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optimum injector spray pattern

Posted: Fri Nov 14, 2008 6:17 am
by jk35
I came across a link to a video of various injectors being 'squirted by a testing apparatus. This attempt to demonstrate the differences between types of spray patterns quickly convinced me of the fact that fuel injectors are NOT generic parts, but leaves me with yet another unanswered question: How do you determine the CORRECT (or best) injector for a particular engine?

I'm interested to know how much effect the spray pattern could have regarding x-tau settings? A very wide angle would obviously cause much more wall wetting than a tight/narrow one, right? -But there must be reasons for the various angles, and the fundamentals of this is what I can't seem to find much on. any enlightenment would be greatly appreciated.

Re: optimum injector spray pattern

Posted: Fri Nov 14, 2008 12:07 pm
by jk35
I hadn't thought of it that way. Thanks for the enlightenment!

As for choosing the "best" injector for a _________ (engine) {in my case, an Audi 058a AEB 1.8l turbo} How do you make that determination? I suppose I could jury-rig a fuel pump/rail/injector apparatus, -like what I saw on the video on USRT's website (I don't know if I'm allowed to post links, so I'll refrain from such until I have certainty) "Usually Sideways Racing Team" or 'USRT' has a couple pages of fueling products, most of which have in depth descriptions as well as some videos demonstrating various products, principles and information. The one I'm referring to once again, simply focuses on the differences in spray pattern, and goes on to impress that "injectors are NOT generic items".

SO, I could part together an apparatus, err... -contraption is probably a better word to describe what I'm thinking about piecing together! This would enable me to test spray a stock injector, test spray the new injectors and compare results. Of course the problem here is that I'm not yet able to improve upon VAG's original equipment as this would only allow me to match up to whatever the German Engineers decided was best suited for their goals (which I'm sure has NOTHING to do with the fueling of a 125hp per cylinder DD! ) This is only marginally better than messaging or calling a parts dealer and asking their (biased) opinion :?

Lance, what you just explained is quite valuable, but of course this adds to my growing list of variables and unknowns. I've been digging through SAE docs, but haven't yet found anything I could apply to this subject. I'm guessing that it would take a flow bench to actually measure results, but I'm also guessing that I'd be reinventing the wheel even if I could use one to analyze optimum spray pattern/injector type
(far beyond my capabilities anyway)

:idea: Perhaps someone can provide some "rules of thumb" on injector selection :?: