good article on batch vs seq

[norbs]

i found this article explaining that actually batch fire is better than you thought!!

SDEFI article




Whats your opinion?

 

[Craig Smith]

There are certainly idle quality and driveability advantages to sequential injection, especially with larger injectors. Batch fire systems fire the injector twice per combustion cycle, so on a system with very large injectors and a very short idle pulsewidth, the amount of time that the injector takes to start spraying fuel once the signal is applied will approach the time that it's supposed to be spraying fuel in the first place. This presents injector control issues, and it's difficult at best to maintain a desirable air/fuel ratio under these conditions. Switching to sequential injection frequently solves this problem because it only fires once per combustion cycle, so the error induced by the injector opening time is substantially reduced. As an example, you will get much better fuel control with a single 2.5 mS injector pulse than you will get with two 1.25 mS pulses. Once the total pulsewidth becomes long enough as engine speed and/or load increases, this problem diminishes.

I don't follow their explanation on why you need bigger injectors with sequential vs. batch-fired injection. No matter how you fire the injectors, you still have the same amount of time available to fire the injector. Injector duty cycle is defined as a ratio of the amount of time the injector is on to the amount of time between combustion events on a given cylinder. I'm not sure how they define a true, timed sequential system, but they seem to imply that you can't have a 100% injector duty cycle with a sequential system. I don't understand why that would be the case.

It's a cheap system for people who aren't very picky about how their car runs.

 

[9SECVSIX]

Thanks Craig

9sec.

 

[norbs]

i will have to re-read what they are talking about, some of it doesn't make that much sense, you are correct