Griff injectors - Wide angle or pencil beam spray pattern?

[dnb]

And why...

My deal for some silly big injectors fell through for several reasons Not too worried as it gives me a bit more time to think about things, and saves me rushing in due to finding a bargain!

What would you go for - wide angle (say about 20 degrees) cone spray or pencil beam? Location of injectors will be more-or-less as standard. The injectors will be sized such that for the majority of the time, they will only be fired when the intake valve is open. (sequential is easier than most people think - and when it comes more-or-less for free it would be rude not to!)

My current thoughts are that the wide angle would be nice if the heads were designed for it. As everything is at the moment, the spray will just hit the port walls and a reasonable amount will drop out of suspension and form puddles of liquid fuel. Whereas the pencil beam will hit the open intake valve, cool it down and vapourise the fuel nicely.

I know this is an immensely complex subject and involves air flow speed into the cylinders and so on... This is pretty much going to be the same in both cases, so it can be a secondary consideration.

Any thoughts?

[GreenV8S]

dnb said:

(sequential is easier than most people think - and when it comes more-or-less for free it would be rude not to!)

Have I mentioned that I hate you?

I would go with your theory about puddling. I don't know how far the spray extends, but pictures of them being tested suggest that the visible plume extends for 2-3 inches. If a narrow plume can extend this far down the inlet tract while remaining largely clear of the walls then that would seem to be the ideal answer to minimise wall wetting. On the other hand if the petrol is definitely going to hit a wall then perhaps the wider the plume the better if it increases the amount that gets carried downstream by the air. The real answer is probably something completely different ...

[griffter]

My theory (based on no practical experience whatsoever) would be that you want the fuel suspended in the air mix as best possible. This requires it to be finely atomised so that the incoming air charge sweeps the fuel mist into the combustion chamber. Thus I'd have thought the greatest atomisation (ie finest spray - smallest droplet size) would be to the greatest advantage. SO I'd go for a wide angle assuming this atomises best.