Quote:
Originally Posted by Spooler
It's called compound turbo charging and is done all the time in the diesel performance world. It has also been done on OTR heavy haul truck engines. Cat has a setup like this. There is also tripple compound turbo charging. Turbo sizing is key to keep each charger in it's map.
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no compound or series charging is when one turbo FEEDS the other turbo. They use it in the diesel world because by doing so you stack pressure ratios. so if one turbo can efficiently compress the air to 39psi absolute it feeds that charge into the second turbo that can push it up to 109psi while still in it's efficiency island. Diesels love having more compression so by doing this even if the turbos are relatively small it allows the engine to run at a much higher dynamic compression ratio.
Edit: the key in sizing doing that is just to match the pressure ratio's and efficiencies of the two turbo to get the target boost pressure, and to make sure that the intake turbo can flow enough compressed air to supply the second turbo
The VH45 is no bigger than a stroked vq so by going vk5.6 you have enough extra displacement to really make a crazy build worth it. the vh is good engine, revs higher than a vk stock but it is a little small to justify it.