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Old 09-15-2003, 11:18 PM   #51
Zen
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I think there would be more turbulence since there is more surface area in the back. Just a guess..
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Old 09-16-2003, 12:59 AM   #52
Hawk296
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about decreasing drag.... differnt spoiler.. front spoiler.. those do not decrease drag. Those would increase drag. It might increase downforce making thecar handle better at speed but top speed woudl decrease and drag would increase.

A spoiler itself just gets in teh way and disrupts airflow creating turbulence/drag killing lift. A wing on a car is like an inverted airfoil kinda in the fact that it pushes down instead of up like in a plane. This also produces both a parasitic drag and a kind of induced drag.

To decrease drag... hmmm. The front end can definatly be cleand up a lot. and something needs to be done with the rear. If you notice when its raining the lower half of the window, the water actually flows up at speed instead of down. thats not a good thing if you looking for clean fast and efficient. But these cars are not designed to be so. unless you want to rework the whole front end and do some crazy work to the rear of the car theres not much that will really help that much.

NOw if you are looking to decrease drag... fold in the mirrors and roll down the antenna it will at least make you feel hardcore
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Old 09-16-2003, 08:57 AM   #53
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Quote:
Originally posted by Hawk296
about decreasing drag.... differnt spoiler.. front spoiler.. those do not decrease drag. Those would increase drag. It might increase downforce making thecar handle better at speed but top speed woudl decrease and drag would increase.
No necessarily. Drag and lift are independent of one another. Well designed spoilers/lips at least, should aim to decrease lift without increasing drag. Not to mention drag comes from more than source. In theory at least a spoiler/lip combo could reduce drag, depending on the design of the car. I don't see how that would happen on our car, but fluid mechanics is my least favorite discipline.

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Old 09-16-2003, 09:25 AM   #54
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A lip spoiler combined with a reduced ride height is designed to decrease airflow under the car (a HUGE source of pressure drag) and route the bow wave more efficiently. A front wing (thing ALMS, open wheel cars) uses an inverted airfoil to literally help suck the car down to the track.

As for the wagon -vs- sedan aero debate... The rake on the wagon looks more slippery than that of the sedan's c-pillar. The trunk of the sedan and the bottom of the wagon's hatch are essentially the same so I'd call those areas tit-for-tat as to which is better. The waist spoiler should keep airflow attached to it enough to round the hatch, somewhat, and the top spoiler definitely causes a smoother separation than on the sedan... so, w/o testing, I say again that the wagon should have a lower cd using the sti aero parts.


To clean up an impreza the 2 areas of most concern are:

1. The sedan's c-pillar and the wagon's rear hatch
2. The belly pan
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Old 09-16-2003, 07:02 PM   #55
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I just thought I'd post what my barely modified RS does:

reaction time (I know it's not the car): .580
60 foot time: 1.89 sec
1/4 mile: 15.84
measured by track instruments

Forward G's: 1.12
measured by a G-tech computer

BTW: a G= 22mph of acceleration per second

is there anywhere to get these stats for other cars??
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Old 09-16-2003, 07:13 PM   #56
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Quote:
Originally posted by Machine Age Victim
I just thought I'd post what my barely modified RS does:

reaction time (I know it's not the car): .580
60 foot time: 1.89 sec
1/4 mile: 15.84
measured by track instruments
My barely modified RS (injen intake only):

R/T--------.610
60'--------1.979
330'------6.039
1/8-------9.465 at 71.37 mph
1000'----12.459
1/4--------15.005 at 88.51 mph

As for top speed, I have gone way past the 120 mark, probably close to 130, I could have gone faster as I was still slowly gaining speed, but was running out of real estate.
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Old 09-16-2003, 07:56 PM   #57
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I've never really tried to top out my car. I've hit 120, and it felt like there was a little more left in it, but I backed off. Years ago I had a heavily modified 5.0 mustang and I went up to 145 in that; it was pretty sketchy. At that speed, the air rushing over the car made it feel light and nervous.

How hard did/do you launch to do a 15.0005? In this thread everyone has made it clear that our cars get up and going from a dead stop faster than most, but I've also heard that it's better not to drop the clutch if you really want to keep the tranny together.
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Old 09-16-2003, 08:25 PM   #58
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Quote:
Originally posted by subarucyclist
How hard did/do you launch to do a 15.0005? In this thread everyone has made it clear that our cars get up and going from a dead stop faster than most, but I've also heard that it's better not to drop the clutch if you really want to keep the tranny together.
About 4k, slipped the clutch, didn't drop it. No clutch smell, slight chirp from the tires. The launch and the run felt perfect. I have only made maybe 10 passes with a sub 2 second 60', and i can tell you for a fact, that my 15.005 run felt perfect.
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Old 09-16-2003, 08:39 PM   #59
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Quote:
Originally posted by Machine Age Victim
I just thought I'd post what my barely modified RS does:

reaction time (I know it's not the car): .580
60 foot time: 1.89 sec
1/4 mile: 15.84
measured by track instruments

Forward G's: 1.12
measured by a G-tech computer

BTW: a G= 22mph of acceleration per second


is there anywhere to get these stats for other cars??


at what point does it record the G reading? your car is not accelerating at 1.12g the whole time...at that constant average acceleration, you would be going ~346mph (32.2 ft/s^2 * 15.84s = 507 ft/s = 346mph) by the end of the 1/4 mile.
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Old 09-17-2003, 12:03 AM   #60
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i have sentra 2.5 le, its an auto but still has the 2.5 engine. ive raced a spec v and they are quick. Some spec v drivers have beat rsx-s and with some mods, spec v's can hit 14's. (im also on a sentra board) and im not too sure but i think a spec v would beat a rs. stock vs. stock. The spec v has a 6-speed and with filled motor mounts, hop wouldnt be as big of a problem. how about weight difference? also, ive only gotten my sentra to 123 and i have 165 hp. probablymaking more to the wheels though since its only fwd.
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Old 09-17-2003, 01:01 AM   #61
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Dude, even if the speedo is off, it's not off by 10-15 mph, maybe like 5mph at the most. Just face it. A stock 2.5RS can run about 140 mph. And I'm sure a stock WRX will run about 150.


I have a Garmin GPS that I carry in my car. When my speedo says 75, I am actually going 71, according to the GPS, which is supposed to be accurate to +/- .1 mph. The error only gets larger the faster you go.
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Old 09-17-2003, 06:35 AM   #62
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Quote:
Originally posted by Foxy
Dude, even if the speedo is off, it's not off by 10-15 mph, maybe like 5mph at the most. Just face it. A stock 2.5RS can run about 140 mph. And I'm sure a stock WRX will run about 150.


I have a Garmin GPS that I carry in my car. When my speedo says 75, I am actually going 71, according to the GPS, which is supposed to be accurate to +/- .1 mph. The error only gets larger the faster you go.
Speedo accuracy is almost entirely dependent on tires. Unless you are running nearly new RE92s on factory recommended pressures, there is a slight error. For example, my S-03s are 205/50 and register approximately 3% smaller in circumference, which means they are 3 miles an hour off at 100 miles an hour. I would show 125 when I was going about 120 if I were inclined to do so (again ).
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Old 09-17-2003, 09:19 AM   #63
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Quote:
Originally posted by imprezin04
i have sentra 2.5 le, its an auto but still has the 2.5 engine. ive raced a spec v and they are quick. Some spec v drivers have beat rsx-s and with some mods, spec v's can hit 14's. (im also on a sentra board) and im not too sure but i think a spec v would beat a rs. stock vs. stock. The spec v has a 6-speed and with filled motor mounts, hop wouldnt be as big of a problem. how about weight difference? also, ive only gotten my sentra to 123 and i have 165 hp. probablymaking more to the wheels though since its only fwd.
wheel hop is horrendous in a spec V... I should know... that's our other car...
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Old 09-17-2003, 10:32 AM   #64
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Quote:
Originally posted by BAN SUVS
Speedo accuracy is almost entirely dependent on tires. Unless you are running nearly new RE92s on factory recommended pressures, there is a slight error. For example, my S-03s are 205/50 and register approximately 3% smaller in circumference, which means they are 3 miles an hour off at 100 miles an hour. I would show 125 when I was going about 120 if I were inclined to do so (again ).


And the age/accuracy of the vehicle speed sensor... and the accuracy of the speedo...

Even if a speedo was correct +/- 1% (which is beyond comprehension!) you would still be off. The accepted accuracy is +/- 10% at any given speed which greatly decreases the speedo's accuracy at high speed. So, again, playing the reality game:

assuming brand new tires at factory rec pressures your best bet is accurate to within 10% at any given speed (by law).

ANY deviation in tire size or pressure WILL decrease the accruacy of the speedo.... we don't usually increase the effective radius of our wheel/tire combo so we'll be increaseing the indicated speed on the speedo w/ every nm of tread depth loss. Unless you've had your speedo calibrated AT 120 MPH your BEST accuracy is within 10% (i.e. 10% too high a reading on the speedo).

Sorry the laws of physics don't ingore the impreza. Face it, your gauge goes to 120, anything over that is guessing. "Your buddy paced you" crap doesn't hold up either as his gauges fall into the same accepted % deviation.
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Old 09-17-2003, 12:10 PM   #65
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Quote:
Originally posted by dmitrik4




at what point does it record the G reading? your car is not accelerating at 1.12g the whole time...at that constant average acceleration, you would be going ~346mph (32.2 ft/s^2 * 15.84s = 507 ft/s = 346mph) by the end of the 1/4 mile.
no no no, maybe a fighter jet can have sustained forward G's, the reading was what it got up to, probably right off the launch (what throws you in your seat and almost snaps your head off) I once did a reverse then forward clutch drop,I did get whiplash from that, I wonder what that would read in G's
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Old 09-17-2003, 01:35 PM   #66
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jet fighters and john force's car...

i figured it was probably peak G...or your GTech was malfunctioning!
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Old 09-17-2003, 05:33 PM   #67
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Quote:
Originally posted by BOY
************Even if a speedo was correct +/- 1% (which is beyond comprehension!) you would still be off. The accepted accuracy is +/- 10% at any given speed which greatly decreases the speedo's accuracy at high speed. [/b]
Federal law requires that at no time the speedo read a lower speed than the vehicle is actually traveling. Your 10% estimate seems a little high to me, but it's possile, although only in the optimistic side. It won't read slower than your actual speed unless your tires are larger than stock, and who does that (besides Kostamojen? ).
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Old 09-17-2003, 06:56 PM   #68
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My speedometer goes to 140 cause its cool. Anway, I have two GPSs, one in dash, one handheld, both agree with each other. At about 75 MPH im showing a solid 80MPH on the speedo meaning Its reading about 5MPH high. At 120 actual Ground speed im reading around 127 on the speedo. My L speedo might be more crappy then your fancy RS speedos though...
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Old 09-17-2003, 11:27 PM   #69
BAN SUVS
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Quote:
Originally posted by Hawk296
My L speedo might be more crappy then your fancy RS speedos though...
Heh, not likely. The only reservation I have about GPS tracking devices is that they are not regulated- they have no real standards to measure up to as far as accuracy. And considering that standard issue US military GPS units were only accurate to one meter makes me question the absolute accuracy of civilian units.
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Old 09-18-2003, 02:12 AM   #70
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I work with GPS every day.
They are accurate to within about an inch.
Don't even question me.
The accuracy of car units, the speed would be spot on. As for location, probably 3 feet give or take.

Not me, but this is what I do.

Last edited by DJ 9iron; 09-18-2003 at 02:22 AM.
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Old 09-23-2003, 12:57 PM   #71
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I was having a bad day yesterday, it was late at night on a big empty road with a slight upgrade. *Theoretically* speaking the car topped out at a mind boggling indicated speed of ~103mph. She *theoretically* pulled all the way through 4th but fell flat on her face in 5th gear. Naturally on a flat road with more space the car would have gone faster, but I think it illustrates the point well that the RS is a weak top end car.

Since someone will ask...
Cobb Intake
MRT headers/cat
Greddy Cat-back
Mr. Josh Pulley
Exedy LW Flywheel
lowered on Prodrive P1 springs
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Old 09-23-2003, 01:10 PM   #72
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JC, thanks for doing the... um... research
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Old 09-23-2003, 02:27 PM   #73
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Quote:
Originally posted by DanzBorin

wheel hop is horrendous in a spec V... I should know... that's our other car...
Just buy yourself some stiffer motor mounts to fix the wheel hop, mostly you usually just need a stiffer front mount, but on some cars you need the front and rear
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Old 09-23-2003, 02:50 PM   #74
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Quote:
Originally posted by DJ 9iron
I work with GPS every day.
They are accurate to within about an inch.
Don't even question me.
The accuracy of car units, the speed would be spot on. As for location, probably 3 feet give or take.

Not me, but this is what I do.
Until recently I was also a civil engineer/surveyor by trade. GPS survey data is unacceptable in my region because it is not accurate enough for boundary or property line work, only for topo (it's close enough for that). That 3 feet of "give or take" on a moving vehicle, whose position is being measured many times per second, results in tolerance stacking that makes the readings unfit for use as absolute evidence. Sometimes it's right, sometimes it's not.
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Old 09-23-2003, 03:25 PM   #75
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Quote:
Originally posted by BOY
JC, thanks for doing the... um... research
The credit should really go to the young lady who put me in the proper mood for the testing conditions.

JC
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