Very simple, allows me to switch back and forth from my MBC to ECU control while I drive. I love the low-end torque of the MBC but it gives me tractions problems and lower gas mileage. Instead of trying to explain it all I made this diagram.
(All black lines are pressure hoses and the colored line is the electrical power)
Parts Needed:
12V solenoid
A few cm/inches of hose
2 tee fittings
Some electrical wire and a switch
The differences between the MBC and the ECU are very apparent. The MBC has much better torque up to ~3400 rpm but above that the ECU gets pissy and retards timing, the power feels very flat from then on to redline. When the ECU is in control low-end torque is about 40 ft-lbs lower (proven by dynos) and max boost is only 18 psi. The top end however feels much stronger and continues to push me into the back of the seat. It is interesting to note that above 4000 rpm the T25 turbo can only manage 16 psi, so even through the MBC and ECU are supply the same boost pressure the power outputs are very different.
The next question is obvious, how to work the switch to get the best of both worlds. It would be a hassle to try and switch it every time I ran it up the rpm band. Maybe if the switch was mounted on the top of the stick shift, but I really don’t want to start cutting that up. Maybe an electrical switch tied into the rpm signal?
Eric

(All black lines are pressure hoses and the colored line is the electrical power)
Parts Needed:
12V solenoid
A few cm/inches of hose
2 tee fittings
Some electrical wire and a switch
The differences between the MBC and the ECU are very apparent. The MBC has much better torque up to ~3400 rpm but above that the ECU gets pissy and retards timing, the power feels very flat from then on to redline. When the ECU is in control low-end torque is about 40 ft-lbs lower (proven by dynos) and max boost is only 18 psi. The top end however feels much stronger and continues to push me into the back of the seat. It is interesting to note that above 4000 rpm the T25 turbo can only manage 16 psi, so even through the MBC and ECU are supply the same boost pressure the power outputs are very different.
The next question is obvious, how to work the switch to get the best of both worlds. It would be a hassle to try and switch it every time I ran it up the rpm band. Maybe if the switch was mounted on the top of the stick shift, but I really don’t want to start cutting that up. Maybe an electrical switch tied into the rpm signal?
Eric