Like that yer how

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Notice the pipe gets smaller after the head. At work we get a lot of race boats in there for pipe work on turbos,have seen one with 3 turbos mounted inline it was a bit#h to work on.A few with twins turbos and supercharged.

Notice in the illustration, & remember it IS just an illustration, that the second turbo is the larger one of the two.
Wouldn't the flow to it be restricted by the smaller, first turbo. This would surely hobble it. The same problem would occur if it was the other way around, except that at full power, the small turbo would back up the gasses.
Either way, the maximum flow through the larger one would be dictated by the maximum volume that the smaller one would pass. Yes?

More, the longer the exhaust plumbing, the more the gasses will cool,... & contract, reducing the volume to the larger turbo. Short plumbing & heavy insulation will address this problem somewhat, but it needs to be kept in mind.

YEP the shorter the pipe the better.The little one will come on at the lower end of rev range then run out.2nd turbo takes over for the rest of rev range so on and so on.TWO the same size will work OK.3 inline were all the same size with sea water going through as intercooling after each turbo.

A bit off point but closely related, why run twin side draughts and have the fuel pulsing in, why not run one big carb and have a constant flow?
and to note, I agree with L18, the rules of logic apply.

on the point of twin turbos, I feel both turbos should be evenly fed by ALL cylinders, through a pre turbo header type arrangement. will it work hell I don't know but its another idea

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How can the larger one take over if the volume of gas available to it is restricted by the smaller one, keeping in mind that the internal passages in it ARE smaller?

Remember, i am discussing the design that we can see in the illustration.

Air from the the first turbo is compressed then cooled to make it dense/thick then compressed again and cooled.If not cooled temp will go out of sight after 2nd turbo.First turbo is bigger in illustration so not much nobbiling there,so there is say 15lb pressure there over the rev range.Then the 2nd starts you get a boot ferther up the range.My book says air is thinner than water,Vacume is stronger that pressure ,AIR WILL PASS THROUGH THE FIRST ONE .

Well I think L18_B110 and the phunk docta spok are both right to a degree. What do you think of this concept.

Exhaust gas has mass. When the gas exits the cylinder it is under pressure of up to 50 - 80 psi. Pressure causes the gas to flow to an area of lower pressure (atmosphere).

Velocity of gas flow is determined by the pressure of the gas and the resistance of the path it travels to atmosphere.

As the exhaust valve shuts, it stops further flow of gas. The existing gas on the low pressure side of the valve continues to travel towards atmosphere as a discrete gas packet.

The gas packet has measureable mass and velocity (energy).

For a given cylinder volume of discharged gas the smaller the packet volume, the greater the gas velocity will be (at that point in time) as it travels to atmosphere.

This means there is more energy available for release in the packet when it is smaller.

As this packet comes in contact with a turbine wheel, energy is disappated by rotating the turbine wheel as the packet expands against the flat face of the turbine wheel.

The pressure differential across the turbine wheel blades determines how much energy is available for transfer to the wheel.


In the working system, packets of gas are released from the cylinder at a rate proportional to engine speed.

When gas packets are being generated at a rate where gas cannot bypass the turbine wheel without overcoming the static friction of the turbine assembly, the wheel will begin to rotate.

At low engine speeds the packets give distinct pulses of energy to the turbine wheel as it passes to atmosphere.

As engine speeds increase, production of gas packets increase proportionally, buillding up density before the turbine until the turbine increases speed.

As gas packets build up in the manifold, the gas flow becomes more homogenous like a single mass.

In split pulse turbos the packets were divide into two streams to minimise frictive losses to the turbine wheel.

Thank you Feral

Quote:
But rules of logic dont apply to my theory?

Cheers Steve