[DeTomaso] Theoretical question of the day

[JEFFREY COBB]

On Feb 27, 2017, at 9:05 AM, Charles McCall <charlesmccall at gmail.com> wrote:

>   Will a carburated engine make more power by simply installing a freer
>   flowing air filter with no changes to the carb?
YES more power and sometimes hurts low end power and causes off idle transition hesitation because you have lowered intake resistance and only if the rest of engine management can handle it.
Though it may sound faster.
> Or removing the filter for that matter?
Removing filter may help but removing the housing most likely will hurt flow/power.
The housing, air horn, causes better laminar flow to the venturis for better air flow which induces more fuel, hence more power. Air filters do not offer that much restriction. Most of the time the airbox and routing does. Which affects most other cars not most Pantera's since they tend to have open filter units.
>   A fuel injection computer will adjust the mixture to be able to take
>   advantage of more oxygen,
yes
> but fuel flow in the carb is limited by jet size.
Not true for majority of driving, limited by jet size and venturi flow. Fuel flow from carb to throat is jetting while float needle size and fuel pump control bowl input volume. 
> I'd expect a small increase in power to be possible
TRUE
> but the fuel flow will soon be limited by jet orifice diameter,
Correct, though only at the max air speed, foot/sec, established by the venturi and carb design if you are not using ram air and high speeds. Señor Venturi's invention in 1780 + - shows more air pulls in more fuel in this case, till use maxes the throats flow rate, ie: max cfm, and turns laminar flow to boundary layer which is stagnant air puddling which damages proper atomization.
> and it won't make much more power despite the extra air.
Correct.
>   A significant change in airflow would require rejetting the carb to
>   take advantage of the improvement, right? Or wrong?
Yes, only if same carb is used and large internal changes, exhaust or ram air is changed.
>   Thanks all!
Take care, 
Jeff Cobb
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-------------- next part --------------
   On Feb 27, 2017, at 9:05 AM, Charles McCall
   <[1]charlesmccall at gmail.com> wrote:

       Will a carburated engine make more power by simply installing a
     freer
       flowing air filter with no changes to the carb?

   YES more power and sometimes hurts low end power and causes off idle
   transition hesitation because you have lowered intake resistance and
   only if the rest of engine management can handle it.
   Though it may sound faster.

     Or removing the filter for that matter?

   Removing filter may help but removing the housing most likely will hurt
   flow/power.
   The housing, air horn, causes better laminar flow to the venturis for
   better air flow which induces more fuel, hence more power. Air filters
   do not offer that much restriction. Most of the time the airbox and
   routing does. Which affects most other cars not most Pantera's since
   they tend to have open filter units.

       A fuel injection computer will adjust the mixture to be able to
     take
       advantage of more oxygen,

   yes

     but fuel flow in the carb is limited by jet size.

   Not true for majority of driving, limited by jet size and venturi flow.
   Fuel flow from carb to throat is jetting while float needle size and
   fuel pump control bowl input volume.

     I'd expect a small increase in power to be possible

   TRUE

     but the fuel flow will soon be limited by jet orifice diameter,

   Correct, though only at the max air speed, foot/sec, established by the
   venturi and carb design if you are not using ram air and high speeds.
   SeA+-or Venturi's invention in 1780 + - shows more air pulls in more
   fuel in this case, till use maxes the throats flow rate, ie: max cfm,
   and turns laminar flow to boundary layer which is stagnant air puddling
   which damages proper atomization.

     and it won't make much more power despite the extra air.

   Correct.

     A significant change in airflow would require rejetting the carb to
     take advantage of the improvement, right? Or wrong?

   Yes, only if same carb is used and large internal changes, exhaust or
   ram air is changed.

     Thanks all!

   Take care,

   Jeff Cobb

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References

   1. mailto:charlesmccall at gmail.com
   2. mailto:DeTomaso at server.detomasolist.com
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