G-tech Question

XXBULLETSXX · Jul 27, 2005

Has anyone used a G-Tech to measure horsepower?
My friend and I went out in his 03' Cobra tonight to G-tech his horsepower. Now he has a few things done to his Cobra like pullies and exhuast. There maybe others but I can't remember them.
Ok here's the question, when we ran it the highest HP measured was 325. Does that seem right? Sounded a little low to us. Has anyone else had this experience?

XXBULLETSXX · Jul 27, 2005

I forgot to tell you all, we video'd it. I'll try to post it up when we get it uploaaded on the computer and edited down to a reasonable length.

I'll keep you all updated.

Sellout · Jul 27, 2005

thats seems about right, that is rwhp. Did you just do a pull in one gear? Or just ran the 1/4 mile? They recommend for accurate HP reading, just go hard one gear and shift easy so not to throw it off at all.

XXBULLETSXX · Jul 27, 2005

We nailed it all the way thru 3rd, shifted into 4th and then slowed down. The instuctions that came with it said to start from a stop, shift thru the gears redlining each gear until 120MPH. It said there was two ways to stop the reading, either reaching 120MPH or slowing down.
The highest readings came from third gear. I think that was because the car wanted to spin the tires in 1st and 2nd.

So did we do it wrong? I just wouldn't see that large of a loss of HP to the rear wheels with a manual transmission. A stock an 03 cobra should have like 390HP, so losing 65HP seems a bit much. Not to mention he has pullies which increases the boost put out by the supercharger.

I am by no means an expert, I'm just trying to figure out if the G-Tech is accurate and that was a bad run or if the G-Tech can't be trusted for that reading. Hey maybe the G-Tech was very accurate and that's what the Cobra puts to the ground.

productj1 · Jul 27, 2005

On horse power tv they had a stock cobra make 364rwhp. So it seems a little low to me.

BennyBlown2v · Jul 28, 2005

I have one of the G-tech "pro" models, like the 30 dollar ones on ebay. The horsepower is just weight vs elapsed time, but it's pretty effective to get an average peak, or atleast an idea of the range your dealing with. My car it registers around 250, my dads volvo gets around 220. Fun toy, but it is a toy heh.

XXBULLETSXX · Jul 28, 2005

I'm thinking it was just a bad run. If we had pulled a 360 we might have thought it was just a little lower than what it should be.
As I'm writing this it makes me wonder about the weight entry we put in. If that was wrong than the horse power reading would be wrong as well.
Here's what we did, tell me if we did it wrong:
We used the weight on the door of 4450lbs, then we subtracted two passengers (rear seats) of 180lbs each which gave us a total weight of 4090lbs.
Is that right, my friend said that the weight of the car included 4 passengers at 180lbs each. Now he ways about 190 and I'm 230 should we have added the additional weight above 180 for each of us? I'm thinking so, Heck I'm thinking that the weight on the door doesn't include 4 passengers, but what do I know.

What do you guys think?

Pittsas · Jul 28, 2005

Curb weight
Coupe 3,665 lb. (1,662 kg)
Convertible 3,780 lb. (1,715 kg)

This is empty so you still need to add wieght for passengers

XXBULLETSXX · Jul 28, 2005

Is that the weight for a 03 Cobra?

KronicRacer · Jul 28, 2005

ive had the opposite problem.

launching with traction controll on made the gtech spit out 425 hp . i was like wow thats awsome power and all. one problem though ........... mines just a GT. actually when i did get it close to working right it was spitting out 250 hp. which after seeing other peoples dyno readouts is generous number for a bone stock car (at the time). try the test with ust one person in the car vs having 2

with pullies and exhaust that cobra should be close to 400 some odd hp

BooWFO · Jul 28, 2005

You need the weigth to be right. Which means you need to have the car on a scale with the same amount of fuel in the tank and people in the car. In order for it to be right. Or since breaking the speedlimit doesn't bother you just do a 1/4 mile run and use any of the many conversions to see what the HP is of course you still need the correct weight of the car. Also the Gtech number will be lower since drag plays a role in the numbers it gives you. All and all I like the gtech but don't take the data from it as been written in stone.

CanadaStang · Jul 28, 2005

Also keep in mind the G-tech cannot tell if it's windy or not. Trying it into a head wind will give you lower hp #'s, with a tail wind you'll get higher hp number's. The hp calculater on the g-tech isn't designed to give you the same #'s as a dyno,as it cannot compensate for wind resistance, some cars are have lower wind drag than others etc. Just use it on your car as a guide line, then if you ever do any mods, then you can run it again to see if there is any improvement.

BooWFO · Jul 28, 2005

Ughh was looking for the I agree smiley. oh well that's what I use mine for. Also been using it to hone up my launch. The whole 0-60 thing you know. Keeps me semi-legal.

XXBULLETSXX · Jul 28, 2005

BooWFO said:
Ughh was looking for the I agree smiley. oh well that's what I use mine for. Also been using it to hone up my launch. The whole 0-60 thing you know. Keeps me semi-legal.

keeps you legal....
Ya, I bet the cops like it when you accelerate that quickly and it makes them smile when you chirp the tires.

I'm just foolin' with you, I know you were giving me some razzberries about my HP runs in the country of which I'm sure I deserve.

BooWFO · Jul 28, 2005

Hey I said Semi- legal besides I can use the "well I don't know it just started accelrating I guess I need to take it in for that recall but I haven't got notified yet."
BTW how fast were you all trucking??? cause I'm pretty sure you all would've broke 120 in the cobra.

Pittsas · Jul 28, 2005

XXBULLETSXX said:
Is that the weight for a 03 Cobra?

yup

XXBULLETSXX · Jul 28, 2005

Ok, does that weight include any passengers?

And, does the weight on the door include passengers? The sory that I heard is the weight on a passenger car includes 4 passengers at 180lbs each. Is this accurate?

Thanks guys for all your help!

foncarelli · Jul 28, 2005

I have an Pro SS on auction at Ebay right now.

CanadaStang · Jul 28, 2005

XXBULLETSXX said:
Ok, does that weight include any passengers?

And, does the weight on the door include passengers? The sory that I heard is the weight on a passenger car includes 4 passengers at 180lbs each. Is this accurate?

Thanks guys for all your help!

The weight on the door is the maximum gross vehicle weight. In other words, it's what the car would weight if it was loaded to it's maximum carrying compacity

DBMSTNG · Jul 28, 2005

you need to run on a flat surface and have the weight perfect. if you spin the tires, it will cause the power readings to be low.

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