472/491

wwentzler said:

The reason it works on sled pull setup as a single, has to do more with the fact it spools quicker on our relatively small displacement engines. Diesel fuel is more efficient at making power at lower rpm, so quicker spool typically leads to more power.

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How is this relevant when the engine is dynoed on a loaded negative sweep? Your assumption does not hold water in the real world, especially if you have spent much time around an engine dyno.

The big difference between the 74/83mm and 82/87mm in regards to flow is not the wheel size itself, or the turbine AR, it's the difference in the diffuser.

The same way a single turbo applies to an atmospheric charger in compounds. Negative sweeping takes care of transient lag, yes, but as you drag the engine down, there is still shaft speed changes from turbine to turbine.

My original point wasnt that an s500 is what he should use, it's that a 96x88 turbine is too small for a 91 compressor.

Sorry for muddying up thread.

bigkev12valve said:

So do you think I will be hurting myself with the 83/1.0 housing? Just wondering cuz I found a decent deal from a buddy with a 72/83/.90 is the main reason why I ask about it. But if I'm actually going to be hurting myself then I might as well get the 87.1.0

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I run an s467.7/83 with 1.10 as a secondary and drive pressure is threw the roof.