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Re: EFI 'd Carb Manifold...

To: Richard Fox <v4gr@rcn.com>
Subject: Re: EFI 'd Carb Manifold...
From: Dave Dahlgren <ddahlgren@snet.net>
Date: Thu, 10 May 2001 12:57:04 -0400
I would mount the nozzels back by the plenum to get as much atomization before
it got to the port. It may slightly affect the throttle response( slow it down)
but the trade for better mixing with the air i think is worth the chance. Worst
case weld in 2 sets of bosses and move them closer if need be at the track.
Dave

Richard Fox wrote:
> 
> OK what if you were making a manifold for a flat head 4 cylinder with
> Siamese ports? I was thinking of mounting the throttle body about 10 inches
> from the valves with a plenum behind it and 4 #6 Hilborn nozzles. 2 tubes of
> 1 1/2 ID (port size) to the manifold face. I was trying to atomize the fuel
> and hope each valve would get its fair share. I also have a #2 nozzle near
> each port face attached to an electric pump to help with starting only.
> Rich Fox
> -----Original Message-----
> From: Dave Dahlgren <ddahlgren@snet.net>
> Subject: Re: EFI 'd Carb Manifold...
> 
> >In my opinion it is like this, the factory deal is set up for emissions and
> very
> >good performance at very low flow rates typical of all the tests they have
> to
> >pass. most cars use less than 30 hp most of the time so the amount of air
> and
> >fuel is very small and velocity in the runner is pretty low, so they try
> for the
> >best possible shot to get the fuel in the port with very little air flow to
> >help. they also need the injector close to the port to help with closed
> loop
> >operation, keeping things close to the cylinder helps close the loop, same
> goes
> >for the O2 sensor. this is contrary to performance use. Generally you want
> the
> >injector as far away as you can get it for more time to atomize the fuel.
> the
> >carb converted manifolds are a compromise to be honest and the ones made
> for a
> >single 4brl are the worst. See my page for what a 302 ford intake ought to
> look
> >like converted to a race piece. the one listed as a turbo 302 intake is the
> one
> >to look at, it will support about 1200 hp.
> >Dave Dahlgren

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