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Electronic Fuel Injection Tuning Forum
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Tomak
Joined: 20 Apr 2008
Posts: 429
Location: •Calgary •Alberta
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 Posted: Tue Jan 17, 2012 9:33 am Post subject: |
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| mrx wrote: | | jalai wrote: | | Don't look at the PW, this is not important value. Minimum controllable (linear) fuel flow is significant. |
I understand... can someone tell me which is this minimum amount of controllable fuel flow for the 720cc ID and 1000cc ID? and which effective PW would this result for example @ 43psi fuel pressure? |
Not sure about ID. But all Bosch type injectors do have a "minimum usable PW".
This is minimum PW that the injectors can supply repeatable stable fuel delivery. (NOTE, this is different than the "linearity" we are talking about). This is a pulse to pulse variability at low pw's, as typical flow testing is not done with one pulse, rather, they average fuel volume from a full cycle of pulses. Basically, though the average at low PW may "look" stable", the standard deviation of each individual event become more and more erratic at very low PW's.
I assume the ID's do have a "minimum usable PW" as well, since it appears to be a modified Bosch injector.
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MrDomino
Joined: 01 Oct 2009
Posts: 188
Location: Indianapolis, IN
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| Posted: Tue Jan 17, 2012 9:47 am Post subject: |
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Exactly. Whenever pulsewidth reaches a critical minimum the standard deviation of the mass of fuel per injection goes way up.
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APEX Speed Technology
Joined: 13 Nov 2004
Posts: 726
Location: Venice, CA
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| Posted: Wed Jan 18, 2012 8:10 pm Post subject: injectors |
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| Quote: |
I assume the ID's do have a "minimum usable PW" as well, since it appears to be a modified Bosch injector. |
Remember though - this isn't about just the hardware. The main points are:
1. Consistency between injectors AFTER BREAK-IN.
2. Consistency between injectors for offset.
3. The data provided by the manufacturer that allows for more consistent running at low loads.
Unmodified, OEM injectors tend to have these pretty well worked out. Modified aftermarket injectors tend to not. ID is one of the few people I know who goes through the trouble of break-in, offset balance and offset vs. pulsewidth data.
-Neel
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Neel Vasavada
Apex Speed Technology
2947 S. Sepulveda Blvd
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www.apexspeedtech.com |
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Power-Tripp
Joined: 26 Nov 2008
Posts: 311
Location: Alabaster, AL, USA
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| Posted: Sat Jan 21, 2012 7:33 am Post subject: Re: Injector information |
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A good read Neel.
| APEX Speed Technology wrote: |
| Quote: | | ow do you guys time the injections? One of the cold start emissions papers I read said that once the intake valve is warm the best atomisation comes from spraying the fuel directly on the intake valve when it is closed. |
There are several methods. Sometimes, plain empirical testing yields the best results. Other times, you can start by spraying on a closed valve for atomization.
But remember, its not just about atomization, its also about avoiding reversion.
-Neel |
There is also a large difference between the results with single injectors spraying directly at the back of the intake valve, and secondary staged injectors located higher in the inlet track or in shower-form for use at higher engine speeds. The benefits to output and reduced BSFC with staged injection should not be overlooked.
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APEX Speed Technology
Joined: 13 Nov 2004
Posts: 726
Location: Venice, CA
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| Posted: Mon Jan 30, 2012 8:59 am Post subject: emperical testing |
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| Quote: | | There is also a large difference between the results with single injectors spraying directly at the back of the intake valve, and secondary staged injectors located higher in the inlet track or in shower-form for use at higher engine speeds. The benefits to output and reduced BSFC with staged injection should not be overlooked. |
Agreed. There are installations that benefit from secondary injection and those that don't. The standoff and management of manifold wetting with showerheads and secondary injectors present their own set of problems. Another reason why starting with a good, consistent, easy to manage injector makes life so much easier.
-Neel
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Neel Vasavada
Apex Speed Technology
2947 S. Sepulveda Blvd
Los Angeles, CA 90064
310-314-2005
www.apexspeedtech.com |
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