Minimum injector pulsewidth
Thread Starter
|
Former Vendor
Joined: Mar 2004
Posts: 4,362
Likes: 3
From: Hendersonville, NC
Minimum injector pulsewidth
Have a technical question for anyone with access to this information...
Does anyone happen to know what the minimum injector pulsewidth/max cycle rate is of the spool valves in the Siemens C95 injectors used in the 6.0?
(ms/us per cycle or # cycles per second; either one will work).
I'm trying to determine maximum engine RPM's that the stock injector spools will support within specification, and can't seem to find this information anywhere. Any help is appreciated.
Does anyone happen to know what the minimum injector pulsewidth/max cycle rate is of the spool valves in the Siemens C95 injectors used in the 6.0?
(ms/us per cycle or # cycles per second; either one will work).
I'm trying to determine maximum engine RPM's that the stock injector spools will support within specification, and can't seem to find this information anywhere. Any help is appreciated.
Cargo Master
Joined: Jun 2003
Posts: 2,203
Likes: 0
From: Carlsbad, California
I would think that you'd want to know both.
I was chasing some noise on my ham radio and did some work to figure out the frequency of injectors firing. At idle the injector for each cylinder fires once every 25 ms (40 Hz), cuising at 2200 RPM it fires every 6.8 ms (146.6 Hz), and at 4000 RPM it fires every 3.75 ms (266.6 Hz). I took an oscilloscope and and found pulse noise at frequencies that matched the expected idle and cruise values.
I didn't look for how long the injectors were turned on so I don't have any data on the duty cycle or pulse width.
I was chasing some noise on my ham radio and did some work to figure out the frequency of injectors firing. At idle the injector for each cylinder fires once every 25 ms (40 Hz), cuising at 2200 RPM it fires every 6.8 ms (146.6 Hz), and at 4000 RPM it fires every 3.75 ms (266.6 Hz). I took an oscilloscope and and found pulse noise at frequencies that matched the expected idle and cruise values.
I didn't look for how long the injectors were turned on so I don't have any data on the duty cycle or pulse width.
Thread Starter
|
Former Vendor
Joined: Mar 2004
Posts: 4,362
Likes: 3
From: Hendersonville, NC
Originally Posted by Daryl Hunter
I would think that you'd want to know both.
I was chasing some noise on my ham radio and did some work to figure out the frequency of injectors firing. At idle the injector for each cylinder fires once every 25 ms (40 Hz), cuising at 2200 RPM it fires every 6.8 ms (146.6 Hz), and at 4000 RPM it fires every 3.75 ms (266.6 Hz). I took an oscilloscope and and found pulse noise at frequencies that matched the expected idle and cruise values.
I didn't look for how long the injectors were turned on so I don't have any data on the duty cycle or pulse width.
I was chasing some noise on my ham radio and did some work to figure out the frequency of injectors firing. At idle the injector for each cylinder fires once every 25 ms (40 Hz), cuising at 2200 RPM it fires every 6.8 ms (146.6 Hz), and at 4000 RPM it fires every 3.75 ms (266.6 Hz). I took an oscilloscope and and found pulse noise at frequencies that matched the expected idle and cruise values.
I didn't look for how long the injectors were turned on so I don't have any data on the duty cycle or pulse width.
I had my suspicions that you'd be the first to post here
Thread Starter
|
Former Vendor
Joined: Mar 2004
Posts: 4,362
Likes: 3
From: Hendersonville, NC
Originally Posted by Tim Lamkin
need more data....
I could move it over to the SD forum for a bit and see who chimes in there
I could move it over to the SD forum for a bit and see who chimes in there
I'm probably the only person in the nearest 6 states that even cares
Can you copy it there without deleting it here?
Senior User
Joined: Aug 2003
Posts: 248
Likes: 0
Daryl,
I am missing something in your calculations, regarding injector firings. When I did theorectical calculations based on assumed idle speed of 700 RPMs, it appears to me that your numbers are "engine firing" frequency (8 times) , and not the frequency that one single injector fires.
At 700 RPM an individual cylinder will have 350 combustion strokes per minute. 350/60=5.8333 strokes/second. 1/5.833=.171438 or 171.4 ms cycle time. (Now in an 8 cylinder engine, some cylinder will fire every 21.42 ms, but any one injector will not fire that often.)
I think PSD wants to know just how fast he can make that spool valve shuttle back an forth.... Some obsession with more power.....
My guess would be that the info PSD wants is tucked away in some Ford/International engineers PC, cause somebody would have tested that, but I don't know why they would publish that info for the "public".
I am missing something in your calculations, regarding injector firings. When I did theorectical calculations based on assumed idle speed of 700 RPMs, it appears to me that your numbers are "engine firing" frequency (8 times) , and not the frequency that one single injector fires.
At 700 RPM an individual cylinder will have 350 combustion strokes per minute. 350/60=5.8333 strokes/second. 1/5.833=.171438 or 171.4 ms cycle time. (Now in an 8 cylinder engine, some cylinder will fire every 21.42 ms, but any one injector will not fire that often.)
I think PSD wants to know just how fast he can make that spool valve shuttle back an forth.... Some obsession with more power.....
My guess would be that the info PSD wants is tucked away in some Ford/International engineers PC, cause somebody would have tested that, but I don't know why they would publish that info for the "public".
Trending Topics
Senior User
Joined: Aug 2003
Posts: 248
Likes: 0
Addendum,
After reading pages 46 and 47 of the 6.0 bible again as a refresher, I have some additional thoughts.
It states that an 800 us pulse is required to open the spool and another 800 us pulse is required to close it. In between those pulses, you also need time for the injector to actually inject fuel. The time required to open and close the injector is 1.6 ms plus the time that the injector is injecting. I can't even guess what that time may be. I think that the limiting factor in upper RPM limits would be that amount of time required to actually spray fuel into the cylinder in quantities sufficient to produce power at those RPMs.
If my previous calculations are correct then at 4900 RPMs, the actual time for the piston to travel down on the powerstroke is 20.41 ms. That still allows a lot of time to fire an injector in comparison.
My guess is that you'll need to find ways to keep the moving parts inside the engine before you reach the limits of the injectors.
Don
After reading pages 46 and 47 of the 6.0 bible again as a refresher, I have some additional thoughts.
It states that an 800 us pulse is required to open the spool and another 800 us pulse is required to close it. In between those pulses, you also need time for the injector to actually inject fuel. The time required to open and close the injector is 1.6 ms plus the time that the injector is injecting. I can't even guess what that time may be. I think that the limiting factor in upper RPM limits would be that amount of time required to actually spray fuel into the cylinder in quantities sufficient to produce power at those RPMs.
If my previous calculations are correct then at 4900 RPMs, the actual time for the piston to travel down on the powerstroke is 20.41 ms. That still allows a lot of time to fire an injector in comparison.
My guess is that you'll need to find ways to keep the moving parts inside the engine before you reach the limits of the injectors.
Don
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
Cargo Master
Joined: Jun 2003
Posts: 2,203
Likes: 0
From: Carlsbad, California
dsweger, you're correct,
I went back and looked at my worksheet and that was for all 8 cylinders. Sorry about that.
Looking at only a single cylinder firing at 700 RPM idle speeds the injector will fire every 171.4 ms (5.8 Hz) as you said.
I went back and looked at my worksheet and that was for all 8 cylinders. Sorry about that.
Looking at only a single cylinder firing at 700 RPM idle speeds the injector will fire every 171.4 ms (5.8 Hz) as you said.
Thread Starter
|
Former Vendor
Joined: Mar 2004
Posts: 4,362
Likes: 3
From: Hendersonville, NC
Originally Posted by dsweger
Addendum,
After reading pages 46 and 47 of the 6.0 bible again as a refresher, I have some additional thoughts.
It states that an 800 us pulse is required to open the spool and another 800 us pulse is required to close it. In between those pulses, you also need time for the injector to actually inject fuel. The time required to open and close the injector is 1.6 ms plus the time that the injector is injecting. I can't even guess what that time may be. I think that the limiting factor in upper RPM limits would be that amount of time required to actually spray fuel into the cylinder in quantities sufficient to produce power at those RPMs.
If my previous calculations are correct then at 4900 RPMs, the actual time for the piston to travel down on the powerstroke is 20.41 ms. That still allows a lot of time to fire an injector in comparison.
My guess is that you'll need to find ways to keep the moving parts inside the engine before you reach the limits of the injectors.
Don
After reading pages 46 and 47 of the 6.0 bible again as a refresher, I have some additional thoughts.
It states that an 800 us pulse is required to open the spool and another 800 us pulse is required to close it. In between those pulses, you also need time for the injector to actually inject fuel. The time required to open and close the injector is 1.6 ms plus the time that the injector is injecting. I can't even guess what that time may be. I think that the limiting factor in upper RPM limits would be that amount of time required to actually spray fuel into the cylinder in quantities sufficient to produce power at those RPMs.
If my previous calculations are correct then at 4900 RPMs, the actual time for the piston to travel down on the powerstroke is 20.41 ms. That still allows a lot of time to fire an injector in comparison.
My guess is that you'll need to find ways to keep the moving parts inside the engine before you reach the limits of the injectors.
Don
Actual fuel delivery period won't be an issue; nozzles are available just as large as I want them; at higher injection pressure with large nozzles the delivery time will be minimal.
With 20.41 calculated time, I would imagine the stock spools will support any reasonable RPM that the engine internals would withstand. ~5000 RPM's is sort of my "goal", so I am coming to the conclusion that the injectors will be plenty sufficient. I can take care of the internal issues myself
I rarely see over a ~4ms pulse running an SCT tune, with more fuel still available. With larger nozzles this time would be very, very small...so once again not an issue.
Thank you
I'm glad to hear this- finding AFTERMARKET spools designed for such applications would most likely be impossible.
Senior User
Joined: Aug 2003
Posts: 248
Likes: 0
Also seems to me that I read in the "bible", that there are some conditions in the fueling strategy that actually fire the injectors more than once in a single power stroke ( Up to 3 times/stroke as I recall. ). My guess would be it is for emissions reduction ....That would certainly lead you to believe that you can cycle the injector a whole bunch faster than you need ( even to go really fast )......
FTE Leadership Emeritus
Joined: May 2004
Posts: 18,787
Likes: 30
From: Melbourne, Aus
Originally Posted by dsweger
Also seems to me that I read in the "bible", that there are some conditions in the fueling strategy that actually fire the injectors more than once in a single power stroke ( Up to 3 times/stroke as I recall. ). My guess would be it is for emissions reduction ....That would certainly lead you to believe that you can cycle the injector a whole bunch faster than you need ( even to go really fast )......
It is for many things, emissions, reduced noise, and economy.
You wouldn't want to cycle the injectors too often in one stroke though, as they would spend more time opening and closing, than actually delivering fuel.
The best way to do it in my experience would have around 3 openings in one stroke, and open the injectors at depreciating times.
e.g. 1st opening 2ms
2nd opening 1ms
3rd opening 0.5ms
That would be something to work with, and refinement would be required on the dyno.
Thread Starter
|
Former Vendor
Joined: Mar 2004
Posts: 4,362
Likes: 3
From: Hendersonville, NC
Originally Posted by Daryl Hunter
Who makes the injector? It would be nice to pull up the specs for the unit itself.