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Schrappnel Knobben Tech Report
Here is as much technical data on the modification
as I have to date. I would like to do some rolling
accelleration or horspower tests, but have the car
on blocks for brake and wheel work.
Pressure BAR Stock Voltage Modified Voltage
(psig) (Abs) (Volts) (Volts)
4.0 1.27 2.21 2.377
6.0 1.41 2.66 2.79
8.0 1.55 3.08 3.19
10.0 1.68 3.50 3.51
12.0 1.82 3.92 3.63
14.0 1.96 4.34 3.70
16.0 2.01 4.77 3.76
18.0 2.24 5.18 3.79
20.0 2.37 5.60 3.81
22.0 2.50 6.02 3.83
Electrical Circuit
+12v __o
|
|
/
\<------o P sense (old)
/ |
\ \
| / R1
| \____________o P sense (new)
| |
| ___/
| // \
| --- Z1
| |
GRND __o_______o____________o GRND
R1 = 18 Ohm 1.0 watt Resistor
Z1 = 4.3 Volt 0.5 Watt Zener
Notes, There is a rounding in the curve toward the top that
depends upon several parameters, including zener saturation
current, resistance values, and the kirchoff's law results.
I could try to get closer to the 4.3 volt cutoff by using a
4.7 volt zener and an appropriate resistor, but without know-
ledge of boost maps, this may or may not be desirable. The
computer never thinks it sees above 11 psig this way, so I am
not too far off.
Plumbing Diagram
WasteGate
___
| |===========o Upper Vent Port
| | |
======= |
| |===================o===>>> to manifold
\___/ Lower | |
| port | |
\_/ | |
| |
Pressure Reg | |
____ | |
|__| Safety | |
|| Valve | |
_||_ || | |
| |==|__|====o |
| | |
|____|==================o
I am running with the regulator, guage and saftey vale under the
wipers on the windshield. It has a nice Mad max appearance :-)
It does take some time for the wastegate to fill and vent through
the regulator, but it seems like a shorter time constant than for
the turbo, so I never seem to be waiting for the control pressure.
That's it for now. Comments as always are appreciated.
paul t-