And this as a supplementary to my last post:
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If I may offer a few comments regarding the use of twin scroll (TS) componentry in a largely single scroll world . . .
- I recently upgraded from a regular .63 A/R T3 with a GT35R to a PT67 BB with a .70 A/R TS T4. Despite the fact that the T4 housing makes the T3 look like a toy, the response of the TS configuration of the T4 makes an open T3 feel like mud. Despite the fact that a larger turbo is used, it gives superior transient response due to the TS.
- The biggest realization when using a TS housing is that if you chose it using open housing A/R figures as a guideline, you chose too small. I know for a fact that a 1.06 A/R TS T3 spools faster than the same turbo with a .63 A/R open T3. When using TS, don't be shy about going large, because A/R figures don't correlate between open and TS housings when it comes to spool and power characteristics.
- A TS turbine housing requires a TS manifold. Fitting an open manifold to a TS housing is like putting a square peg in a round hole.
- A four cylinder engine benefits more so from a TS setup than anything else, primarily due to the latency period between pulses and blowdown isolation.
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Hsing comparison between BEP .55AR and modded Holset HX40 14cm^2 housing
The holset hsing dwarfs the BEP hsing! Notice how much of the compressor hsing you can see in the background when comparing the two turbine hsings. The 14cm housing practically hides the comp hsing when looking at it.This hsing (14cm holset)should wrk very well on a HX35 or HX40/35 hybrid. However I'm thinking of going to a 18cm or 16 cm