your 1/4 mile times!!!!

[Jeffer]

Let "us" (s2 forum browsers) know what your quarter mile time is!!!!

I'll kick off, mine was 13,7 sec

http://groups.msn.com/solidcars/jefs...oto&PhotoID=82

And here's a link with all the meanest machines and there times!
http://www.syclone.freeserve.co.uk/rivals.htm
:wacked:

[*ZenithalRavage*]

Hmm.. after 34 views still no replies..... I think the rest is scared to put their times up here now they've seen yours

Anyway, I never tried a quarter mile but I reckon I should get something like 14,5s as my baby's motor is pretty much stock...

[Jeffer]

Yeah that's probably the reason :nana:

But there must be someone who has got a time.
And I'm very curious what other S2's do on the 1/4 mile!!

[Pisobiker]

OK, I take heart and give my numbers

My readings are all taken from a Gtech Pro Competition, which I've now tested a lot, and used to find out performances on several cars (mine and friends's) proving to be definitly accurate compared to figures given by magazines for same model of cars.

Readings where taken on a straight leveled road last February:

Engine setup:
Full RS2 upgrade, 3" turbo back custom s.s. exhaust system
Outside temp. ~6°C

1st 1/4 mile run:
12,862 sec @ 177,12 Km/h (110,63 mph)
0-100 km/h 4,751 sec.

2nd 1/4 mile run (same road, opposite direction):
12,851 sec @ 178,68 Km/h (111,60 mph)
0-100 km/h 4,595 sec.


Now I definitly need to take some other runs because in the meantime I've fitted a ~350hp chipset. Outside temps are way higher now (36°C !) so that I'm expecting performances to be sensibly affected by this.


Ciao

Marco

[Jeffer]

Wow, thats impressive.

[Pisobiker]

Well, it actually implies we assume the Gtech gives the real values.
As I said, looking at the power and torque readings of several cars, it seems precise. But to be 100% sure I should find the way to make a run with both Gtech and an optical device simultaniously.... ....no way to do that around here!
Will find another way to check if device tells the truth.

Anyway I tryed a run this morning. Had a car coming behind me so I had to start in a hurry :mad:
My start was really bad, not revving up enaugh and letting rpm drop too much while releasing clutch. Didn't go over a 14,1 sec in the 1/4 mile

Will try again later, or maybe tomorrow.

Outside temperatures, anyway, make some big difference. Compared to this winter, boost kicks in some 500 rpm later and also engine doesn't show same grunt (at the moment we have something wery close to 40°C :eek2: ) and Gtech also detects less power and torque ~275hp at wheels vs ~310 (both with 350 hp chipset) of last winter
All this makes sense, being the 5°C to 40°C a 12,6% drop in outside air density !


Ciao

Marco

[Jeffer]

Hi Marco,

Where did you buy the g-tech computer? And how much did you pay for it? That's a good option for trying quarter mile times and all other sorts of tests.

The heat really keeps the engine power down. My quarter mile time was driven at 32 degrees.

So i probably could do better when cold, but i just have to wait for another sprint competition , or buy a g-tech computer

Jeffer

[Pisobiker]

Jeffer, take a look at this site:

http://gtechpro.com

I bought it last Christmas (self-gift, he he )
If I remember correctly cost was around 260-270 U.S.$ + shipping (the total was ~320 Euros) bought from a U.S. dealer.

The device is really cool! As I already said, assuming it's accurate, it has a lot of functions (you'll find out reading from the site) and now, with the new free software, runs both with US and metric units and, downloading data to PC, you can store and print all your figures.
Following I'll put an example of some runs of mine I did for detecting max hp and torque.

I gave the device immediatly credit because I realyzed it is very simple in its functioning:
all it needs to get all the data (accelerations, Hp, torque and so on), is vehicle weight (you input it, and precision here is very important), engine rpms (detected from alternator noise frequency variations from cygarette lighter), and acceleration variations.

Speed=acceleration x time
Power=mass (total including driver) x accleration x speed
Torque= power / rpm / conversion constant

Ciao

Marco

P.S. On this example device detected some sort of "noise", maybe when changing gear, so the Max HP written in the right side box isn't real, it is top of noise. Real can be seen on the graph: ~200 kw and 425 Nm of torque (3th gear, at wheels, including aerodynamical drag).

[Jeffer]

Cool device, NEED ONE NOW!!!

[Pisobiker]

OK,
did some other runs yesterday (see attached jpg)

Comparison test of the one already mentioned (green one, 1/4 mile in ~13,9 and not 14,1 as I said previously), second one (red) and last one (main one in black).
From this "speed vs time" figure are visible all the mistakes in the runs (I added arrows to show them):

Green run: I kept initial rpm too low and let rpm drop too much when releasing clutch (green arrow) -> 1/4 mile result 13,941 sec

Red run: Initial rpm slightly too low but expecially shifting to 2nd gear at too low rpm ( red arrow) with consequential too big drop in rpm -> 1/4 mile result 13,363 sec

Main run (black): Initial rpm ok, on clutch release I let rpm drop a little under max torque region (better visible in the "rpm vs time" graph). Then I did a stupid mistake (black arrow), I released throttle slightly too early when 1/4 mile wasn't reached yet (just a couple 10ths of second, though), still better visible in the "rpm vs time" graph). -> 1/4 mile result 12,876 sec ... probably can do better ....


Ciao

Marco

P.S. Main run was taken with outside temp. at around 30°C

[Jeffer]

Hi marco,

Do you have the pro or the pro competition?

BTW: check this link http://www.suprastore.com/top2514miles.html

greets

[Pisobiker]

I have the "Competition" one. Here is the link on the site you've suggested


http://store.yahoo.com/supra/gtecpermet.html


This is where I bought it


http://www.racerpartswholesale.com/gtech.htm


The other Gtech, the Gtech Pro (non "Competition") has limited functions and doesn't allow downloading to PC and managing data.


Marco

[Doug_RS2]

I have VAG-COM and will do a couple of runs soon, but what are the sums that calculates BHP and torque - that would be quite a cool graph to show from a single gear run - I assume it takes into account weight, time, acceleration, resistance - doing these in different gears at different speeds might show if the formula is accurate.

I was dissapointed with a 14.0 second run - I did have 2 passengers in the car, run slightly bigger wheels and only tried it a couple of times - that time also included reaction time of about .5 second if I remember right. The power at the time was 322 and 350lb/ft.

[Pisobiker]

Originally posted by Doug_RS2
I have VAG-COM and will do a couple of runs soon, but what are the sums that calculates BHP and torque - that would be quite a cool graph to show from a single gear run - I assume it takes into account weight, time, acceleration, resistance - doing these in different gears at different speeds might show if the formula is accurate.
....

Doug, I'm not sure I fully understood your statements, but if you want to get power and torque readings Vag-Com needs to record following data (in my case I of course use metric units):

speed (meters per second) vs Time;
acceleration (meters per square of seconds) vs Time;
rpm vs Time;

the smallest the time period the more accurate the readings.
Then, for every time period (which means for every rpm period) you must calculate Power and Torque and then build the graphs.

This is exactly what does GTech and other acceleromiter based devices automatically (once setted rpm and wechle weight).

Anyway the formulas are the following:

Being:

a =Acceleration
t =Time
F =Force
V =Speed
Vo =Speed at the moment you start the run
M =Mass (vehicle+people inside+fuel+whatever weight) in Kg

then Power at wheels (in Watts) at given time (rpm) is:

W= F x V;
but since F = M x a;
and V = Vo + (a x t)

then W= M x a x (Vo + (a x t));

starting from standing still Vo=0 (zero)
so W=M x a x a x t (where t is the fraction of time your readings are taken)
which means
Kw= (M x a x a x t) / 1000

At this point Torque (Nm):

Nm = Kw x 1000 / rpm


So all the numbers assume that time, acceleration, speed and rpm readings are correct, + your imput of wehicle weight is correct (note anyway that rpm only needs to compute torque, not affecting power calculations).


Marco

[Doug_RS2]

Cheers

How does wind resistance affect this Marco? If you do it from 0mph in 1st - it's going to give different results from doing it in 5th from 80mph up?