Re: Holley ProJection vs 4BBl carb

[Darrel <darrelK@domain.elided>]

Vinnie Moscaritolo wrote:

> On 1/7/99, Men from Black Helicopters forced "Darrel" to write :
>
> > For your 304 I would recommend the 502-20 Digital System ($640 in
> > Jegs) and the 534-54 O2 Sensor kit ($100). This system is for up to 275 HP
>
> I didnt know that you needed both. OK fine..

The newer 4 barrel Digital kits come with the O2 sensor. The 2 barrel digital
system does not.

> > Holley also makes a much improved system (504-13) that you could also use
> > on a 392
> > (the one above is too small for a 392), but it costs $1130 and you would
> > also need
> > the $350 4 barrel intake. It includes a lot of other sensors and an idle air
> > control motor, bottom line is that it's more sophisticated.
>
> Ok I am confused are you saying that the 304 is too small for the 4Di kits
> they seem to start at 650 cfm or would that still work.. the 4Di seem to be
> a bit more interesting, again I am worried about using it with the
> roughness of a IH engine.

I'm saying that if you later wanted to drop in a 392 that the 2D system would be
too small. The 2D system is rated for 275hp max.

But you could use the 4D or 4Di 650 CFM kit on either the 304 or a stock 392. The
4Di 650 CFM system is rated to 300hp, fine for a stock 392.  If the 392 had
headers, higher compression, bigger camshaft, etc. then you would need the 700 CFM
Di (rated to 400hp).

You wouldn't want to put a 650 CFM carburetor on a 304 because the air velocity
would be too low. But a 650 CFM throttle body is acceptable. So yes, you can use
the 650 CFM Di system. In fact, it's a *much, much* better system the 2D system.
But you would need to buy that $350 4 barrel intake also.

BTW: The 4Di is programmed with a laptop, the 2D and 4D with knobs.

Don't get too caught up in the CFM ratings of the throttle bodies. Pay more
attention to how much fuel the injectors can flow. For example, The 4 injectors in
the 650 CFM 4D flow more fuel then the 2 injectors in the 670 CFM 2D. That's why
the 4D *650* CFM model is rated for MORE horsepower then the 2D *670* CFM model.

I'm not sure what you mean by the roughness of a IH engine.  The Projection will
work as good on an IH engine as any other. As far as reliability just mount the
ECU in the cab, and do a top-notch installation.

Darrel Kline
Colorado Springs