OP, if you want something reliable go for a smaller CID engine. Either route you go the max power #'s will most likely be the same as a turbo can only flow so much air regardless of CID, however the power delivery will vary drastically.


I thought those were short blocks?

 

I have driven two trucks one with 370 and one with 408 same 91mm on both and nearly identical set ups. Turbo was laggy on 370 but had top end from hell. On 408 it's much more responsive and spools way quicker. Forced inductions has a new bb GT80X that flows almost as much as the gt91 but $600 more.

 

why not go with gt88 instead of building this high end motor? just a thought, personally i am building a 406 and i hope the s475 will hold me over for a lil while.

 

To be honest, now that I think about the fact that you are coming from a 370 with a high boost tvs2300, I think you will be unhappy with a turbo that size, maybe even with a 408, I'd consider something smaller. You just aren't going to have that touchy, neck snapping instant throttle response of the maggie. I know, I made the change myself in my crew cab last year. I went with a tc76 on a mild 6.0, even with the smaller turbo, I have to admit, I missed the response at first, but you get over it pretty quick. I'd consider either your 370 with a nice precision 76 or BW turbo, or a 408 with something a little bigger. Ask tarinitup how his throttle response is with his truck, I have no idea, but you have a lot more weight to carry around, part throttle response is a lot more important with these heavy crew cabs then it is with a light rcsb. Just my opinion, I'd just hate to see you ditch the maggie for a turbo that's maybe a little big for your setup and be disappointed right away.

 

The GT91 is the only option I have since I have it already.

 

A 408/Gt91 would be a better combo than the 370 for the street. All out race the 370 will make the same or more power if you have a engine that can keep the heads down.

 

So just stroke the LS2 I have now or should I just sell it and start over?

 

I think you should buy your buddies 427 This turbo will really love that motor!

 

Yes I know! Hey how do you know about this turbo??

 

Just my 2 cents..

Wouldnt it benefit you to build what setup you want and tailor the turbo to the particular setup? Maybe try selling the gt91, build a 408 with a respectible turbo..

I mean Id love to have an LSX427/454 with a 91 but if your talking about drivability and cost...it may be in your best interest to keep the ls2 and build a 408