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Date: Fri, 05 Aug 2011 10:26:54 -0400
From: Chad Robinson <crobinson@medialantern.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Ideas for direct injection
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On 8/5/2011 10:05 AM, Ernest Christley wrote:
> 1) Direct injection.  On the 13B housings, the oil injector port looks 
> like a good place to install the injectors.  The issue is that the 
> hole to the chamber is very small.  I'm thinking I would have to drill 
> it out to get a spray into the chamber, and I can't think of any safe 
> way of doing that except to completely disassemble the engine (Ugh!).
Playing Devil's Advocate here. This option doesn't sound that great to 
me. It's aluminum so it's easy to drill... But it's also very far up on 
the housing. I think you're right - there'd be no way to guarantee that 
you'd get every scrap of debris out, and you'd be just waiting for the 
failure to come on every flight. But a teardown? You have things like 
O-rings that you'll need to discard and replace ($), it's very time 
consuming to do right (hrs) and it's not without its own risks. Nick a 
seal without realizing it, pinch an O-ring, etc.

But more important, that location is so far up on the housing that it's 
entering part of the compression cycle. Do different models have these 
at different locations? Because at first glance mine look like they're 
just above where the intake ports close off. That means you may not get 
the amount and atomization of fuel that you'd get injecting it lower, 
into the intake itself or right at the ports (as the primaries do). What 
I mean is, even if you manage to get this installed, it may not work 
very well.
> 2) Build a whole new manifold.  Does anyone have a spare 6-port 
> manifold that I can cut the flange off of?
I know it's a pain to consider this, but if you add up the total time 
involved it might be less than a teardown (and the risk of the other 
answer not working).
>
> 2) Cut up my current composite manifold up and move the injector 
> placement.  I've already made a couple of "adjustments", so this thing 
> is already getting ugly.
Are you happy with your composite manifold? I waffled on this for a long 
time before ditching the plan. I'm back to fabbing from aluminum, and 
I'm just starting to lay out the pieces for a welder. (I figure I'll 
have him fab the manifold + long runner tube assembly as one piece, fab 
the intake flange plus up+over tubes as another, then figure out the 
final cut/fit for him to do the final join.) A few years ago I sent a 
gallon of some sort of high-temp, high-strength epoxy to somebody on 
this list, I forgot who, and never heard back so I figured the idea was 
dead.

Regards,
Chad