FMU Tweak
#23
Boost Czar
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yeah, opposite. I'm crossing my fingers a 8:1 or 10:1 disc will allow the pressure to build faster at low boost, keeping the low/mid AFR richer, then the pressure regulator should cap the max pressure to the rail keeping the upper AFR in check. But we'll see tomorrow.
#26
Well the thing that sucks about the FMU is that its only adjustable on pressure. But you see the stock ECU tries to keep the engine lean before 4k so to combat that you have to dump fuel on it since the injector on time is short. Once the car hits 4k the Injector on time increases and then the engine gets all the fuel it needs, but then tends to run too rich up top. I was generally seeing about 12.5:1 AFR's under 4300 and then past that it would dip to about 10.5:1 AFR's.
#27
I think this idea has merit, but maybe a different approach with the BEGI unit.
Basically we want to set the rate of rise and cap the upper limit. The rate of rise is already adjustable (technically) via the needle valve. What if we drilled and tapped another hole to accept another barb for 1/4" vacuum line. A the end of the barb we have a MBC and a check valve.
That way we don't modify the incomming amount of boost. Once we hit the target set by the MBC we vent the additional boost while still maintaing constant pressure on the FMU. This works for a wastegate, I don't see why this wouldn't work here. Basically you have an adjustable relief valve on the FMU.
Pick it apart, or tell me someone already thought of it!
Jay
Basically we want to set the rate of rise and cap the upper limit. The rate of rise is already adjustable (technically) via the needle valve. What if we drilled and tapped another hole to accept another barb for 1/4" vacuum line. A the end of the barb we have a MBC and a check valve.
That way we don't modify the incomming amount of boost. Once we hit the target set by the MBC we vent the additional boost while still maintaing constant pressure on the FMU. This works for a wastegate, I don't see why this wouldn't work here. Basically you have an adjustable relief valve on the FMU.
Pick it apart, or tell me someone already thought of it!
Jay
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