Not sure if a discussion on turbos has occurred but

[wanda]

I was thinking about the old diesel engine and how noisy and lack of power, e.t.c, it was.

Now turbo diesels (and petrols) are almost automatically the norm. I was thinking what would be the best way to get rid of the initial delay before the turbo boost kicks in. Twin turbo is a good idea, i.e a mix of small and large turbos. Small one to take you to the big one.

Now BMW 550d with 3 turbos has perplexed me a bit.

https://www.youtube.com/watch?v=cqERH9fky2Q

https://www.youtube.com/watch?v=isSjS...layer_embedded

In theory they have a small turbo to boost from idle then the small one takes over then finally the big one takes over.

Assuming we reach the point where the big turbo kicks in, the other turbos can not spin or "create" the air flow that the big one can so can we assume it would automatically switch off?

I was thinking of experimenting on a 1.5 dci engine with a twin turbo system. (When money is saved).

Kingston University took the 1.5 k9k engine and reported some power gains but thought it would be more than reported.

https://www.ricardo.com/Documents/Downlo ... harger.pdf