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Fuel injectors



 
 
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  #1  
Old August 20th 05, 04:23 PM
Dirtroadie
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Default Fuel injectors

I have been searching but have not been able to find information
relating to the difference in electrically operated fuel injectors.

I understand that there can be a difference in flow rate.
(And I would love to find data which would allow identifying the flow
rates of various injectors and/or manufacturer's specs)

Other than differnces in flow rate, I am a loss to explain why there
are so many different injectors, why sometimes the same injector may be
used on engines of different capacity and why similar or nearly
identical engines may use different injectors.

What characteristics does an injector have other than flow rate
and duration of opening (controlled by the computer)?




TIA
DR

Ads
  #2  
Old August 20th 05, 05:49 PM
« Paul »
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Default

Dirtroadie wrote:
>
> I have been searching but have not been able to find information
> relating to the difference in electrically operated fuel injectors.
>
> I understand that there can be a difference in flow rate.
> (And I would love to find data which would allow identifying the flow
> rates of various injectors and/or manufacturer's specs)
>
> Other than differnces in flow rate, I am a loss to explain why there
> are so many different injectors, why sometimes the same injector may be
> used on engines of different capacity and why similar or nearly
> identical engines may use different injectors.
>
> What characteristics does an injector have other than flow rate
> and duration of opening (controlled by the computer)?


Easy: Cost.
Email or call an injector maker and ask.
  #3  
Old August 21st 05, 01:55 PM
B Squareman
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Posts: n/a
Default


"Dirtroadie" > wrote in message oups.com...
> I have been searching but have not been able to find information
> relating to the difference in electrically operated fuel injectors.
>
> I understand that there can be a difference in flow rate.
> (And I would love to find data which would allow identifying the flow
> rates of various injectors and/or manufacturer's specs)
>
> Other than differnces in flow rate, I am a loss to explain why there
> are so many different injectors, why sometimes the same injector may be
> used on engines of different capacity and why similar or nearly
> identical engines may use different injectors.
>
> What characteristics does an injector have other than flow rate
> and duration of opening (controlled by the computer)?


Some injectors will spray in a direct string, others will spray in a cone
shape. Some require high pressure (VW TDI for example) some low.






  #4  
Old August 21st 05, 02:30 PM
pater
external usenet poster
 
Posts: n/a
Default

Volume

  #5  
Old August 21st 05, 03:34 PM
KjunRaven
external usenet poster
 
Posts: n/a
Default

"Dirtroadie" > wrote in news:1124551438.304651.130440
@z14g2000cwz.googlegroups.com:

> I have been searching but have not been able to find information
> relating to the difference in electrically operated fuel injectors.
>
> I understand that there can be a difference in flow rate.
> (And I would love to find data which would allow identifying the flow
> rates of various injectors and/or manufacturer's specs)
>
> Other than differnces in flow rate, I am a loss to explain why there
> are so many different injectors, why sometimes the same injector may be
> used on engines of different capacity and why similar or nearly
> identical engines may use different injectors.
>
> What characteristics does an injector have other than flow rate
> and duration of opening (controlled by the computer)?
>
>
>
>
> TIA
> DR
>


flow volume, coil voltage, spray pattern and mounting differences is the
only thing i can see as unique for applications. it would be nice if they
were all the same but i have wanted that (generic except for length) on
something as simple as wiper blades for years. it will NEVER happen.
'unique' keeps prices up..........kjun
  #6  
Old August 21st 05, 04:38 PM
Dirtroadie
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Posts: n/a
Default


B Squareman wrote:
> "Dirtroadie" > wrote in message oups.com...
> > What characteristics does an injector have other than flow rate
> > and duration of opening (controlled by the computer)?

>
> Some injectors will spray in a direct string, others will spray in a cone
> shape. Some require high pressure (VW TDI for example) some low.


Well, yes, feed pressure would be another variable, since most
injectors for gas engines are little more than valves that open and
close and feed a spray of lightly pressurized fuel (~40 psi)into a low
pressure area (the intake manifold.

Diesel injectors, of course, operate differently since they must force
fuel into a cylinder somewhere close to the point of maxiumum
compression (~250-400 psi for typical diesels). So diesel injectors
need not be a part of this discussion.

I guess ultimately what I am wondering about is how well a typical ECU
(computer) can compensate for a change in injectors. In theory it would
seem that such compensation would be very straightforward as long as
the injecctor had (1)a sufficient flow capacity for the top end and
(2) did not require too short a pulse at the low end.

DR

  #7  
Old August 21st 05, 05:00 PM
Don Stauffer
external usenet poster
 
Posts: n/a
Default

Dirtroadie wrote:
> I have been searching but have not been able to find information
> relating to the difference in electrically operated fuel injectors.
>
> I understand that there can be a difference in flow rate.
> (And I would love to find data which would allow identifying the flow
> rates of various injectors and/or manufacturer's specs)
>
> Other than differnces in flow rate, I am a loss to explain why there
> are so many different injectors, why sometimes the same injector may be
> used on engines of different capacity and why similar or nearly
> identical engines may use different injectors.
>
> What characteristics does an injector have other than flow rate
> and duration of opening (controlled by the computer)?
>
> TIA
> DR
>


Electronic fuel injection is what made fuel injection possible for the
mass market. The last carburetors were actually electronically
controlled also.

The problem has always been how to measure the exact amount of fuel to
add to gasoline, which must be added to the WEIGHT of air entering the
induction system. While there were a number of ways to measure the
VOLUME of air entering a system, WEIGHT is much harder.

Carburetors in the fifties through seventies were marvels, actually
containing fluidic computers to try to convert volume flow into weight
(mass) flow, and they did a reasonable job, but not perfect by any
means. To obtain full benefits of FI, one had to do a better job.
Except in racing engines, which could be run very rich, this was very
hard to do. The first electronic fuel injection systems actually had an
analog computer as part of the system- very expensive.

When digital electronics became widely available at reasonable prices,
it solved this problem reasonably well. Remaining carbs went
electronically (digital) controlled, EFI went digital, and the rest is
history. As EFI was becoming a consumer product, different methods of
mass flow rate, oxygen sensors, cheaper temp sensors, etc. were
developed too. Modern EFI does an amazingly good job at controlling
mixture, with of course, feedback from oxygen sensors. So it is a
closed loop, servo controlled system.

Room for improvement? Sure. Weak link is oxygen sensor. The so-called
transfer function curve from existing ones is funny shaped, and not
conducive to good servo control. People are working hard on that
problem, or at least were when I retired, and I assume they are continuing.
 




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