Twin Turbo kit?

[Dimman]

Originally Posted by sw20kosh

I disagree. There is no magic in a twin turbo set up. Physics is physics.

Ex. 6 cylinder engine:

3 exhaust ports (50% of total) spinning each of the two turbos

vs.

6 exhaust ports (100%) spinning one turbo

Inertia of two turbines/compressor wheels = inertia of one larger turbine/compressor wheel. (assuming same target flow levels)

To reverse your logic, a properly sized single turbo will spool faster than two turbos.

I am welcome to math or physics that can prove two turbo's has an inertial advantage over one turbo. If we go with your logic, then why aren't there 6 tiny turbos on 6 cylinder engines?

It is because if one of those 6 tiny turbos flows X, a single large turbo will flow 6X. Each one of those 6 tiny turbos needs Y energy to fully spool at 3k rpms (total of 6Y energy) and the single large turbo will need 6Y energy to fully spool at 3k rpms. So all you gain with 6 tiny turbos is more complexity.

This is why manufacturers played with twin turbo's in a sequential manner. The design allowed 100% (instead of 50%) of the exhaust energy to go to one small turbo. This made spooling quick. When the rpms (thus the exhaust energy) were sufficiently high enough the exhaust flow was split with 50% of it going to each turbo. (this is if the turbo's were the same size)

I am not sure but I think there was a second design where the exhaust flow was completely switched from a small turbo over to a bigger turbo depending on rpms and engine load.

Look into the inertia issue a bit deeper. You're assuming same mass plus same placement of mass.

[usptwins]

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