I've been crawling all over the web trying to figure out how to pick a turbo, and I've learned just about everything there is to learn about turbos except how to actually select one. That part I can't get my mind around, and none of the turbo shops are answering my emails. So, time to turn to the mass brain.

I need two turbo recommendations, if you folks would be so kind. One would be for a 10.5:1 compression 6.2L, the other would be for a 9.5:1 7.0L. I would prefer a twin scroll or twin volute single turbo recommendation. Engine redline will be 6000RPM to 6200RPM. I specifically want a twin scroll/volute turbo, because my research indicates that you can combine both banks into a single exhaust line feeding both volutes, then put a valve that closes off one volute. This causes the turbo to come in 2000RPM sooner than a single scroll/volute turbo of the same size will, then as RPM builds the valve can be opened to open both volutes to support exhaust flow at the upper RPM.

The other thing about this, the turbo will be rear mounted on my project. No option for underhood mounting on this project.

Looks like this is the turbo I'll need according to Garrett.

https://www.garrettmotion.com/racing-and-performance/performance-catalog/turbo/g-series-g42-1200/

Further research into the valving thing looks like what I might want to do is doable. A blow off valve can handle closing off half of the turbo, and will flow enough to handle half of up to a 3 inch single line exhaust. I'd just need to work out a way to keep this particular blow off valve OPEN at all times, except under WOT conditions. Someone already did it.

https://www.theturboforums.com/threads/faster-spool-and-more-boost.296574/page-18

However, it's all getting very expensive and complicated at this point. I'll probably dig on this a little longer, but I can also get a forged Gen 4 427 built out of a Dart block that will make my HP target NA for quite a bit less than a turbo engine is looking to be, and would only require that I burn 91 octane. The turbo would have more upside potential, but I dunno, 780HP in a Dakota might be a little overboard here already.

NA is not as fun as the boosted life! Why not go with the 427 with dish pistons and later on change the cam and go boosted after you get tired of it and save more money for the turbo setup

I suppose I could. The shop I'm talking to says that the same engine built to 9.5:1 would produce around 550HP at the crank, and would be boost ready.

NA tuning is going to be a lot less complicated than boost tuning. Wall wetting, positive pressure maps, etc are just more things to deal with versus the standard NA. And it looks like NA is less expensive to maintain and requires less "baby-sitting" than all the additional turbo equipment will.

Nevertheless, I am looking forward to hearing about this build!

I also recommend 427, I also use them.