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A richer mixture is required to avoid detonation at these boost pressures. Note that Abbott does not require that you modify the intake system and use a low restriction exhaust. So it needs to be designed to cope with the heat of high boost in an otherwise stock vehicle. The mixture is probably appropriate for these unknowns. It is not a custom fuel map for your system.
The HP is determined by the mass flow rate of air, and given that all of the oxygen is reacted, I doubt that HP is reduced because of the mixture.
Given that the BPC valve is a bleeder valve, a stiffer wastegate is needed to reduce the early opening and lag characteristics of the bleeder valve. Yes, they could have increased boost solely via the ECU, but the lag would still be there. So perhaps the new actuator and its setting is the better solution. The ECU does have the fuel cut moved to around 22 PSI. You could fit a ball-spring MBC and get some interesting results as well. But the first two gears might be undriveable.
Contemplate the fact that even if the ECU was used to solely increase the pressure, that at 1.2 bar of boost, the exhaust back pressure from the turbine will be over 2.4 bar. These pressures acting on the wastegate valve face will also tend to force the valve to open prematurely and thus also tend to increase boost lag of the control system. Another reason why a change to the wastegate actuator is desireable.
Note that intercoolers do not work very well on a wheel dyno as the air flow through the intercooler is nil. The charge air will be hot. The ECU may respond with even richer mixtures. So the developed air flow mass rate will be less than on the open road.
As the higher air and fuel rate that you are developing with your Abbott gear, the wastegate exhaust flow will be creating even more of a flow choke as the flow re enters the main flow just at the turbine exit. This creates a back pressure that limits power. This effect is more severe as boost pressures are increased. The back pressure directly eliminates shaft HP and the volumetric efficiency is reduced by the high pressure exhaust left in the cylinders which reduces induction of AF mixture. Note that with conventional turbochargers with integral wastegates, that the exhaust manifold pressures are around 2X's the boost pressure. So at 1.2 bar of boost, you have around 2.4 bar of exhaust manifold back pressure. As you increase the CFM's of a conventional turbocharger, the wastegate flow choking effect is getting more and more significant, so at higher boost pressures, the ratio of exhaust back pressure to boost pressure will be getting worse. This is also compounded by the fact that you will be running over the compressor map's area of highest efficiency and into the lower efficiencies. This also will increase the ratio of exhaust back pressure to boost pressure, and increase temperatures and reduce charge air density... more so on a dyno with no air flow to get the IC working properly.
See the posting by Brad from a couple of weeks ago where they modified the stock turbo charger and vented the wastegate bypass exhaust flow to atmosphere instead of leaving it to choke the turbine discharge flow. The dyno results were very impressive. For a street vehicle, the wastegate flows must be reintroduced to the main flow upstream of the cat converter. This does require some custom work to reintroduce the flow smoothly.
A dyno run is good to compare to another dyno run. Not good for much else. Dyno run data will provide for a comparision to other states of modification. Turbo dyno runs are very unrealistic compared to on road performance. Normally asperated engines do not have such limitation of the validity of dyno data.
If you have the target boost pressure and are not running lean, then that is all that there is. You can try to reduce intake and exhaust pressure drops and lower temperature.
If you had an all ECU solution and compared it to an ECU plus actuator solution. At the same pressures you would see roughly equal dyno results. But on the street, the ECU+wastegate solution would be much more responsive and faster.
I assume that you gave the Abbott IC. What model/year do you have?
posted by 208.24.17...
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