GM offset vs. Ford offset

[chevyalltheway]

You still have your updated info? I was trying to get my spreadsheet right but Greg said my biggest problem is my offset is ford based. I'm still learning but would like to see where you were going with the data.

[Alvin]

Yeah, I finished it and its working well. I can answer any questions you might have against how ford and GM describes their injectors. To be frank the Banish Data is not in the ball park and I know other tuners have noticed this between the error you have dropping known injectors in otherwise stock cars.

If someone tells you that you can get true GM data from Ford they are lying. The difference in the base fuel pressure basically puts us off the map. To counter this the sheet I made is live and a human must make a decision on how to extrapolate the data beyond points given. So in other words you must decide 1st.. 2nd... nth order fit to what is given per Ford table.

[Pulse_GTO]

Is the link still valid?

[DSteck]

Which injector are you trying to convert?

[Pulse_GTO]

Ford green tops.

[TheBritishColumbian]

I just attempted to make my own sheet. Referring to the original graph posted, I solved using some good old high school definitions for a line y=mx+b where m is the slope and B is the y intercept. My Y axis is the Delivered Fuel, my X is Time, just as the graph shows.

I was able to solve for b using by using the low slope value for m, and the data point (Offset Ford, 0). This allowed me to fully define the Ford Low Slope Line equation. Knowing that the low slope and high slope share a value at the break point, I used this equation and the break point fuel delivered to solve for the time in ms when the break point occured. I now have a second shared point (BKPT Vol, BKPT Time). As I said since this point is shared between the two lines I could then fully define the high slope equation. Using the high slope line equation I solved for the x intercept. This should be the new GM offset, when Fuel Delivered = 0 the offset = ____. I just want to check my thinking. The values ended up being very close.

If my typed explanation is hard to follow I can take a picture of my paper notes.

Can someone please check my work. Ford to GM Offset Conversion.xlsx

[DSteck]

Your approach is correct. Have fun with short pulse adder.

I posted a spreadsheet on the forum that automatically does this and fits it to GM axis labels.

[TheBritishColumbian]

I saw you had posted one but I couldn't find yours. For some reason no one runs short pulse adders on the LSJ P12. I can't find an example of them being used in any repository files.

I did build a wicked one for interpolating and converting to the P12 columns for VAC and MAP too but I'm going to keep that one close for a bit. I'm a little bitter the injector seller would not supply the information.

[DSteck]

It's probably because it doesn't exist. ID is the only injector company worth a damn.