I was looking over the logs from late last year on the stock engine compared to logs with the built engine which has head work and cams and thought that this would make for an interesting forum post.
This first graph shows a pull on the stock engine, stock turbo with an upgraded IWG. The interesting point to me is that at a much lower wastegate duty cycle (35.3%) the turbo has no trouble hitting it's target of 1.7bar or 24.7 psi of boost. This snapshot was taken at 6390 RPM.
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Now compare this to a pull made today on the built engine with cams and headwork. Same turbo. Same IWG. Same RPM when the snapshot is taken. Compared to December, we can see how much harder the closed loop boost control is driving the wastegate solenoid in an attempt to hit the same 1.7bar boost target. The base duty is right is set to 49.7%, yet we see that the WgFinalDuty1 (the duty cycle actually being applied to the solenoid) is ramped up to 66% by the PID and yet we're still not able to make more than about 22psi. The issue gets worse as RPM climbs and the engine wants more air. In fact about 4600 RPM the stock turbo has trouble hitting the boost targets and maxes out around 22 psi.
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I found this interesting because while we all conceptually know that doing head work and cams can make an engine more efficient, it's kinda cool to actually visualize how the engine is essentially calling the turbo a "sissy" because it can't keep up.
Bottom line, a turbo upgrade is totally worth it; dare I say necessary.
This first graph shows a pull on the stock engine, stock turbo with an upgraded IWG. The interesting point to me is that at a much lower wastegate duty cycle (35.3%) the turbo has no trouble hitting it's target of 1.7bar or 24.7 psi of boost. This snapshot was taken at 6390 RPM.
Now compare this to a pull made today on the built engine with cams and headwork. Same turbo. Same IWG. Same RPM when the snapshot is taken. Compared to December, we can see how much harder the closed loop boost control is driving the wastegate solenoid in an attempt to hit the same 1.7bar boost target. The base duty is right is set to 49.7%, yet we see that the WgFinalDuty1 (the duty cycle actually being applied to the solenoid) is ramped up to 66% by the PID and yet we're still not able to make more than about 22psi. The issue gets worse as RPM climbs and the engine wants more air. In fact about 4600 RPM the stock turbo has trouble hitting the boost targets and maxes out around 22 psi.
I found this interesting because while we all conceptually know that doing head work and cams can make an engine more efficient, it's kinda cool to actually visualize how the engine is essentially calling the turbo a "sissy" because it can't keep up.
Bottom line, a turbo upgrade is totally worth it; dare I say necessary.
