Hi,

I am using UpREV chiper as Engine interface and logging

In log I found a crazy information.

As Chiper manual describe, Ignition Timing is express in milliseconds Before Top Down Centre (cvs column is "IGN TIMING (BTDC)").

To convert it on degrees I use this simply formula:

Degrees = TA / ms_for_360_degrees * 360
Degrees = TA / (1/RPM * 60 *1000) * 360

Now, in Excel appears only non suitable values like >180°.
Example:in a row of .cvs file I read TA = 28ms, RPM=1100 that result 184°!

Someone has experienced in conversion from ms in TA to Degrees?
(or where is my mistake!)


Note: If the time indicate the time to Max Pressure it is also wrong.... ....in degrees normally it is 15° to add to TDC.

Thanks

 

Post more of the log or the whole thing. I'll see if I can figure it out.

 

Could this be a radians vs. degrees conversion issue? I can't recall what Excel defaults to.
2pi radians = 360°

 

No,

The log shows milliseconds to TDC, or I think UPrev Chiper shows this...

Now, the log shows also actual RPM.
To convert it on degrees I use this simply formula:

Degrees = TA / ms_for_360_degrees * 360
Degrees = TA / (1/RPM * 60 *1000) * 360

or if you prefer

Radiants = TA / ms_for_one_turn * 2PI
Radiants = TA / (1/RPM * 60 *1000) * 2PI

....and the conclusion is TA>180° or TA>PI that it's no possibile...

This is the problem!

 

Hmmm. I see that and I got the same result using the same idea of formula, so I'm not sure where the error is.
(28ms)(1100 rev/min)(360°/rev)(1min/60000ms) = 185°

 

At 1100 rpm, you only have 54.54 ms per rev and the ignition fires on the second revolution of the otto cycle. 1100 rpm divide by 60 equals 18.33 revs per second, then invert it to get 0.05454 sec per rev. Therefore it is impossible to have 28ms ignition before tdc if you assume time before tdc references at 360 degrees.

Let's say in theory that Nissan engineers reference that time at 45 degrees before tdc. So your formula becomes:

23.1 degrees = TA / (1/RPM * 60 *1000) * 45

If you were to reference at 90 degrees, it doesn't make sense either.

46.2 degrees = TA / (1/RPM * 60 *1000) * 90

BTW, 15 degrees is only when the engine is completely warmed up and at normal idle, not cold idle.

The only way to know exactly is to disassemble the ecu code completely, so this is a good start to think about.

 

But either ways, ms or degrees, tuning it becomes the same, since they are directly proportional. Little to no difference. Listen for knock digitally or with headphones.

 

This is just a good starting point! ...now I search some confirmations...

The best is that UpREV describes where the TA parameter is extracted in their software and whats it mean....

I write a post in UpREV site, but I didn't received any reply


P.S. sorry for my bad english, I am Italian and I studied it a long time ago!

 

Your English is good enough that you shouldn't even have to apologize by today's standards. I work with this phony a$$hole who claims to be fluent in 5 languages. If I interviewed him, he'd have been out the door in 10 minutes, but he got hired. He is persian but he moved here from Texas. Yesterday, the gifted linguist is asking someone in the mail room "how for you pronounce the names J-U-A-N?" Seriously!!? This guy claims to be from Texas and this is the first Juan he's come across?! Man, I can't wait until he's gone.
/rant
I hope you figure out your tuning issue.