Welcome to the North American Subaru Impreza Owners Club Friday July 11, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Archives > NASIOC Archives > Technical Forum Archive

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
 
 
Thread Tools Display Modes
Old 05-03-2000, 06:05 PM   #1
edekker
Scooby Newbie
 
Member#: 143
Join Date: Aug 1999
Location: Kanata, ON, Canada
Vehicle:
1999 Impreza 2.5RS
Supercharged - and STOLEN

Post

I think it's a great device too. Ther are a number of us who use it.
But like boxerman pointed out, it has to be used carefully.

I've got some pointers on its use, which someone might see as useful.
I invite anyone to please add to this (or even correct me please) - to help me or anyone get the most out of it.

I find that the power cord puts a strain on the unit, moving it, causing it to loose calibration in short order. What I found helpful is to wedge the cord between the utility tray and its cover while ensuring the cord is not taught, at least not between the unit and the tray. This also reduces the cord's effective mass - the forces enacted upon it (under hard acceration) do not cause as much stress on the unit - its effect on the unit's calibration is reduced.

I suggest not to put too much credence on its 1/4 mile trap speed calculation - it is generous to say the least.

When performing g-force runs (skid and instantaneous) make sure it's done on a flat, very level area. If the area is not level, your zero cal will be off. There's away to check that. Once the meter is zeroed, drive slowly around the circle by 180 degrees and stop. The reading should be still be zero. If it's off by a significant amount, say by 0.03g or so, your measurements cannot be trusted - to that level of accuracy anyway. The area has got to be clean - no dust, sand or dirt of any kind. As you make the turns, try not to make the tires screech - at that point already, the tires may very well have lost alot of its grip.


When entering the vehicle's weight, make sure you enter the total weight. That includes the curb wt (all fluids topped up, including the gas), yourself, mods, stereo stuff, everything. And remember, it measures all consumed HP at the wheels including power to overcome wind drag, which becomes substantial approaching terminal velocity.

When you are making concerted runs - to compare a mod for example. Great care has to be taken in your choice of test methodology, to ensure an accurate, dependable result. We may be talking differences of a few horsepower here. Fortunately, while the g-tech may not be accurate in the absolute sense, it could be depended upon as accurate in the relative sense, as long as the test methodology is sound and reproducible.

The key is, to remove sources of error and uncertainty as much as possible. Reducing uncertainty is crucial - the nature of the car's performance (with which the mod affects) needs to be determined and its test methodology tailored to that end.

Possible sources of uncertainty are -

Clutch engagement, throttle control.
Gear shifting, shift points.
Surface gradients, textures, location.
Wind direction and speed.
Barometric pressure, humidity and ambient temperature.
The list goes on...

Instead of accelerating from a dead stop, you can make a rolling start (clutch already let out), say from a steady state 1000 RPM or just rolling on idle (set the g-tech for 'ready' during this steady state) and mash it. A lot of measurements can be made without ever shifting gears - just leave it in first and mash the throttle to redline. These two methods alone can reduce errors alot. If you make several such runs and take the average, the erreors are reduced even more. If you are consistent, taking care of wind, temperature and other effects, I wouldn't be surprised if changes in a couple of HP can be measured with certainty.

Remember, you needn't be concerned with the actual HP, just the changes in HP the mod makes.

Have fun.
Ed.

[This message has been edited by edekker (edited May 03, 2000).]
* Registered users of the site do not see these ads.
edekker is offline  
Old 05-03-2000, 07:31 PM   #2
Joel Gat, 1.8L
Scooby Specialist
 
Member#: 32
Join Date: Jun 1999
Post

Hello,

Ed, the biggest comment I have on what you wrote is that you absolutely cannot do skidpad work without squeeling the tires. It's just a fact of life that tires make noise near their limits. Anyone who autocrosses can tell you that you have tons, and I mean tons, of traction left at the onset of squeel.

Last weekend, I let my rental Neon squeel all track session long. By the end of each 20 minute session, my tires would smoke and continued to smoke for about 10-15. Was I beyond the traction limit? No! Otherwise I wouldn't have been passing RX7s, NSXs, and hundreds of 'rustangs and cam-birds.

And the other comment I have is about the utility of the G-Tech. It's a very nice tool so long as you realize that you'll never get perfectly repeatable results. 10 degrees colder on the second day means denser air, colder asphalt, colder tires, etc etc etc. All those variables add up. Plus if you angle the GTech ever so slightly, the data sucks.

But all nay-saying aside, plus or minus a couple horsepower, it's pretty accurate against itself. It will show improvements and stuff like that. The reason the 1/4 mile top speed is too high is that GTech measures the top speed you attain rather than the average of the last 50 feet or whatever distance they use at most drag strips.

JYD
Joel Gat, 1.8L is offline  
Old 05-03-2000, 08:52 PM   #3
edekker
Scooby Newbie
 
Member#: 143
Join Date: Aug 1999
Location: Kanata, ON, Canada
Vehicle:
1999 Impreza 2.5RS
Supercharged - and STOLEN

Post

Hi Joel,

You could be right about the squeal. My experience is with the stock tires only. I had found that when I backed off on their squeal the grip shot up. I guess it depends on the tires and the shape they're in, as well as the kind of surface you choose for the test. I suppose what I'm saying is that one should be attentive to tires' grip at or about their limit of adhesion. Fortunately, when the g-tech is set to skid-pad mode, it calculates a running average during a 5-second (or so) aperture, (as opposed to instantaneous which measures the peak g-forces). That would help the person seek out that elusive max adhesion as the skid circle is negotiated.

Thanks for the input Joel.
Ed.
edekker is offline  
Old 05-03-2000, 10:27 PM   #4
EddyRS
Scooby Specialist
 
Member#: 1257
Join Date: Apr 2000
Location: In the Valley.....Somewhere...
Vehicle:
2000 GC8 WRX
93 RS-W Wagon (White) RIP

Talking

Thanks Guys,

I am glad I asked......from what the shops that I talked to...they said it was not very accurate...and that included Bozz

As long as I am careful I should be able to get good reading from the G-Tech...that is what I want.

I have the perfect place to test. It is a out of the way road...about 5 miles long...all straight, and almost no traffic at all. The great thing about this is that it is almost perfectly flat (maybe only 2 feet deviance for the entire length) Plus the road is almost exactly at sea level.

So I am planning on doing extensive testing of the performance of my new suby, starting with bone stock....and then going from there.

Thanks for all the information, and advice....when I get the G-Tech...I will make sure to follow the instructions carefully.

I will pass on any who wants it, the findings I make.

Cheers

Eddy L.
MY00 BRP RS Coupe
EddyRS is offline  
Old 05-04-2000, 12:01 AM   #5
EddyRS
Scooby Specialist
 
Member#: 1257
Join Date: Apr 2000
Location: In the Valley.....Somewhere...
Vehicle:
2000 GC8 WRX
93 RS-W Wagon (White) RIP

Question G-Tech Meter???

I am looking for a Good way to test performace on my 2000RS. But I do not want to do anything that will void my factory warranty.

How is the G-tech performace meter.....I have talked to two shops and they basically tell the unit is a Piece of S@#$. I want to have something to fairly accurately compare any gains from the mods I plan on purchasing soon for my suby. Is there anything else out there....like the G-Tech...or is the G-Tech an allright unit to measure performance gains.

Thanks for any help you guys(and gals) can provide for me.

Eddy L.
EddyRS is offline  
Old 05-04-2000, 12:42 AM   #6
boxerman
Scooby Newbie
 
Member#: 644
Join Date: Dec 1999
Location: Hoboken, NJ, USA
Post

Everything I have heard about the G-tech is that it is a great unit and correlates well with dynojet #s. Of course the GIGO rule applies (garbage in/garbabage out) You need to set it up correctly and input the correct vehicle weight. Also the tecnique used to generate HP figures is important.

Follow the instructions and it is very accurate and with an AWD car you don't have many choices anyway.

Tim
boxerman is offline  
Old 05-04-2000, 05:05 AM   #7
RallyGuy2k
Scooby Specialist
 
Member#: 1146
Join Date: Mar 2000
Chapter/Region: International
Location: Houston/LA/NYC
Post

I've got a G-tech and I love it. Keep in mind it's also great to test out different driving techniques. The acceleration numbers are very accurate. However I wouldn't bank on the horsepower numbers.
Go for it!
Tre'
RallyGuy2k is offline  
Old 05-04-2000, 01:15 PM   #8
BoomerRS
Scooby Specialist
 
Member#: 1271
Join Date: Apr 2000
Location: W Hartford, CT USA
Vehicle:
98 RS
****in Rally Blue

Question

I have been following this thread because I was thinking about buying one (lots of great info, thanks everyone )... any hints on the best place to get one and what I am going to spend?

Boomer
98RS
BoomerRS is offline  
Old 05-04-2000, 01:50 PM   #9
thepas
Scooby Newbie
 
Member#: 817
Join Date: Jan 2000
Location: El Segundo, CA, USA
Post

My roomate has one for his and his dads Mustang, I used it, and we use it all the time! It's a REALLY GOOD TOOL, yet you have to remember, it is not PERFECT, but the numbers are really close. I love the dang thing, yet if you have a chance to do some pulls on a Dyno, or run at a REAL drag strip OF COURSE YOUR GOING TO PICK THEM!!! but how many people can be done putting on a Turbo kit at 3am in the morning and go bust some 1/4mile times right then and there????? ahahahaha I love it!

Kyle
thepas is offline  
Old 05-04-2000, 02:12 PM   #10
wac
Scooby Specialist
 
Member#: 689
Join Date: Dec 1999
Chapter/Region: NESIC
Location: Lebanon, NH, USA
Vehicle:
2005 Outback 2.5 XT
Champagne Gold Opal

Post

As others have mentioned, it works well as a repeatability instrument. I only have faith in the G-force measurements, as the others have too many variables involved.

My only real gripe with it is with the 0-60 and 1/4 mile time function; it holds the 0-60 display for a second or so, and then that number is gone (replaced by the attempt at a 1/4 mile time) if I'm not paying attention. It's supposed to be smart enough to determine if you're still going for the 1/4-mile, but mine isn't that discriminating, and often continues to report my 18+sec 1/4 mile times even though I've already evened out at 70mph.

It's a neat toy for $115, and the best deal you're going to get for it is probably 5% off, if at all.

-WaC
Wayne
wac is offline  
Old 05-05-2000, 09:07 PM   #11
bryanw
Scooby Specialist
 
Member#: 807
Join Date: Jan 2000
Location: Greenville, SC
Vehicle:
2002 WRX Wagon
Black

Post

I've got a GTech Pro and I hate it!! The numbers are never even close to accurate. 0-60 times are horrible. It always shows 7.2-7.5 s now, but it always stops counting at 50-55 mph. It's just stupid. 1/4 shows 15.3 and 86 mph when I'm about 200 yards away from the 1/4 mile marker and currently doing about 75 mph when it cuts off. All the numbers are exagerrated. I don't see how it could void any warranty or anything. The thing just sticks to your windshield and has a built-in accelerometer. It uses that (just like G-force) to make all the measurements. It's completely independent of the car's mechanics.

$100 and you can have mine. Includes shipping. Email me. That goes on the list of things I've wasted my money on (with the moonroof air deflector and Stromung exhaust).
bryanw is offline  
Old 05-05-2000, 11:49 PM   #12
edekker
Scooby Newbie
 
Member#: 143
Join Date: Aug 1999
Location: Kanata, ON, Canada
Vehicle:
1999 Impreza 2.5RS
Supercharged - and STOLEN

Post

bryanw,
You're g-tech is probably bum. I'd return it under warranty. My g-tech churns out good numbers. There's no reason why yours can't.
Ed.
edekker is offline  
 

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS : Avon Tech-R 225/45/17 tires - Los Angeles fredtga SCIC Private Classifieds 2 07-07-2010 02:16 AM
WTB Locally: G Tech Pro Competition or G Tech Pro RR meter manchild83 New England Impreza Club Forum -- NESIC 8 04-15-2005 03:41 PM
FS: Valentine One Radar Detector and G-Tech Meter! vtfan Private 'For Sale' Classifieds 6 08-28-2004 02:56 PM
G-Tech meter FS mitch808 North West Impreza Club Forum -- NWIC 0 04-25-2002 07:59 PM
('93-'01) g tech meter accuracy? GQ Impreza Forum 6 10-12-2001 08:41 PM


All times are GMT -4. The time now is 09:10 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.