diesel_guy86 wrote:
Spool up is more of a function of the turbine wheel, the less work it has to do, the faster it will spin. A compressor wheel that is larger, more aggressive, and moves more air, will require more work from the turbine. So spool should be expected to be slower.
Look up the spool time of a Garrett gt2560 turbo, vs a gt2554. Exact same turbine and housing, different compressors, different spool up times.
the bigger wheel will indeed move more air at the same rpms, or in another way will move the same amount of air as the factory turbo at a lower rpm, therefore being more efficient.
all your going to gain is cooler boost. This engine is very flow restrictive and will not take more flow without upping the pressure. I think this wheel will give a slight bump up to 18-20lbs and after that I don't think there will be much difference.
Georgi, I believe vnt turbos operate in "stages" and not in real time with the boost. When boost hits a certain goal, the vanes move to the next stage and so on. So really the turbo is free to do what it wants untill it hits that goal. There's no time limit on when it gets there.
Wouldnt the turbine be able to operate in a more "open" position with the billet wheel allowing less restrictive exhaust flow?
I do know that the people with 7.3 PSD say they are great. In fact some of of the reviews I saw say they feel like they lose a little top end but the rest of the power band is better.