G-Tech numbers

[John Berger]

After 5 runs last night, my best numbers were 250, 246 and 243 which average out to 246. 3 HP at the rear wheels. For the heck of it, I threw in a single run last week that produced 266, threw out the 243 and that averages out to 254 HP. I had some lows of 178 and 189 and 227. Not sure what happened there. I also made some measurements only going through redline in fourth gear. I'm not really sure that makes a difference. All runs that I have made so far have been with an estimated weight of 7000 lbs and near dusk. All other factors have been consistent. These numbers put torque output in the area of 527-543 ft. lbs.



Questions



1) Is it necesarry to run through redline in every gear? Once you get to redline in fifth and back off, should the stop be sudden (safely speaking here) or gradual. I'm not sure running through redline is the best way to utilize this device on our trucks, since most of our power is made in the lower RPM band and after 2700 the dropoff begins. I am interested in any opinions. TIA



John

 

[StakeMan]

First off, I think you are guessing a little heavy on the weight. I have an 01 2500 4x4 and it only ways 6840 with me in it and a 1/2 tank of fuel. I think you would want to keep the shift points within the power band. shift just before it starts to defuel.

 

[DavidTD]

John,



I would run through the gears as if I were racing it. Meaning, I would have shifted before redline. I probably shift between 2700 and 3000 depending on which gear I am going to.



As far as weight, we have the same truck I think except for mine being 4x4. Mine weighs 7740 lbs with a 3/4 tank of fuel. You are probably about 7300 but I would weigh it to be sure.



Did you compute 1/4 times? I think for manual Diesels, 1/4 mile mph is a better gauge of power over ET. The gear changes kill us for ET unless your name is Eric McBride.



My truck runs a mid 17 @ 80mph which calculates to 306 rwhp with about the same mods. I'd love to hear what you end up coming in at.



Keep me posted, please.

 

[John Berger]

I weighed the truck with a full tank of fuel two weeks ago with me in it. Total weight - 7060 lbs. The tank was at 3/4 so I subtracted 60 lbs to cover the fuel difference. I will try it again and shift at the points you mentioned David. I think the numbers should be a bit higher. And no, I have not done any quarter times as of yet. Will post them when I do. Thanks for the replies.

 

[FDziurda]

John,

I have had one of the G-Tech's for over a year. If you're only trying to approximate your truck's performance, then guessing the weight of your truck is fine. It really only takes a few minutes to load it with fuel and go find a scales, which might provide you with better readings. Besides, it's kinda nice to know what you have, prior to hauling a trailer/ 5th wheel, etc.



I have a steel camper shell (~600#), on my 2500 4x4, and my truck weighed in at 4,300# front axle and 3,300# rear axle (7,600# Total), loaded with fuel but without me in it.



Last time I checked it with the G-Tech, I was seeing ~182 HP average (Stock ETC Truck).



Pick a section of flat road and make several runs, both directions; until you begin to see reasonably consistant readings. Average them together to get your "Benchline" estimate.



I have found that I really didn't need to go past 4th gear to get max HP reading. I think the G-Tech computes HP by max acceleration over time. Watch the G-Tech reading and when it peaks out, slow down, reset the unit, and make another run. It's been awhile but I think the unit stores the max reading.



I have had my truck Dyno'd and the results compared favorably with the numbers the little G-Tech provided. The G-Tech is really a great little device for establishing a "benchline" prior to making in mods, etc. What it can't do is provide you the dynamic data to create a chart similar to a dyno run.



Good Luck,



FDz