Re: shrouded in air

[dlawson@ball.com (Dave Lawson)]

Steve,
>WRT air shrouded injectors:
>I'm pretty sure that the o-rings ensure that the air gets to mix with the
>fuel better.  It is my understanding that this is the main benefit of the
>shrouded injectors in the first place, i.e. better mixing of the fuel with
>air.

I checked with the Probst book and there is one paragraph about these
injectors. Like you said, the air is channeled around the injector and
then directed around the tip of the injector to help atomize the fuel.
The cross section of the setup shown in Probst is a bit different than
the 89 injector I have.

>If you are not using the 200's injectors you might want to think about
>blocking the air passage that feeds the shrouds as well.  At least think
>about trying it either way ... it may not hurt anything allowing the 
"shroud"
>air in, but since you don't have the proper injectors you may get a
>different airflow pattern, which might affect the way the engine runs.

I haven't yet found the air inlet which supplies air to the shroud region.
The brass(?) injector mount fixtures in the 89 head appear to be identicle
to the ones in the 83 head. Maybe I am missing something. And when I
had the intake manifold off there was nothing obvious around the inlet
port. Probst shows air supplied by the inlet manifold in his example, but
there is no such beast on the Audi manifold. I agree that by using the 83
injectors, air could be flowing freely around the injector tips which could
result in a non-optimum air flow pattern.  But at this point I am getting 
ansy
to hear this thing run. It will be a close call which will breath air first, 
the
franken-q or the new child which is due in <2 weeks.

>It wasn't clear in your post whether or not you tried mounting the '89 FD
>on the '83 airbox.  If you did and it didn't work, what was the problem?
>I guess I could pop a couple of hoods this evening and find out for myself
>(at least '83 urQ against '88 5kTQW).

I bagged the 89 FD swap for now. Since I went with the 83 fuel lines which
were still connected to the 83 FD, it was an easy choice. The plan is to get 
it
running using the 83 setup. Once this step is complete, to then think about
fitting the 89 parts. I might have to fab a custom set of injector lines
to fit the 89 injectors. That or source a set of MB engine ur-q injector 
lines from
the UK. I will look into it more in the coming months. Other ideas gladly
accepted.

 -
Dave Lawson  dlawson@ball.com
Boulder, CO