Conclusions and Additions
1)The cat/muffler begins to make a difference at 4500-plus rpm, and from 5000 to 6000, makes a maximum of 10-percent difference in power. The cat and muffler robbed 46 hp in the peak power range around 6000 rpm compounded, and 39 hp in the turbo-only configuration at the peak power range around 5500.
2) At 4800 rpm and 19.7 psi of boost, exhaust backpressure into the turbine exceeds 26.46, on the way up to 35-psi peak exhaust backpressure. We couldn't measure much more pressure with the MAP sensor since it went out of range. Exhaust pressure exceeds MAP under all circumstances.
3) Naturally aspirated, the Toyota 1MZ is losing torque after 4500, and the redline is 6250. This motor desperately needs more cam for huge power.
4) The supercharger was critically important in making power in the 5800 to 6500 range on the 1MZ. Viewed as a black box, the combination of the blower and engine has greatly improved volumetric efficiency in the high end. The blower acts like a big cam for the top end.
5) The supercharger is always adding boost. It isn't true the Eaton blower isn't working once the turbo is really cooking. Whereas the supercharger never made more than 5 psi by itself, the blower component of boost is as high as 9 psi in the compound configuration. We don't know why.
6) The Majestic T-61 turbo proved itself able to make 537 rwhp, which is between 620 and 675 flywheel hp. This is exactly the predicted range of the turbo as revealed in the T-61 compressor map, which provides enough air for 640 flywheel hp at 65-percent thermal efficiency, 670 hp at 60-percent efficiency.
Even with the wastegate clamped shut, we couldn't get the turbo to make more than 29.5 psi of boost, and to do that, we had to remove the turbo intake plumbing, which then made another 40 wheel hp. The average boost from 5000 to 6500 improved from 24.7 to 27.5 psi. If you're running your turbo to the ragged edge, you need a great free-flowing intake.
7) We added a second 3-bar MAP sensor that could be used to track exhaust backpressure more effectively, turbo compressor discharge pressure upstream of the intercooler, plumbing and throttle body.
8) We still didn't have enough wastegate spring to keep the wastegate from being blown open by exhaust pressure at high-power settings. The addition of a second spring inside the Majestic wastegate increased nominal boost from 6 to 9 psi. Beyond that, all additional boost was provided by the Motec-controlled pulsewidth-modulated electronic controller feeding a percentage of boost to the Deltagate side of the wastegate actuator, helping hold the wastegate actuator closed to higher pressures.
We used the higher pressure compressor discharge as a vacuum/boost source for the boost controller, but this was never more than 3-4 psi above manifold pressure, so that was the maximum pressure that could be used in our configuration to keep the wastegate closed against exhaust pressure.
We considered disconnecting the manifold pressure reference to the normal (non-Deltagate) wastegate port, and thus greatly multiplying the effect of boost pressure to keep the wastegate closed at high exhaust pressures. However, we were running very near the top of the MAP sensor, and seemed near to falling off the edge of the world in several ways at such high boost. We couldn't make more than about 22 psi of boost just using the boost controller.
9) We saw high injector duty cycles near 600 flywheel hp in initial rich configurations. However, after tuning, and at peak torque and peak power under all circumstances, we had injector duty cycle left once we began to lean out higher power levels and add timing as the power rolled over. The only place duty got tight was in the high-power turbo dyno run 036 near redline, above 6750 rpm, above peak power and torque, when we began to run out of time for injection, and hit 100 percent duty cycle. The most duty required in the compound configuration was 88-percent required above 6500, again, as time got short.
10) Turbocharging the supercharged engine was like turbocharging a bigger engine with better top-end VE.