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Old 04-20-2022, 09:52 PM   #401 (permalink)
14Q60awdSPORT
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Quote:
Originally Posted by DrBacon View Post
You may be better off with a fixed boost/pulley size anyways honestly. What you gain in low end torque from hitting peak boost earlier in the powerband you lose by decreased efficiency beyond that. This isn't a turbo where you are just bleeding off the excess wasted combustion anyways, you are making the engine work harder by spinning the supercharger at a certain rpm producing a specific CFM, by bleeding off the excess you are essentially wasting "work", also position of the wastegate/bypass valve matters as well, hopefully it's pre-intercooler.
Yes that has always been my thought process, it does make 10lbs of boost by about 4k rpm whereas a 10psi pulley would only be making about 5.5psi at same rpm. So you’d end with same peak power but the current pulley setup will make way more power across the entire powerband.

Typically a general rule is 1psi add 6.7% more power but takes about 1.7% power away to create that psi with a supercharger. Generating 20+psi but only using 10psi isn’t very efficient but the supercharger spinning lets say 50k rpm with zero back pressure or in this case 10psi, is a lot easier than doing it against 20+ psi of back pressure so it’s not quite as inefficient as it initially seems, but still could be better optimized.

I always thought a 16psi pulley would be a good middle ground in still being able to hit about 10-11psi by 5500rpm and then flatline it only bleeding about 5psi at redline vs 13psi or so now.


I am already tuned so if I do retune it might be because of a built block and then I’ll be making max boost anyways. But who even knows timeline on if/when ecutek is following suit to COBB.
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