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Cedric · Joined: 27 Aug 2004 Posts: 2608 Location: Sweden

Holset also uses same trim defenition as garrett, I have access to hundreds of holset maps if you want med to find something

And a 931 simulation model as you already seen.

Looking at trim and diamteters is not enough, two similar sized wheels with similar trims can have vastly different flow characteristics, which you only will get by looking at maps. It all depends on how you design the wheel. A HD diesel engine have very different needs to a passcar petrol engine. Its all about trading efficency at high pressure ratios vs having a wide efficiency island, in general.

In general when you go down in trim size you rotate the map to the left, so better for high pressure ratios and lower flows. The 3257 is from a low reving diesel engine, and thus its matched for that

But could still be enough for our puny engines.

When you run a restrictor you will be limited in flow when the restrictor chokes, so to get more air into the engine you will have to increase density by applying shit loads of pressure instead, the highly tuned restrictor engines have very specific compressors with maps that are really narrow and really tall.
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1980 924 Turbo
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Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

gegge · Joined: 27 Jul 2007 Posts: 1124 Location: Sweden

People are using the HX35 with great success. Would be interesting to compare the compressor to a K27. Just to get an idea of different maps. Cédric, do you have BW256 as well?
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Carl Fredrik Torkildsen

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