Boost
From Celica GT-Four / Alltrac - ST165 ST185 and ST205
Available Unit IDs: C01, C02, C03, C04, C05, C06, C07, S01, S02, V01, V02, V03.
Example: <google uid="C01"></google>, <google uid="C01" position="left" ></google>
Boost is positive pressure in the intake manifold. This is what the turbo provides and allows the engine to produce far higher power per litre than a naturally aspirated version.
Standard Boost Levels
- ST165 - 0.7 bar (10 psi) max in 3rd,4th and 5th, 0.5bar in 1st and second.
- ST185 - 0.75 bar (11psi) max in 3rd, 4th and 5th, 0.55ish in 1st and second.
- ST205 - 0.9 bar (13 psi) max in 2nd+, boost control seems more complex on the 205.
Standard Boost Control
On all models the boost level is controlled by the TVSV which is essentially a bleed valve. When high pressure is allowed by the ECU the TVSV opens and bleeds some of the pressure off the actuator. This means the actuator remains shut until a higher pressure. The ST205 may have better than ON-OFF control of the TVSV, this isnt confirmed as yet.
If you disable the TVSV you will be locked into LOW boost and need to install another boost control device to increase it.
Max Boost on Standard Engines
Any boost increase will reduce engine lifespan, period. You're adding stresses to the engine that it wasnt given in the first place. That said small and careful increases can achieve good gains at limited risk. Documented "safe" max values are:
- ST165 - 12 psi.
- ST185 - 12 psi. (Fuel cut is set at 12psi on most ECUs)
- ST205 - 16psi.
More can be achieved but the problem with the 185 and 165 is they have a paper head gasket and higher boost tends to blow this among other problems I'll document later when i get chance. allowing 12psi in first and second will make a noticable different to the feel of the car, even if you dont go any higher.