conversion of injector pulse width to duty cycle?
conversion of injector pulse width to duty cycle? How do I convert injector pulse width to duty cycle?
I have the lookup tables, but I'd like it calculatable so I can graph some things against each other.
thanks
I have the lookup tables, but I'd like it calculatable so I can graph some things against each other.
thanks
so based on the equation posted by humipinss, i made two graphs for two different situations:
RPM vs Pulse Width
and
RPM vs Duty Cycle
hope that comes in useful for someone,
Marcin
RPM vs Pulse Width
and
RPM vs Duty Cycle
hope that comes in useful for someone,
Marcin
can anybody post a spreadsheet that I can plug #'s into???
and what #'s do I use to get the injector pulses for my entire engine plot like that...
I could probably make a spredsheet myself if I knew where to get a full table of my injector pulses........
I have HPTuners by the way
and what #'s do I use to get the injector pulses for my entire engine plot like that...
I could probably make a spredsheet myself if I knew where to get a full table of my injector pulses........
I have HPTuners by the way
yes... but you didnt answer any of my questions..all you did was add this post toa sticky...doesnt tell me anything about where to get the info I need so I can plug it into the equation.....
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TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
Originally Posted by soundengineer
yes... but you didnt answer any of my questions..all you did was add this post toa sticky...doesnt tell me anything about where to get the info I need so I can plug it into the equation.....
As for where to get the info... your scanner... log injector pulse width and then use the formulas that are listed... IPW will be in seconds, you just need to log RPM, and IPW ... 1200 is a constant
http://www.transamws6.net/HPTuners/injpwcalc.xls is the same thing that's been posted for download
RedHardSupra: hope you don't mind me duplicating it... I added credit to you in the beginning of the file (was kinda fun setting it up.. I've never used absolute $ cell references and conditional shading before)
Last edited by horist; Apr 21, 2005 at 12:06 PM.
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Verdad Gallardo hey Horist, thanks for a sticky!
and no, of course i don't mind, and thanks for giving credit where credit's due.
if you want more excel tricks, look at the MAF calibration spreadsheet, that has some rather advanced concepts like array formulas.
where in IL are you? I don't know anyone local that tunes stuff, i'd love to buy you a beer and pick your brain.
PM me if you're intersted.
Marcin
and no, of course i don't mind, and thanks for giving credit where credit's due.
if you want more excel tricks, look at the MAF calibration spreadsheet, that has some rather advanced concepts like array formulas.
where in IL are you? I don't know anyone local that tunes stuff, i'd love to buy you a beer and pick your brain.
PM me if you're intersted.
Marcin
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
I'm up a bit north of you near Wauconda/Lake Zurich area
as for the 1200 constant... did a quick search and Paul@EfiLive explained in the past
as for the 1200 constant... did a quick search and Paul@EfiLive explained in the past
rpms (revs per millisecond) = rpm/60000
maxpw (maximum injector pulse width) = 2/rpms (2 revolutions to complete 4 stroke cycle)
injdc (injector duty cycle) = injpw*100/maxpw
so...
injdc
= (injpw*100)/(2/(rpm/60000))
= (injpw*100)/(120000/rpm)
= injpw*rpm/1200
That's where the 1200 comes from
maxpw (maximum injector pulse width) = 2/rpms (2 revolutions to complete 4 stroke cycle)
injdc (injector duty cycle) = injpw*100/maxpw
so...
injdc
= (injpw*100)/(2/(rpm/60000))
= (injpw*100)/(120000/rpm)
= injpw*rpm/1200
That's where the 1200 comes from
On The Tree
Joined: Jan 2002
Posts: 107
Likes: 0
From: Round Rock, TX
Originally Posted by horist
I'm up a bit north of you near Wauconda/Lake Zurich area
as for the 1200 constant... did a quick search and Paul@EfiLive explained in the past
as for the 1200 constant... did a quick search and Paul@EfiLive explained in the past
6000 RPM = 100 revolutions per second
1 revolution = .01 seconds (or 10ms)
2 revolutions = .02 seconds (complete 4 stroke)
How long is the intake valve open? If the injector is spraying for 15ms, doesn't it have to be spraying while the valve is closed?
i was trying to figure out pulse width fuel vs air % to try and see where i stand for tuning my injectors, if anyone has some idea on this iwould like to know, i tried earlier but never finished
some more poking at injector duty cycle, but this time it's used for getting your volumetric efficiency too 
http://redhardsupra.blogspot.com/200...olumetric.html
http://redhardsupra.blogspot.com/200...olumetric.html
Restricted User
Joined: Apr 2005
Posts: 14
Likes: 0
From: SOCal
Originally Posted by RedHardSupra
How do I convert injector pulse width to duty cycle?
I have the lookup tables, but I'd like it calculatable so I can graph some things against each other.
thanks
I have the lookup tables, but I'd like it calculatable so I can graph some things against each other.
thanks
Here's another method:
Inj PW/ [{1/RPM}*120]=Inj Duty %
Great graphs by the way guys....
There are lots of ways to get there....just depends which road you like! LOL
wouldnt it be easier to say
Inj PW / (120/RPM) = Duty
or
Inj PW x RPM / 12 = Duty
remember injector pulse width in th eformula here is in seconds....
so 2.5 miliseconds = .025
Inj PW / (120/RPM) = Duty
or
Inj PW x RPM / 12 = Duty
remember injector pulse width in th eformula here is in seconds....
so 2.5 miliseconds = .025
Last edited by soundengineer; May 12, 2005 at 11:52 PM.
