Mark,
On Weber DCOE carbs, the float bowls vent to the front of the carbs. My
current box has holes in the backplate to allow them to vent to the airbox.
Also, you can route the air filter/intake tube so that it does not cause a
ram air effect. No dyno pulls, but I just think it has to be better than
the three carbs pulling hot air from inside the engine compartment.
Hope this helps,
Hugh Barber
Hollister, CA
'73 TR6
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net]On
Behalf Of MARK J WEATHERS
Sent: Tuesday, September 16, 2003 3:58 AM
To: fot@autox.team.net
Subject: Fw: Weber cold air induction
Amigos, Kas has pretty much dissuaded me from pursuing the weber cold air
induction box, primarily due to the issues of straightening out airflow. I
guess the pressure head developed from air before the radiator shroud can
create some feed problems given the limited space. Also an inlet-fuel bowl
pessure diff on some carbs. I was planning to make individual boxes for each
carb to avoid dealing with manifold differences, which makes the problem
worse. However, a lot of experienced racers have made boxes from fiberglass
or carbon fiber to fit all three carbs, it would be interesting to see if
anyone had before and after dyno results. Another approach seems to be
insulating the carbs from the exhaust area. One approach Michael Porter has
seen ducted air over the exhaust manifold and out the bottom to carry away
heat. My personal conclusion after getting your inputs would be to construct
a sheetmetal barrier (with dead air space per Kas below) that provides a
channel for cooler air from the front of the radiator to the carb area. I
would not try to make it completely airtight to the fenderwell or hood so
that the air had some place to bleed off. Cooler air with a large 'airbox' I
guess. A bit of a project and custom to each car I would imagine.
Mark
72 TR6
----- Original Message -----
From: "kas kastner" <kaskas@cox.net>
To: "MARK J WEATHERS" <markjwea@email.msn.com>
Sent: Saturday, September 13, 2003 5:04 PM
Subject: Re: Weber cold air induction
> Got thinking , why keep you waiting for the other shoe to drop. When doing
> this deal there is a very important portion that cannot be neglected. If
> the box (must be really big for the three carbs, is air tight except for
the
> entrance, then you must lead a relief to each of the float bowls so that
the
> float bowls see the same pressure as the carb entrance. Though the
increase
> in pressure might be minute ( and it will be) that difference can stop the
> fuel from flowing into the carb as the pressure the float bowl sees is
LESS
> than that of the carb inlet. Capice?
>
> Next, I have found that there must be a relief hole in the back of the
> housing that is at least as big as the total of one carburetor inlet. In
> this case that about 2.5" I suppose. This will stop the pressure build up
> and release you from having to feed the float bowls. This also keeps the
> air incoming from swirling in the "box" and causing an unreliable and
uneven
> feed to the carburetors. Had enough yet?
>
> In the end a nice aluminum double walled heat shield under carbs with at
> least a 3" inlet pipe ( preferable SMOOTH not flexible wire hose) Nothing
> insulates as well as a dead air space, thus you have a double wall heat
> shield about 1/4" to 1/2" gap between the segments. I say the NON-WIRE
type
> hose because as the speed of the air increases the boundary layer in the
> hose increases at a terrific rate, and soon you have just a 2" or smaller
> hose really supplying the fresh air. Smooth out the hose and you can give
> the volume required to be effective. So what this calls for is pieces
> formed of fiber glass or carbon fiber or whatever over a mold. This will
> give a smooth interior and good feed. I'm sure I not telling anything new
> but kind of just reminding you that this is not a simply operation or
maybe
> not even worthwhile.
>
> I do think that a nice clean fresh air system would be a nice thing to
sell
> and to be attractive to owners.
>
>
> ----- Original Message -----
> From: "MARK J WEATHERS" <markjwea@email.msn.com>
> To: <fot@autox.team.net>
> Sent: Saturday, September 13, 2003 3:19 PM
> Subject: Weber cold air induction
>
>
> > Amigos
> >
> > I have tried a couple of sheetmetal contraptions to get cold air to my
> triple
> > webers on my TR6 but I have been limited by clearance to the fender well
> and
> > the velocity stacks. I am considering making a vacuum formed cover for
> each
> > carb with a duct for cold air piping. Is there any interest out there
for
> > something like this? Would fit any 40DCOE. Anybody alrady have a good
> > solution?
> >
> > Does anyone know of a good source for Y's for the cold air ducting? Did
> not
> > see anything in Pegasus or Racer Parts or Summit.
> >
> > Thanks
> > Mark
> > 72 TR6
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