A&Q about 350Z
Q:
According to VAG on my TDI engine these are the stats:
1.4 TDI
Configuration
Diesel 1422 cc (86 in³) inline three cylinder
Head
2 valves, overhead camshaft, 18 to 19.5 compression ratio
Aspiration
variable turbine geometry tubocharger, intercooler, 2.3 bar absolute boost
Fuel
Pump direct injection,(PD Pump injector, Pumpe-Düse) Bosch EDC 15 engine management
Output
55 kW (75 hp) @ 4000 rpm, 195 N·m (144 ft·lbf) @ 2200 rpm
However my car DOES not boost anywhere near 2.3 Bar of boost. Does that spec mean the Turbo can run at 2.3bar or that it should run at 2.3 bar?
Plus my car has been mapped which i presumed the boost would have been turned up (given thats the majority of the power increase) but i'm only getting 16-17 psi on my boost gauge.
A:
"Absolute boost is the measure of pressure above or below mean (normal) atmospheric pressure whereas relative boost denotes the difference in pressure caused by supercharging. Note that this definition refers to absolute boost not absolute pressure. When a normally aspirated engine is running vast amounts of air is being drawn in. As the throttle assembly forms a barrier to this airflow (even when wide open) there is always a low pressure region (partial vacuum) down stream from the throttle body. Lets say that this part of the inlet manifold has a pressure of 1.5 psi below atmospheric at full throttle. If a supercharger is fitted and supplies 4 psi of boost then its relative boost is 4 psi whereas its absolute boost is 2.5 psi above atmospheric pressure (4 psi minus 1.5 psi lost in the throttle body). Real world fluid dynamics are a lot more complex than this but the model is a good approximation of what actually happens. Conventionally engineers only measure absolute boost whereas product marketeers prefer the more flattering relative boost. It is relative boost however that relates to real performance gains most closely particularly when dealing with small capacity superchargers."
Ok?
A:
According to VAG on my TDI engine these are the stats:
1.4 TDI
Configuration
Diesel 1422 cc (86 in³) inline three cylinder
Head
2 valves, overhead camshaft, 18 to 19.5 compression ratio
Aspiration
variable turbine geometry tubocharger, intercooler, 2.3 bar absolute boost
Fuel
Pump direct injection,(PD Pump injector, Pumpe-Düse) Bosch EDC 15 engine management
Output
55 kW (75 hp) @ 4000 rpm, 195 N·m (144 ft·lbf) @ 2200 rpm
However my car DOES not boost anywhere near 2.3 Bar of boost. Does that spec mean the Turbo can run at 2.3bar or that it should run at 2.3 bar?
Plus my car has been mapped which i presumed the boost would have been turned up (given thats the majority of the power increase) but i'm only getting 16-17 psi on my boost gauge.
1 Bar = 14.7psi
Atomospheric pressure (psia) is approx. 14.7psi or 100kpa at sea level.
Absolute pressure referred to here is psia + psig = 1 bar + 1.3 Bar (gauge )= 2.3bar or 33.81 psi.
Gauge pressure is 33.81-14.7psia (assuming sea level)= 19.11psig
Dont know why you car is "only showing" 16-17 psi and the boost has been up though.