'm sure these guys are good drivers, every car takes getting used to and has its own launching techniques. so these numbers can quite frequently be beaten. One such case is the 2000 maxima, one of the magazines claims a 15.7 on this car. Everyone and there mother can beat that time in a stock 5 speed 2000 max. there have been claims at 14.8, and 15 is pretty regular
The Injen CAI robs horsepower???? Why would anyone put it on the car if it doesn't make gains? I have an auto, and the AEM CAI I installed seemed to make a difference. What would make the cold air intake take away power? Sorry for the noob question.
Just wanted to add I have an SE-R, not a Z. Just interested in knowing if the CAI robs horsepower in general or if its just not a good mod to do to a Z.
this is off topic but i have seen a dyno of a injen intake and at one point it may lose 1-2 hp but it gains 4-5tq elsewhere. Its all about gains across the board.
but as for the z33's running in the 13's i can belive it. it someone can pull off a low 14sec time then wit some slicks or dr's or some insanly good high performance sticky tires, they should be able to nail a great 60' along wit a great reaction time then 13's should be in reach. hell we have a guy wit a a32 maxima who runs 14.1 on a bad clutch, if he can do that time wit almost 40 less hp then y is it impossible for a rwd 240whp car wit more tourque?
my brother beat a 350z - supercharged. with his nx2000. my brother smoked him bad, he runs 13.2 without nos, 12.3 with. this was at a 1/4 mile track without the tree, he said he hardly used the sqeeze...so they cant be that fast. but very sweet looking
__________________
please check out our sites: www.nissansofspokane.nismo.org , www.cardomain.com/id/aggrivator , www.cardomain.com/id/nx2kdet , www.cardomain.com/id/smokinnx , www.cardomain.com/id/doidrag , MY CAR: 98 SE-R - T3, JWT ECU, S3, POP, CUSTOM INTAKE & EXHAUST..AND THAT IS JUST THE START OF THIS LONG LIST
quote:
Originally Posted by TruBluZ
Wow, that's nice. Since you have obviously not seen me run, you assume I am not telling the truth. Ok, if you say so. There were only about 75-100 people that witnessed my run. I could post the slip, but you could easily say that it wasn't my slip. Go to the track someday. I know at least 3 other stock Zs that are in the 13s. Here's one for you....a stock auto Z in the 13s. But again, I must be lying, because the mags say that it is impossible.
Quote:
Originally Posted by Spongerider
Just post your time slip and I will know if your telling the truth?
All I asked was a time slip of the run, twiceTruBluZ could not produce. Another one shot down!
you must remember that people all over the nation will be getting different times B\C of different altitudes, humidity, track conditions, etc.. I have seen one run a 13.9, and another with only BPU's (hedders, full exhaust, pulleys i believe, intake, and mabe a few other here and there's) run one carlength behind a low 12 second audi S4 (going from a roll). He took me by a carlength from a dig when I was BPU, and I was going 13.2-13.3. I hope to see him with this new setup.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Linear Mode
