User Tools

Site Tools


injdata-lowpwvariance

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
injdata-lowpwvariance [2011/12/15 05:57]
twdorris
injdata-lowpwvariance [2012/03/13 12:40]
twdorris
Line 1: Line 1:
 ====== Injector Data - Low PW Variance ====== ====== Injector Data - Low PW Variance ======
 Fuel flow rate through an injector is affected by a number of different things. ​ This page focuses on the fact that even with nicely matched sets down to 2ms (0.002 seconds) pulsewidths,​ there can still be significant differences in your typical operating range. Fuel flow rate through an injector is affected by a number of different things. ​ This page focuses on the fact that even with nicely matched sets down to 2ms (0.002 seconds) pulsewidths,​ there can still be significant differences in your typical operating range.
 +
  
  
Line 8: Line 9:
  
 ===== Overview ===== ===== Overview =====
-Most injector testing places will not typically test below 4ms or if they do, certainly not below 2ms.  For the most part, that's usually fine.  Testing from 4ms up to 16ms (with a total time of 20ms, for example) provides a pretty good idea of the general behavior of the injector. ​ As the chart below illustrates,​ injectors are almost always very linear in this area.+Most injector testing places will not typically test below 4ms or if they do, certainly not below 2ms.  For the most part, that's usually fine.  Testing from 4ms up to 16ms (with a "​typical" ​total time of 20ms) provides a pretty good idea of the general behavior of the injector. ​ As the chart below illustrates,​ injectors are almost always very linear in this area.
  
 |{{linear-vs-nonlinear-areas.png?​300|}}| |{{linear-vs-nonlinear-areas.png?​300|}}|
Line 16: Line 17:
  
 For example, on a set of 1450 cc/min injectors running on gasoline with a 2.0L 4-cylinder engine, you'd expect to idle in the 1.6-1.7 ms range. ​ And as you can see in the next section, the behavior of any given injector down in that range can be very different from the behavior in the 2ms range. ​ It doesn'​t sound like much of a difference, but it can be as much as a 30-50% difference in some areas. ​ That's huge!  That's like having one cylinder running at 14.7:1 and another running at 9:1 with the __same__ pulsewidth. For example, on a set of 1450 cc/min injectors running on gasoline with a 2.0L 4-cylinder engine, you'd expect to idle in the 1.6-1.7 ms range. ​ And as you can see in the next section, the behavior of any given injector down in that range can be very different from the behavior in the 2ms range. ​ It doesn'​t sound like much of a difference, but it can be as much as a 30-50% difference in some areas. ​ That's huge!  That's like having one cylinder running at 14.7:1 and another running at 9:1 with the __same__ pulsewidth.
 +
  
  
Line 31: Line 33:
 ^  // Click to enlarge //  ^ ^  // Click to enlarge //  ^
  
-To be clear, this behavior isn't specific to the FIC BM1450s. ​ Every injector set out there can have this problem to varying degrees. ​ We're forcing these injectors to operate in an area where they were really not intended to produce precise flow.  Basically, we're using the injectors in an application where they weren'​t ​designed ​to be used.  So we have to pay a little extra attention to the details.+To be clear, this behavior isn't specific to the FIC BM1450s. ​ Every injector set out there can have this problem to varying degrees. ​ We're forcing these injectors to operate in an area where they were really not intended to produce precise flow.  Basically, we're using these injectors in applications ​they were not designed ​for.  So we have to pay a little extra attention to the details.
  
injdata-lowpwvariance.txt ยท Last modified: 2012/03/13 12:40 by twdorris