supercharger electronics (basic)

[mark kibort <mkibort@xxxxxxxxxxxxxx>]

Message text written by INTERNET:bmw@domain.elided
><I think Bret hit it on the head when he said  " the Bosch alternator in=

an
E30 to drain over 5 hp from the engine when it is under high load. =

Therefore,
chances are good that the electric supercharger could actually cost
power.">>

??????>>>>>>>>>>>>>>>  No, as stated below by some very intellegent
statements,  altenators produce 90 amps max, so at 14 volts that is 1.5 h=
p
with all of the inefficiencies of the copperlosses and others, call it 2 =
hp
tops!!!!!!!!!!

and if it draws or costs 2 hp and Ive gained 8 hp for a 4.7 liter or 4 hp=

for a 1.6 liter, it is a net gain .  Youre forgeting the power of the air=

fuel mixture burn .



A couple of things to remember:
1) 1 HP =3D 746 watts
2) amps x volts =3D watts
3) 65 amp alternator charging at 14.2 volts =3D 923 watt output
>>>>>>>>>>>>>>>>>YES  , youre right here, but remember this for later =


Alternators and not nearly efficient so if we factor copper, iron, and
machanical  losses into the equation and say 1 hp x 746 =3D  746 watts  =3D=

52.53
amps at 14.2 charging volts out of an alternator that's taking 5 engine h=
p.

>>>>>>>>>>>>I worked many years with brush and brushless motors.    the
altenator is inefficient by maybe 70 % , so how does producing 1000 watts=

of electrical energy take 4000 watts of mechanical energy to make it  .  =

this is flawed !!!!

Ok so far,  now, what will this get us?  I think a 1hp electric air
compressor
*might* be able to deal with .4 psi at 270 cfm (I'm using 270cfm [cubic
feet
per minute] as an example for a 182hp engine - think E-28)  =


>>>>>>>>the fan produces over 500 cfm free air and .35 or so at 270 cfm =

for the E28 , your right!!!! =


This is what I *think* we might get:

182 hp (stock) naturally asperated - 14.7 psi (one atmosphere)
therefore: 182 hp / 14.7 psi =3D 12.38 (we'll use this as a factor)
14.7psi + .4 psi (electric supercharger *boost*) =3D 15.1 psi
15.1 psi x 12.38 (our factor) =3D186.93 HP

>>>>>>>>>>>Nice thinking , a little rough but nice thinking,    problem i=
s
that im getting 242 on the dyno without the fan and turn it on and it goe=
s
to 251 .     on the 4 banger, 88 to 92.   so , the only thing youre missi=
ng
is that the altinator does not produce the drag youre predicting.


Best case =3D .7 hp loss.    >>>>>>>>no, 4 to9 hp gain.  net!!!!!
Now from this we should determine the effect the electric compressor has
on:

1) weight - plus 50lbs?        NO, ONLY 1 LB FOR THE FAN , WHERE DID YOU
GET 50
2) intake air turbulance       NO, AIR IS STRAIGHTEN AFTER THE FIRST BEND=
,
IVE SEEN IT INBENCH TESTS AND BESIDES THAT, THE AIR FILTER DOES ALOT OF T=
HE
STRAIGHTENING.
3) reliability?        10 YEARS OF MUCH HARDER DUTIE CYCLES   2TO 4 MIN O=
N
TIMES AT MUCH HIGHER HEAT.  =

APLICATION WILL ONLY BE 10 SECOND ON MAX.   ALREADY TESTING FOR SEVERAL
MONTHS ON THE TRACK.  NO PROBLEMS.

This is what I think - I'd be interesting in counter points but please
don't
tell me about dyno charts - heck,  I've got an SI board that'll tell you =
my
engine is running at 3,000 when it's at idle.

??>>>>>WHAT IS A SI BOARD.   DYNO IS EVERYTHING.  (as long is the operato=
r
knows what he isdoing)  anyway, I back all dyno runs with 10 speed runs a=
t
60-100 mph  .  You would be surprised, very good coorelation here.

Christopher
>>>>>>>>>>>Mark
ERAM system

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