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From: david mccandless <daval@iprimus.com.au>
Subject: Re: [FlyRotary] Re: Fuel Injector Position (was  Re: Makingprogress on Chris n Dave's Velocity Engine)
Date: Tue, 21 Jun 2005 09:55:47 +0800
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>


  It is the latent heat of vaporization of fuel that causes the rapid 
cooling. In a carb, the venturi is where the fuel starts to vaporize,  
usually just prior to the butterfly,so the ice forms on the next 
available protrusion, ie the butterfly.  In EFI, if the injector is 
upstream, where the vaporization starts, then the TB is likely to ice 
up. This is only my opinion on a possible problem, with this config. 
Road cars usually have the primary injectors (those most susceptible to 
icing, because of partial throttle) downstream of the TB, just prior 
entry to the combustion chamber. This is for reasons other than icing, 
but it has the effect of avoiding icing.
   Dave McC
On 21/06/2005, at 9:18 AM, Jim Sower wrote:

> But wouldn't that be true of ANY injectors placed a significant 
> distance from the block?  I think carb ice is pretty much always 
> associated with fuel sprayed into a venturi, and the injectors in our 
> application are always downstream of the "venturi" formed by the 
> partially open throttle.
> I wouldn't worry ... Jim S
>