Quote:
Originally Posted by ahausheer
I have mixed feelings about the TVG. On the one hand better power/torque curves are always welcome but on the other it adds complexity and is one more variable that car enthusiasts have to deal with, which is a turn off. We want a greater ability to modify the car ourselves and this ability is slowly eroding. If the TVG system makes it harder to tune or realize Hp gains it may end up being a negative for the car and the brand. This car is already loved not only because it handles well but because its a simple design that appeals to car enthusiasts in a similar way as the Honda B or K engine. Perhaps a more elegant and simple solution could be found that does not include valves in the intake plenum. If the TVG system doesn't get in the way of aftermarket support or possibilities thereof then I am all for it. Either way, I watch with excitement to see how this engine will evolve.
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Same can be said about DI itself being anti-enthusiast in nature. TVG may not have been the best solution for WRX owners. But it really makes me question about it in this application.
TVG is mainly used in the past as a primary purpose to restrict air flow, during idle resulting in reduced emissions. But with DI in place and a weak stratified charge injection at idle, the idle emissions and fuel consumption has already made signficant improvements. Making TVG redundant...
TVG was really counter-productive in WRX with already horrible manifold AITs from the factory being turbo and experiencing noticeable heat soak. Does the FA20 also suffer from the same AITs with its phleonic resin compound intake manifold and not experiencing hot intake charges?
Why couldnt subaru use variable intake lengths if they were really targeting smoother TQ charcteristics via intake accoustic tuning? Rather than go TVG..
FA20DIT....wheres the dip? look at that graph...is that the same FA20 with just a turbo? This is really impressive on a non-STI turbo subaru engine and with a incredibly low emissions table compared to the EJ.
With DI in place, we really ultimately require less air to make power per stroke, vs the ratio of air+port fuel where we pretty much guess based on tailpipe AFRs.