[Healeys] 100M cold air boxes and flow

[Oudesluys]

You forget that SU's are pressure compensated so there should not be no 
issue with "ram air pressure", which is rather low anyway (unless you 
use a mighty big cone) and not to be compared with the pressures of 
turbos or compressors.
If you want more mixture in your engine get double DellOrtos, Webers, 
Mikunis, Solex's, any decent sidedrafts on a proper manifold, one barrel 
per cilinder.
Kees Oudesluijs.
Op 19-1-2012 12:56, Chris Dimmock schreef:
> Hi Alan,
> No, you cant pressurise a cold air box.
> Never set up your cold air box so it rams air in at higher than
> atmospheric pressure straight into your carbs
> If you do, the end result will be too much air, not enough fuel, a
> lean mixture and a destroyed/ melted piston or 4. Probably at high rpm.
> A cold air box is just that. A cold air box  - the ability for cold
> air to be sucked into a carb on a hot engine. A cold air box generally
> is not sealed. It is open at one end (or somewhere) so it can't
> pressurize and force air into the carbs at higher than atmosperic
> pressure.
> Think about an old supercharger for a minute. The carb - often an SU
> on the sort of superchargers found on BMC cars - is on the outside, it  '
> mixes the fuel and air which is then compressed and fed to the engine.
> I.e it is a fuel air mix which is compressed, not compressed air alone.
> I've seen the results from some homemade "cold air sealed ram boxes" -
> and trust me, unless your dad owns a piston company, you don't want to
> go there.
> So the end issue is the 'flow' into the cold air box is pretty
> irrelevent, it's just a way to get cooler than underbonnet air in
> front of the carbs.
> Whether the volumetric area of a 100m cold air box is enough - no idea.
> But pressurize or seal a cold air box on SUs at your own peril....
>
> Best
> Chris
>
> Sent from my iPhone
>
> On 19/01/2012, at 5:55 PM, Alan Seigrist<healey.nut at gmail.com>  wrote:
>
>> Adam -
>>
>> Any flow.....
>>
>>
>> It's about the air pressure, not the air temperature.  Basically it's
>> a cheap supercharger when you are driving fast.
>>
>> Alan
>>
>> On 1/14/12, Adam Nolde<adamnolde at yahoo.com>  wrote:
>>> All,
>>>
>>> ...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.
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