hacker-pschorr

February 2009 Road & Track they tested three consumer performance meters against their Racelogic VBOX – which they use for all of their official tests. Since these have been criticized quite a bit on this forum (and most others) I found this test very interesting.

The three challengers:
Dodge Charger SRT8 comes with its own device.
G-Tech Pro SS
Dynolicious software available for the iPhone / iPod Touch

Here are the results:




928 Content – here is the G-Tech results from Tim Murphy’s Supercharged 1988 5-speed from this post:


https://rennlist.com/forums/4110918-post9.html



If you apply the same percentage difference between their G-Tech and Tim's, that puts his car at a 0-60 of 3.65 seconds and a 1/4 time of 11.30 @ 135.4mph

This is assuming my 4th grade math skills are still in tact.....

dr bob

Interesting that the closest competitor is the Dynolicious software for the iPhone. Cheapest solution by far if you happen to have an iPhone or iPod Touch already. Unfortunately, it doesn't yet offer the graphing/printing/download capabilities of the GTech Pro. Yet.

Tony

Ive ran my GTECH in unison with the timing at the drag strip here in Vegas. IIRC always with in .1 sec and 1mph of the trap.

Now whats that roll out value

IcemanG17

Dynolicous is the cost effective way to go...hard to argue with $12.99......I've used it quite a bit....its not perfect, but works more than well enough!

Larry928GTS

Here's another test with the G-Tech compared to the Vbox:
http://www.performancebox.co.uk/down...CHvPB_Test.pdf

Kind of interesting that it also shows the G-Tech giving a little slower results with the rollout set to zero. With it set to what seems to pretty much be the standard 12" rollout, the G-Tech's times are a good bit closer.

nsantolick

http://www.youtube.com/watch?v=0-DFbJQbeSY



iPhones Rule...








Nick - S4 - PA

RicerSchnitzzle

I've had my G-tech for a couple years now and it works very well.

Problem with all of these is when you start talking horsepower results... You're weight must be perfect, flat ground for the run and it doesn't account for friction of tires or wind. You also have to have it mounted securely..jiggles can through things off. I've found it's about 29-35hp short @ 70mph depeneidng on S or S4 drag coefficient. And if you have any wheel spin or hop, the change in rpm throws every thing off. However 0-60 and 1/4 times are pretty much spot on.

Still it's more usefull as a comparision tool than a straight dyno. If if the results are not spot on, they are consistant for the same car on the same road, so you can use it to tune just the same. Set a base line in the morning, tinker all afternoon and check for results in the evening. It really helped me dial in nitrous jet levels, along with my LM-1 A/F. Great $200 investment.

I also have Dynolicous on my I-touch. Pretty cool, and for $12 is a must have toy. My G-tech is permanently mounted in the car so I've stuck with it.

dprantl

Another thing that makes these devices inaccurate is the amount of suspension dip that occurs during acceleration. Some devices allow you to enter this value while others take some average. That was a pretty stupid test since they should really have done it on a drag strip with a real-world 1/4 mile time to compare them all to.

Dan
'91 928GT S/C 475hp/460lb.ft

heinrich

I think we've always suspected this My G-Tech runs were 5.6 sec. So who knows how much it really was.

hacker-pschorr

The VBOX is how they test every car for every issue. If you check the Road Test summary in the back of the mag, those numbers come from the VBOX used in this test:

http://www.roadandtrack.com/assets/d..._rtSummary.pdf

In the past they used a 5th wheel device. The GPS based systems like the VBOX were shown to be more accurate so most if not all publications (and manufacturers) switched to GPS based devices.

FWIW here is Tim's 88 versus a stock 91 Auto using the same device, settings, road etc.... Graph adjusted to show the rollout setting.

SharkSkin

The iphone solution is only cheap if you already have or are planning to get an iphone. When you factor in the cost of the phone, it's about the same price as a G-tech.

IMHO these devices are only good for comparing between runs, e.g. tuning and seeing if you helped or hurt. The absolute numbers are always open to question IMHO. Having said that, IMHO the most important thing is consistency. I am assuming that all 4 devices were active in the same car at the same time during the runs, and it's interesting to note that on the 1/4 mile runs, half of the devices thought the 2nd run was faster than the first, half thought it was slower.

nsantolick

I'm adding the dyno app for my iPhone. Does anyone know what a fully fueled automatic 1989 S4 weighs? The only mod is a Roger X-pipe and high flow cats...





Nick - Hazleton, Pa

RyanPerrella

im sold

Just bought it, looks like a great tool to do before and after mods on the car too.

I'll try it out tomorrow

Tony

somemore "ICandy"

http://www.innovatemotorsports.com/products/ot2.php

Vilhuer

There are several phone softwares for different phones and they all seem to work well enough to be helpful in trying out how changes into car work.

http://www.racechrono.com
http://www.tempes.com