Sequential Turbos: 1 small and 1 big?
 

I have been thinking lately (uh oh!) and was wondering...

Can you keep the low-rpm turbo stock and just replace the high-rpm turbo with a bigger one?

Sorta like having a big sequential turbo for big HP, but also having the low-rpm turbo for responsiveness and quick takeoffs.

I'm sure the sequential vacuume solenoids and what-not present a problem, but this would be a good problem to tackle.

It's pretty damn complicated. You can't simply just bolt a turbo on there, you have to use the stock turbine housing, and that's where limits start to come in. If it was easy, BNR wouldn't have kept themselves up late for many nights figuring out their turbo upgrades :).

Our stock turbine shafts are thin and can't take the weight of a bigger compressor, the Y-pipe has to be able to bolt on, the oil/water feeds are shared....it gets REAL complicated.

In theory, yes, that would be keen, but a practical application is extremely complicated, especially when cost for something like that is involved.

Dale

It's allot easier to just make a custom twin turbo setup without the use of the stockers, I've been in the process of making a twin turbo setup, its takes allot of time and MONEY but it can be done, some have already done it. But back on subject the stock twins wont take the abuse.

It is definitely possible, but it would require a lot of complicated control and tuning to make it work right.

The biggest challenge is how to transition the work split from the smaller turbo to the larger turbo smoothly. If you just randomly pick a small turbo with a large turbo, when the smaller turbo chokes out and it is time to transition, there will likely not be enough exhaust flow to spool the larger turbo up, resulting in a large boost drop off during transition. Prespool will help, but the whole setup needs to be very well matched, tuned and controlled.

Kevin