I expect that there are just as many variables using dynos. The NET HP provided by the GTech probably makes the most sense, since it is a real world measurement that takes everything into consideration. I think it is good for comparing cars to one another as long as there is some consistency in road surfaces (rougher would cause more drag, etc.), temperature, levelness, etc. The effects of wind etc can be mitigated fairly well by averaging numerous runs in each direction, and not just picking the highest one which may have been the result of having a tail wind in one direction. It isn't perfect, but makes for interesting comparisons.

 

They also have a cool program for the iPhone called 'Dynolicious". It works very much like the Gtech and is only $12.00
They have tested it in a few mags and found it to be as accurate as the Gtech. It prints out cool graphs as well. I will try to post one from my car. The trick is to have a PERFECTLY level surface to run on and to also mount the unit in the exact center point of the vehicle.(lessens the effect of pitch and yaw)

Boys, we are in luck, because your center console arm-rest is in the exactish center of the car. You can strap your iPhone there with a velcro strap and it gives some really accurate numbers.
I'll see if I can post a graph in a few minutes, but I gotta get back to work!

 

I had heard about this app, but hadn't found it yet. I may have to buy it and compare results with the GTech. Thanks.

 

What if the car was tested with the g tech in a tunnel(no wind disturbance) ? would that provide more consistency?

 

Hey Cattman etc., I went out with "justatoy" last weekend and we did several runs with his g-tech.

Car 3,320lbs + Driver 175lbs = 3395 lbs +/-

3 decent runs with the g-tech gave the following 3 RWHP numbers: 300, 286, 301. I think its fair to say 296 RWHP.

As a point of verification, there was an article in Excellence a while back that stated 297 RWHP as measured on a Mustang Dyno.

On measuring, car was completely stock with OEM 2005 Carrera S Wheels with Stock Exhaust, Seats, Panels, Brakes (Red), and aboult half a tank of fuel.

Hope this helps.

Jason.

 

It would be more consistent, but there would still be aerodynamic drag. Plus, where you are, there would likely be a bigger impact of that low density hot air you have in Dubai.

 

Check out Rev too:

http://www.devtoaster.com/products/rev/

 

FYI - I took the average of the 3 good runs becuase there were different wind conditions (which the g-tech is sensitive to based on the ability to accelerate in the real world).

Cheers,

Jason.

 

Hi Jason. It was great meeting you for our afternoon of fun with Stacy. By the way, you might want to check your math regarding weight of your car and driver. Did you see the video we posted of the runs after you left?
Ken

 

I see...

over here we only have 3 months of "winter" (lowest ive ever seen is around 16 C) and the rest is just summer

hmm, i dunno. but i believe that this g tech can be consistent enough(hey nothings perfect ) to at least prove and show a gain/ loss of hp or torque with any mod. It might not be perfect for rwhp but i think it is effective in registering improved power. My main fear is that some mods could possibly be affecting power instead of improving it.So the g tech would at least rule that possibilty out.

 

You are right! I was referring to crank HP since we have been talking about that pretty much the whole thread...

 

Excellent program and not to far from reality. I saw a comparison of Dynolicious, vs Vbox vs actual timing traps in the 1/4 mile and Dynolicious was the most conservative. So whatever number you get, you probably went faster. So it is more like a dynodynamics which breaks your heart. I plan on trying it next summer at the dragstrip to see how it compares to the Vbox and the timing track system

 

You're exactly right. The GTech is great for measuring impacts of any mods, since hopefully everything else is fairly constant. This is what Stacy has been doing with his. The absolute numbers may be a little off, but the relative numbers should be very helpful.

 

Funny you say this....but back in the early years I used my Gtech on my cars.I use to talk about it quite often at the engine shop...WELL...one guy called BS!
So test and tune was the next friday and he took it to the track.
3 times he ran it down the 1/4 mile and 3 times the results came back WITH a timeslip.
The next day he brought it back to me with the time slips and apologized........the Gtech was within' a 1/10 of a second for time and +/-1 mile per hour for speed....REALLY amazing!

Stacy

 

Alright that's it, next car related purchase is a g tech