Spreadsheet Shift point calculation

[Mr Beau]

I seem to remember seeing a spreadsheet that calculated optimum shift points. You would input your engine performance data and gear ratios, and then the spreadsheet would calculate the optimum shift points. It had a macro or something that did all the calcs. Does anyone know what I'm talking about??

I've done a search and have come up empty.

Thanks.

[ErVikingo]

I have something somewhat similar to what you are asking for but its for 901 boxes. If you give me data on your tire size, torque & HP figures by rpm (every 50 or so RPM increment), final gear ratio and gear ratios, I think I can work it out.

Should be fun ! Let me know

[bigrubberjeep]

I think I can help, I have 2 spread sheets, PM me your emial and I will send it.

[Adam]

I've just made a very easy-to-use one for 915s which is in .XLS format. It not only generates the data, but it also plots a graph showing RPM over Speed.

If somebody can host it, I'd be happy to share it.

[rdane]

carquip.com under 915 gears for sale

[Mr Beau]

Just to clarify, I'm not looking for a spreadsheet that just shows the speed in gears, but one that allows you to input the hp curve of your engnie and calculate the optimum shift points. I'm sure I've come across it, but I can't seem to find it now.

[bigrubberjeep]

Originally posted by Mr Beau
Just to clarify, I'm not looking for a spreadsheet that just shows the speed in gears, but one that allows you to input the hp curve of your engnie and calculate the optimum shift points. I'm sure I've come across it, but I can't seem to find it now.

I thaught redline was optimum!

(J/K)

[Bill Verburg]

Is this what you are looking for

You will need your gearing and tire size

[Bill Verburg]

Optimum shift points are (generally) just past the hp peak

[Mr Beau]

Nope, not exactly what I'm looking for. It's an Excel spreadsheet.

Regarding optimum shift points, it will be somewhere between HP peak and redline. It varies depending on the HP curve and gear ratios, and the optimum point isn't necessarily the same for each gear.

[David]

I found this spreadsheet rather interesting. I haven't taken time to check their math, plus it's protected: http://www.offroadvw.net/exceldyno/

[imcarthur]

David

That is one cool spreadsheet.

Just have to gather all the data to make it work . . .

Thanks

Ian

[Bill Verburg]

I did something similar w/ available thrust at the rear wheel vs rpm or speed. You do need dyno #s as well as the gearing and tire #s

Regarding optimum shift points, it will be somewhere between HP peak and redline. It varies depending on the HP curve and gear ratios, and the optimum point isn't necessarily the same for each gear.

If you have the time to look for the mathematicly precise point your not paying attention to more important information.

[304065]

The ideal shift point? Just after you've pulled in front of the guy you're passing and before the rev limiter kicks in.

Bill, that's an interesting graph, can you tell us more about it?

[widebody911]

Sounds like something that would be easy to code in a perl cgi script