I'd like to find a program that would produce torque curves for my car in each gear. Ideally, I would just enter the torque figures at 100 rpm intervals, tell it the gear ratios at which the measurements were taken, and the gear ratios for my transmission, then it would plot the torque curves for each gear. I know that this could be done with a generic math program, plus some effort, but I am sure there is something like I am describing, I hope for free.


[Modified by Charles Klein, 3:42 PM 12/2/2001]

 

Drag2000 is a software package that can take a torque data along with gearing, tire size, shift RPM, etc and give you 1/4 mi data, i.e. time slips. You can optimize both TC stall and shift points for best trap speed. It also shows how much of the 1/4 mi you spend in each gear with RPM plots.

It is made by Motion Software, Inc, cost about $50 and comes on CDR. If interestedk, try http://www.amazon.com/ software section.

 

That software looks great. I could not find it at Amazon, but they sell it for $50 at http://www.motionsoftware.com. For another $40 you can get Dyno2000 and CamDisk2 which includes 718 cam profiles for simulating small-block Chevy engine configurations.

 

Check this out...
http://www.prestage.com/carmath/dynochart.asp

I learned that my first shift is at 4600, and the rest at 4400 to maximize my power. It works...

 

Tells me 6400 ,6400 & 6200 Damn and I shift @ 6250 and 5900


[Modified by L98Terror, 8:19 PM 12/2/2001]

 

LOL. You install that radiator yet?

 

No it's been to nice out

 

Thanks Scorp. Very nice, and interesting. It recommends 6400 for all 5 shifts for my LT4. I think my graph is typical. I wonder how many guys with stock LT4s shift at 6400 (at the fuel cutoff, tehnically 100 rpm past redline). This is also 500 rpm past peak horsepower. The standard advice to shift at peak horsepower. So far I agree with the results, but I'm not sure their algorithm accounts for everything that's in the data.

 

Right, so when you shift, the RPMs will drop and be closer to peak horsepower again. :)

 

When you shift, don't you want the rpms closer to peak torque? I tried that web page out Scorp, and on my dyno run, I don't have any info past 5200 RPM, the guy never ran it past that point. It said shift @ 5200, @ 5200, @ 5200. Maybe if I had any info past that point, it'd be a bit more accurate. Just fooling around with my G-Tech, I got my best run shifting @ 5800, @ 5600, @ 5600. I just got it into 4th for about 1.5 seconds or so before it calculated the 1/4 for me. With me and my brother it said we ran a 13.6 @ 110 with me chirping the tires going into 4th!! One run I ran it up to 6300 RPM in first just to see. It didn't pull any harder, so I'm never doing 6300 again!!

By weight on some corvette web page +me +my brother = 3780 lbs.
Yeah, we ain't small. :D


[Modified by black_89_vette, 1:25 AM 12/3/2001]


[Modified by black_89_vette, 1:25 AM 12/3/2001]

 

Charles Klein, there two reasons to stay in a gear past peak HP:
1) maximize the overall HP under the RPM vs HP curve between shifts.
2) stay in the lower gear longer (more RW thorque).

 

I took dyno run and did some graphing in Excel.

To create this I used the data I got from StreetDyno when measuring RWHP and RWTQ without supercharger.

Top graph shows the 'normal' dyno graph with a yellow RWTQ curve and a blue RWHP curve. This is my baseline run without supercharger ( stock engine ).


246 ft-lbs @ 3000 RPM
186 hp @ 4180 RPM

That RWTQ number is actually false. What you measure is RWHP. Then you plot that against engine RPM, not wheel RPM. HP numbers will bw the same, but the tourqe will not! With a 3.07 rear end you must multiply the tourqe number with 3.07 and divide the RPM number with 3.07 to get the 'real' RWTQ numbers.

So, using a th700r4 and a 3.07 rear end the correct numbers would be:

1:st gear (3.07*3.06)
RWTQ = 2311 ft-lbs @ 319 RPM
RWHP = 186 hp @ 445 RPM

2:nd gear (3.07*1.62)
RWTQ = 1223 ft-lbs @ 603 RPM
RWHP = 186 hp @ 840 RPM

3:rd gear (3.07*1.00)
RWTQ = 755 ft-lbs @ 977 RPM
RWHP = 186 hp @ 1362 RPM

4:th gear (3.07*0.70)
RWTQ = 529 ft-lbs @ 1396 RPM
RWHP = 186 hp @ 1945 RPM

Rear wheel RPM is actually speed.
On the lower graph RWHP (blue) and RWTQ (yellow) is plotted with speed (MPH) as X-axes. RWTQ numbers on the left and RWHP numbers on the right.



To get maximum acceleration you should use the gear that gives you the highest rwtq /rwhp. Optimum shift-points are where the curves intersect.

The cyan curve is an attempt to calcuate hp required to overcome drag at different speeds. Top speed is where that curve intersects the blue hp curve.

Did I manage to confuse you all now ?




[Modified by JoBy, 8:26 PM 12/5/2001]