Greg Fell

iTrader: (9)

I'd like to get some more feedback, so I am posting here as well.

https://ls1tech.com/forums/showthrea...82#post2917682

This is a work in progress, it is not certified as correct (yet?)

The basic theory of this is, I'm assuming that the best shift point is the max area under curve for a given RPM range.

I was surprised to see the values I came back with were much higher than what I assume my shiftpoints should be. I may be missing something, theory wise, but I cant grasp it right now if so.

There are 2 known flaws with this, one small (point 1) and one that probably would be a factor (point 2).
1.) i take the bottom rpms (rpms after a shift, ex 1/2) and compare to your dyno curve and if it is greater than or equal to, i use it. However, my RPM increments are by 100, instead of 1's. Arguably, if my lower (after shift) rpm is 4401, I should use 4400, right now I use 4500.

2.) 4th gear may not be wound out to the top, so the 3-4 shift may be different than the 1-2, 2-3.

Feedback is welcomed. Maybe there is a tool like this already. At any rate, I just wanna go fast, so if there isn't we can use this after it is deemed accurate. Right now I am not confident it is, my calculated shift point is much higher than I expected and was told it should be.

Adrenaline_Z

From a quick glance, it seems you are shifting too high in first.

I'm assuing the green highlighted box is your shift point?

If peak HP occurs at 6100 RPM, then you want to select a shift point of about
6700 RPM which will set you back at about 4800 RPM on 2nd gear.

That will give you the best 'area under the curve' according to those numbers.

I haven' plotted the graph, but it seems fairly close.

The trick is to "straddle the curve". Shift at the RPM that gives you as much
power over the peak, as it would on the next gear RPM.

Greg Fell

iTrader: (9)

Could you explain more?

I am not 'using' this yet, just trying to get her ironed out. 7000 RPM does seem too high to me, as well, I just want to fully understand the logic so I can adjust and create something useful.

Of course, it is pretty easy to just go to track and experiment too. But that is only fun on the weekends when you are actually there!

99zman

iTrader: (23)

[/QUOTE]If peak HP occurs at 6100 RPM, then you want to select a shift point of about
6700 RPM which will set you back at about 4800 RPM on 2nd gear[QUOTE]
Now thats some slow shifting...

Adrenaline_Z

Best way I was taught was to plot the graph, or use your spreadsheet columns B and D.

Cut out a rectangle in a piece of paper that spans about 2000 RPM.

2000 RPM represents your shift window between 1st and 2nd gear.

Place the cut-out paper on your plotted graph, or spreadsheet columns.

Move the hole in the paper until you see the highest two points of the
graph within the window...

or

Move the hole in the paper until you see the highest two numbers in your
spreadsheet columns.

IE:
A 2000 RPM shift window shows:
6700 RPM = 435 HP shift point in 1st
4700 PRM = 408.51 HP 2nd gear RPM

If you move the hole in paper to 7000 RPM:
7000 RPM = 300 HP shift point in 1st
5000 RPM = 432 HP 2nd gear RPM

It's tough to see the average with numbers, but you can see the time wasted
above 6700 RPM has less power than the power you would get by hitting
2nd gear at 4700 RPM.

Does that help?

EDIT - By the mathematical method, you could add power columns at each
RPM interval and compare the results between different shift points.

The highest total power over the shift window will translate to the quickest
acceleration.

Adrenaline_Z

But that's a faster car in the 1/4 mile based on the power curves.

Greg Fell

iTrader: (9)

If peak HP occurs at 6100 RPM, then you want to select a shift point of about
6700 RPM which will set you back at about 4800 RPM on 2nd gearI don't think he means he is going to wait til his RPMS drop to 4800. After the shift is done, it will be at 4800, in his example.

Greg Fell

iTrader: (9)

I have updated the spreadsheet some, it takes into account intervals now.