[Healeys] 100M cold air boxes and flow

Josef.Eckert at t-systems.com Josef.Eckert at t-systems.com
Thu Jan 19 06:52:03 MST 2012


As far as I know, the overflow pipes of the carbs should go into the cold air
box and are sealed at the air box to preasurize the fuel reservoirs, by the
ram effect occurs. This gives a richer flow of fuel.

Josef Eckert
Konigswinter/Germany

-----Urspr|ngliche Nachricht-----
Von: healeys-bounces at autox.team.net [mailto:healeys-bounces at autox.team.net] Im
Auftrag von Bob Spidell
Gesendet: Donnerstag, 19. Januar 2012 14:09
An: Adam Nolde
Cc: healeys at autox.team.net
Betreff: Re: [Healeys] 100M cold air boxes and flow

I recall reading a magazine article--probably one of the club mags--about a
guy that raced a 100M.  He got better performance with a couple velocity
stacks on the carbs.  Dunno if he proved it with a dyno or track times, but he
was
convinced.    Also, the box is mildly pressurized by the air under the valve
cover that vents into the box (at least
ours is).

OTOH, the box looks pretty cool.

Bob




On 1/13/2012 8:56 AM, Adam Nolde wrote:
> All,
>
> Has anyone conducted or read the results of anyone else's research
> regarding the fluid dynamics of the 100M cold air box?
>
> I'm no engineer, but a
> keen mind looking at the 1956 cold air box design can quickly work out
> the fact that it may have some ill effects on air delivery at higher
> RPM's.  I'm specifically concerned about the size and depth of the box
> causing delivery issues for both, but more likely the rear carb.
>
>
> I've done some very crude
> calculations and crude bench testing just as a base to understand the
> flow involved and the possible scale.  I've learned my engine can suck
> as much as 263CFM at 100% VE, but obviously it should be less, so I use this
as a max.
> That puts the velocity at each carb above 85mph static, but much
> faster during intake stroke.  The velocity at the air box inlet is
> above 65mph static.  The box depth in front of each carb opening is
> only 1.75".  I can see potential for not only vacuum creation and
> inefficient atmospheric replacement, but add to that the inefficient
dynamics of the flat and non radiused orifices.
> I've also discovered a fair amount of scavenging occurs between carb
> orifices in-spite of the wide and presumably ample open ended box.
>
> Anyway, I've
> theorized that the probable advantage of thermodynamic control
> supplied by the air box, may be negated by its inefficient design and
> inability to supply sufficient volume.
>
> If anyone has done or knows of some CFD (computational flow dymanic)
> modeling and, better yet, 3d image modeling.  Please let me know where
> to access the information.
>
> Thank you and kind regards,
>
> adam nolde
> 203-606-4675
>
>
>


--
*******************************************************************
Bob Spidell           San Jose, CA            bspidell at comcast.net


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