Fuel pressure and flow rate, high duty cycle?
Posted: Tue Nov 10, 2009 10:58 am
Planning on upgrading the turbo on my stock volvo 1.7l engine, I think the first thing I need to do is to upgrade the injectors as it looks like it's already on the limit. But to be sure I need some advise here.
I've got a 4-cyl 1.7litre 8v MPI engine, turbocharged (16,2 PSI max boost). Specs (chiptuner) say the engine should have 165 bhp output on the crank.
The fuel pressure is 51.45 PSI, injectors are rated 18.29 lb/hr at 43.5 PSI. So flowrate at 51,45 PSI would be
18.29*SQRT(51.45/43.5)= 19.9 lb/hr.
At 100% duty cylce, the BSFC would be: (19.9*4)/165= 0.48 But I don't think the duty cycle will be 100% so the BSFC will be lower. Generally they say BSFC would be higher towards 0.55 for turbocharged engines?
Is this a reasonable value for BSFC?
with BSFC of 0,55 the max HP at 100% duty cylce woul be 145 HP.
The AFR is around 12.5, and it is a pretty old design engine (1990).
From what I understand is that the fuel pressure regulator will keep the pressure difference over the injector constant, so a constant flowrate of the injector can be assumed, correct?
Any help is much appreciated.
Wout
I've got a 4-cyl 1.7litre 8v MPI engine, turbocharged (16,2 PSI max boost). Specs (chiptuner) say the engine should have 165 bhp output on the crank.
The fuel pressure is 51.45 PSI, injectors are rated 18.29 lb/hr at 43.5 PSI. So flowrate at 51,45 PSI would be
18.29*SQRT(51.45/43.5)= 19.9 lb/hr.
At 100% duty cylce, the BSFC would be: (19.9*4)/165= 0.48 But I don't think the duty cycle will be 100% so the BSFC will be lower. Generally they say BSFC would be higher towards 0.55 for turbocharged engines?
Is this a reasonable value for BSFC?
with BSFC of 0,55 the max HP at 100% duty cylce woul be 145 HP.
The AFR is around 12.5, and it is a pretty old design engine (1990).
From what I understand is that the fuel pressure regulator will keep the pressure difference over the injector constant, so a constant flowrate of the injector can be assumed, correct?
Any help is much appreciated.
Wout