Simple SOI calc excel spreadsheet.

So we have SOI as degrees BTDC.
If we increase values in SOI map we inject earlier, right?

Correct.

Hi there,

Please could some one explain exactly what this tool is called and how it works?

Sorry for the seemingly stupid question :?

Take a look ;)

Hi Alex,

AWESOME -- thanks alot, i needed to understand what SOI meant, now that i do, it makes sense.

Thanks alot

Good tool - but for a rough guide only. To be mega accurate, you'd need to take into acocunt the stroke and rod length in the spreadsheet for each induvidual engine. ;)

(Remember that piston motion is a sine wave, dwell at TDC and piston acceleration and hence speed around TDC depends on stroke and rod length. This calculator can surely only calculate the "average" piston speed and hence degrees per second.)

Lot's of thanks!

Can't wait to check out the file to get an idea where I should adjust my SOI.

Hi,

I made an extra worksheet in this file - maybe it can help others. It is to calculate the EOI ATDC (End of Injection, Degrees After Top Dead Centre). It is a simple formula but it is more to help beginners (like me)...

How to use:

• Download & Open file.
• Select EOI Calc tab/worksheet
• Enter your SOI in Degrees BTDC (EDC15C2 SOI Maps are in this standard) for each RPM (1st blue boxes)
• Enter your Injection Duration in uSec (You calculate this from Rail Pressure & Injector Duration maps for each IQ you want to test) for each RPM (2nd blue boxes)
• Result is in orange box

Positive numbers are how many degrees after top dead centre your injection will finish.
Negative numbers indicate your injection will finish before top dead centre. This is not good!