Hi,

I'd like to set up a twin turbo on my inline-6 engine. After studied the twin turbo system, I see an unusual turbo setup. While the intake of the conventional parallel system is designed to feed air to the turbo individually, the one I found on a diagram is one turbo is fed by the other. However, the exhaust sides are alike, yet, it won't called a compound or 2-stage turbo set up. Could anyone please tell me the advantages and disadvantages of this setup?

Also have a look in the performance section of this list.

The parallel turbine / parallel compressor was used on the aftermarket M103 / M104 inline 6. This was supposed to give less boost lag. It is also used on some V engines as it makes for better packaging.

The parallel turbine / series compressor would be for higher boost pressure, just like a 2 stage shop air compressor. However, I see an imbalance in exhaust pressures between cyl 1-3 and 4-6 that would lead air flow and mixture issues between the two banks.

Typically, the turbines are in series for good balance. It is possible to have series / series with 4 turbos as each bank of the engine is treated as a separate engine.

with turbobandits setup,you can get 600hp without engine,and trans mods.they claim one turbo is better,less lag.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Modern ball bearing turbos made twin turbo setup obsolete on inline 6cyl engines. Just look at what the aftermarket is doing with the 2JZ for example.

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The 2JZ factory configuration is a spin on the parallel setup above. It runs on a single turbo to start then the second turbo chimes in -



I don’t know if it’s the same turbo twice or each is optimized for its role.

Sixto
98 E320s sedan and wagon
02 C320 wagon

Taking the compressor side first. It depends what problem you need to solve. Two compressors in series give increased pressure. Two compressors in parallel give you greater volume. But this applies to free air effects, ie, without an intake manifold. plumbing or intercooler. If your intake path has significant impedance, the parallel setup won't come close to doubling flow, but the series blowers just might.

With a series configuration, the turbo impellers might benefit from being asymmetric, because the second turbo will operate under greater load. This is because the first compressor creates higher pressures (and thus greater density) at the impeller of the second. So the second compressor consumes more power to further compress an equivalent volume of gas. Asymmetric compressors should also help turbo lag: the lower powered compressor would likely spool faster. You could probably get further benefit from an intercooler between the stages.

With parallel operation, I think the turbos have to be symmetric, otherwise the slower compressor will bleed flow from the faster compressor.

On the impeller side, there's no advantage, and considerable disadvantage, to series operation. The first impeller would simply reduce the energy available to the second. So regardless of how the compressor side is arranged, the impeller side will always be parallel.

And the aftermarket replaced that mess with a single modern ball bearing turbo because it flows more air while providing better throttle response. Or look at BMW's evolution from the N54 to the N55. Twin turbos on an inline engine are obsolete.

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