EE Speedometer correction spreadsheet with tire size calc

[95_C4]

I modified the EE speedometer calibration spreadsheet for the 90's model B/F/Y body GM cars and have attached it. You can input your metric tire size (eg 275/40-17) and it will calc the revs/mile. The instructions are on the face of it.

Not sure if this is the right section to post, if not please move the thread.

UPDATE: Spreadsheet has more tabs for other calcs and has been renamed, original file deleted for clarity. Speedometer correction fields added for too slow or too fast to change tire diameter. Added functions include calculators for displacement increase, ethanol gas, and fan temps. I also included the website to enter your VIN & get the original calibration ID. Sheet is color coded, Green= Data you enter, Blue= Calculated data, Yellow= Info only.

UPDATE 2: Clarified the displacement percent field, and limited it to 4 decimal places. I made it read like this in the event the user wants to multiply (or reduce) a table by a certain amount. A 9% increase here will be shown as 1.0900, not 9.0000. If displacement is reduced, the same applies, for example a 350 destroked to 340 CID would show as .97xx.

I will keep the latest version of the spreadsheet in this post.

[johnny_b]

do you have a formula to correct for MPH error based off current settings?

I have used several spreadsheets to try and get speedometer settings, and I always end up about 2 MPH off when checked with a GPS speedometer.

[skandolis]

Appreciate the time, doesn't seem to work for me, i can't input aspect ratio. For tire size (275/60/15) as soon as i finish typing in the 60, it automatically changes to 6000%
maybe i'm doing something wrong....(i am spreadsheet dumb..............) or possibly a problem with open office..........

[95_C4]

do you have a formula to correct for MPH error based off current settings?

I have used several spreadsheets to try and get speedometer settings, and I always end up about 2 MPH off when checked with a GPS speedometer.

I'm not sure how that is addressed in the Tuner Pro program. I just added a calc field to the existing spreadsheet. You should be able to workaround the problem via tweaking the tire size to adjust for the 2 MPH. If your speedometer reads too slow, try reducing the tire diameter to increase the revs/mile. If it reads too fast, then try increasing the tire diameter to decrease the revs/mile.

[95_C4]

Appreciate the time, doesn't seem to work for me, i can't input aspect ratio. For tire size (275/60/15) as soon as i finish typing in the 60, it automatically changes to 6000%
maybe i'm doing something wrong....(i am spreadsheet dumb..............) or possibly a problem with open office..........

I wrote it using Libre Office (free software, similar to Open Office) and saved it as an Excel file. I tried it in Excel 2003 and it worked properly. If typing in 60 yields 6,000, try typing in .6 and see if that fixes the problem.

I'll attach the Libre Office (.ods) version, see if it works in Open Office.

[skandolis]

the .ods version acts the sames as the .xls version however using .60 instead of 60 for the aspect ratio corrects the problem and works out to a tire diameter of 27.99 which is very close to the 28.0 diameter advertised. thanks again

[95_C4]

As I look through Tuner Pro, I have revised the spreadsheet to include calcs for CID (larger engine e.g. stroker), ethanol gas, and fan temps (Celsius to Fahrenheit & vice-versa). I also have an info only tab with the website to look up your calibration ID by VIN.

I have updated the speedometer tab by including a calc for over/under tire size to correct too slow or too fast speedometers, and incorporated the .4 vs 40 percent data entry.

Color coding is updated as well: Green= data you enter, Blue= data that is calculated, and Yellow= info only.

The file has been renamed Tuner Pro Field Mods.xls. See first post for spreadsheet.
EDIT: I will update the first post for the spreadsheet so there are not multiple editions in the thread.

[johnny_b]

Thanks, sheet looks great. I'll give it a try.