This thread talks about cold air and "Ram" effect. The cold air improvement
is measurable. Although I don't have any data, thermodynamic analysis can
calculate the HP improvement for a reduction in inlet temperature. Much of
the improvement is due to increased density of cooler air. The "Ram" effect
is more elusive on slow vehicles. Moony Aircraft used to come with a pilot
operated ram air intake. When the aircraft gained altitude the pilot was able
to open an inlet in the nose of the airplane to induce air directly into the
engine and bypass the filter. My recollection was that the increase in power
was sufficient to increase the speed of the airplane 2-3 mph. This was a
1-1.5% increase in speed. Since dynamic (ram) pressure and drag are both
proportional the velocity squared, the same percentage increase should be
realized at normal automotive speeds. As you can see this isn't going to
cause any neck snapping difference to our cars. In fact you might gain more
by taping over all of the body panel gaps.
Craig Wright
Simon Favre wrote:
> To look at some good examples of successful race cars that used them
> back then, look under the hood of an Alfa GTA or better yet, a TZ.
> The earlier Giulietta Spider Veloces had cold air induction, but the
> path was more convoluted than on a GTA or TZ. The Spider had filtration
> but the GTA and TZ did not, AFAIK.
>
> My Bourgeault Formula Junior has one. The box tapers in toward the rear
> and each carb throat has a brass velo stack on it inside the box. The
> intake originally came from a tube that went thru the cockpit to the
> wheel well in front. This only had a screen for filtration, and also
> made the process of pulling the cockpit section a pain. I took out the
> tube and fitted a K&N inside the cockpit. The air intake is still cold,
> but it doesn't get any ram effect. The seal between the airbox and the
> float chamber was not ideal, so I think I'm better off. Most of the
> later Formula Juniors just had velo stacks sticking out the side of the
> car. I've been meaning to try building a cylindrical box around a K&N
> and fitting a tube back up to the wheel well to try the ram effect
> again. The access to the carb bodies is unrestricted. Access to the
> venturis, velo stacks, etc. is through a cover plate bolted onto the
> air box. Captive nuts in the box and button head screws thru the plate
> hold it on. The whole thing is quite a work of art, typical of
> Bourgeault.
>
> "Jack W. Drews" wrote:
> >
> > Everything I read and am told by "experts" says that supplying cold air
> > to carburetors results in more horsepower. I notice, however, that
> > almost no one uses one. I'm thinking of building one that will also
> > allow ease of opening for the frequent attention those sice-draft carbs
> > seem to need.
> >
> > In a never-ceasing interest in engineering my way to the back of the
> > pack,
> >
> > 1) anybody else use one?
> >
> > 2) what design flaws should I avoid?
> >
|