Where to Shift Based on Dyno Graph?

[oldschool85]

What rpm and mph should I set the shift points in HP Tuners based on dyno graph?

LS1, Patriot LS6 Heads,224/224 .581 Cam,Fast 90/90,Headers,
Stock Automatic(3600 Stall),3.27 Rearend.

[Higgs Boson]

6750, calculate the mph yourself based on that. It depends on what gear you are in also, as you want the rpms to drop into peak torque and how far they drop depends on the trans gearing.

[oldschool85]

They are set at 6000 rpm.... I believe it is shifting too early.. Any suggestions?

[Fast9C1]

First off, nice curve. Most folks never get one that flat no matter how hard they try. BTW, what happened at 6400? It's smooth as silk up there to there and then a weird little kink with an associated AFR change.

6k is way too early. You just need to do the math like HB already suggested. There are volumes written on shift point tuning (Google is your friend). The basic idea is to keep the engine as high in the power curve as possible all the time.

[Montecarlodrag]

The way I see it, from 5700 to 6400 power output doesn't increase more than 15 HP.
I think 5900-6000 is a good shift point, there is no sense revving it higher.
I'd use the tune file from the blue run.

[Higgs Boson]

The way I see it, from 5700 to 6400 power output doesn't increase more than 15 HP.
I think 5900-6000 is a good shift point, there is no sense revving it higher.
I'd use the tune file from the blue run.

Whatever puts him back around 5200 RPMs after his shift. The shift point will be different for each gear.

[jimmyblue]

Tell us what RPM you see after upshift, WOT (shift extension) and
then it'll be clear enough to draw you a picture.

[Fast9C1]

Bruce Bowling wrote a nifty calculator (hence the Google is your friend comment above...it comes up first in a search):
http://www.bgsoflex.com/shifter.html

Assuming it's a 4L60 with it's dreaded ratios I took the liberty of assuming that 6400 rpm kink is some kind of fuel issue (that can be easily corrected) and extended the curve straight to 6500:

Bowling's Optimum Shift Calculator

Input Parameters Are the Following:
Transmission Ratio One = 3.06 to 1
Transmission Ratio Two = 1.62 to 1
Transmission Ratio Three = 1.00 to 1
Transmission Ratio Four = 0.70 to 1
Horsepower = 190 at 3000 RPM
Horsepower = 235 at 3500 RPM
Horsepower = 280 at 4000 RPM
Horsepower = 325 at 4500 RPM
Horsepower = 360 at 5000 RPM
Horsepower = 390 at 5500 RPM
Horsepower = 400 at 6000 RPM
Horsepower = 400 at 6500 RPM
Computation Results:

Using the Criterion for Maintaining the Same Horsepower Before and After Shift:

Finding Best Shift Placement Points For Ratio 3.06 to 1.62: Error: Search outside range - need more RPM range in HP table! Finding Best Shift Placement Points For Ratio 1.62 to 1.00: Error: Search outside range - need more RPM range in HP table! Finding Best Shift Placement Points For Ratio 1.00 to 0.70: Error: Search outside range - need more RPM range in HP table!

Maximumizing the Area Under the Horsepower Curve:

Finding Best Shift Placement Points For Ratio 3.06 to 1.62:

Found optimum shift RPM at 6494, which achieves maximum area under horsepower curve, and lowers the RPM to 3450 after shift
Finding Best Shift Placement Points For Ratio 1.62 to 1.00:

Found optimum shift RPM at 6492, which achieves maximum area under horsepower curve, and lowers the RPM to 3995 after shift
Finding Best Shift Placement Points For Ratio 1.00 to 0.70:

Found optimum shift RPM at 6494, which achieves maximum area under horsepower curve, and lowers the RPM to 4520 after shift

Pretty easy to see why the 4L80 conversions are so popular

Of course, this only tells the story from the point of view of the input shaft on the trans. Your converter will make up for a bit of the gear change losses.

[oldschool85]

My shift rpm & mph are set as follows: I have a 2000 Stock LS1 Engine(Heads and Cam),3600 Stall,Stock Automatic Trans,3.27 Rearend.

My question Is my shift rpm and mph correct for a 6300-6400 Shift?


Shift rpm : 1-2 6000 2-3 6000 3-4 5900

Shift mph: 1-2 45mph
2-3 83mph
3-4 128mph
2-1 42mph
3-2 81mph
4-3 127mph

[Fast9C1]

You can figure out the gear-rpm-mph relationships with any of the many online calculators (hint: if they only give you a rear gear option, you can simulate any trans gear by multiplying the trans ratio by the rear ratio). That is pretty straightforward, but again, it only tells the story from the point of view of the tranny's input shaft. Nobody can predict what the actual engine rpm is going to be because of your torque converter. That introduces multiple variables at every engine speed.

If 6400 is the true rpm ceiling on your engine and you want to achieve shifts right around there, the only way I can see is some trial and error with data logging. Once you have that nailed down and you are interested in taking it to the track, you will probably find that the car will keep going faster if you keep raising the shift points...right up until you hit valve float

EDIT: As I was typing that, I was thinking to myself "...would sure be nice if my old calculator was still online..." and then I figured, it might still be. I dismantled the old website many years ago, but apparently kept the calculators online:
http://www.scottknight.com/calculators/js_tire.html