Here's the answer:
Ram air is doing just what the eRAM is doing, creating a differential
pressure (ie pressure outside being greater than the inside of the engine.
) In a normally aspirated car, when the throttle is wide open, the
atmosphere is trying hard (14.7psi hard) to push air into the cylinders.
However, because of restriction and pressure drops, it never quite sees the
full 14.7 psi as the pressure , its sees a 1 or 2 psi less this is the
vacuum that the intake system causes. Race engines get close to 14.7, but
never really get there. (call it 0 boost as is mentioned below) So,
if you add a supercharger, or can harness ram air, you will raise this
ambient pressure at the entrance of the intake system and this will add all
the way down the pipe, the density , and pressure of the air.
turbos that have 14.7 psi will add to the 14.7 psi ambient pressure for a
total of 29.4psi total boost. Ram air at 180 mph may raise the inlet
pressure to 14.7 or still be a little short of it with its .4psi potential.
The eRAM with its 1psi boost will also add to the ambient pressure and
will make give the engine 14.7 psi of absolute pressure given a 1psi
pressure drop in the intake system for this example. Bottom line, is What
ever the increase of pressure you can make on the inlet, this will add to
the density of the air going to the engine. Ram produces .4psi at 180
mph, but do you have a hood scoop and a nice laminar flow path to the
intake runners? probably not. The eRAM harness electrical energy and
produces this type of pressure at stand still and helps at high speed as
well.
So, to answer the comment below, you have to think that vacuum doesn't do
anything, its differential pressure that does all the work.
PV/NRT is the short of the formula, but the meaning is that if you can
create a greater differential pressure by using ram air or eRAM or
turbo/superchargers, this will increase the differential pressure and
create more dense air or mass flow that enters the engine , that is then
monitored by the Mass flow detection and matched with more fuel and then
you get more HP.
So, below , the assumptions below are correct, however the" vacuum" should
be replaced with " increased pressure" to make more HP
Mark K.
eRACING
-----Original Message-----
From: owner-dakota-truck@buffnet4.buffnet.net
[mailto:owner-dakota-truck@buffnet4.buffnet.net]On Behalf Of Jon Steiger
Sent: Wednesday, July 14, 1999 4:25 PM
To: dakota-truck@buffnet.net
Subject: Re: DML: E-RAM and RAM air
On Wed, 14 Jul 1999, Joseph DaVolio wrote:
> I would ASSume that when the eRam is off, and you are driving, the blades
of the fan are still turning. The "rush" of air thru the tube would cause
the fan to turn. Just think of a window fan when the wind blows, the fan
blades turn. Therefore, the eRam is moving and wearing out. If you attach
a variable resitor type switch to the throtle cable, you would have variable
flow. Just a thought... Of course I am not a mechanical engineer and I am
speaking out of my first part of ASSume.
>
That sounds about right to me. Others have posted and said the drag
isn't a problem, but one thing I thought I'd mention is that a windmilling
fan will create more drag than one that is stationary. (That's the way
it works with aircraft props, anyway.) I guess it depends on the motor
they used, but if it actually is stationary (unaffected by the air flow
over it) that'd be better than if it were windmilling, from a "drag"
point of view...
-Jon-
.--- stei0302@cs.fredonia.edu ----------------------------------------.
| Jon Steiger * AOPA, DoD, EAA, MP Race Team, NMA, SPA, USUA * RP-SEL |
| '96 Dodge Dakota v8 SLT CC (14.55@94.14), '96 Kolb FireFly 447 |
`--------------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
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