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2013-14 Shelby GT500
The Resurrection of "The ACCUSER"
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<blockquote data-quote="4VandHemiKiller" data-source="post: 17045670" data-attributes="member: 49914"><p>Interesting</p><p></p><p>1. It depends on the specific compressor and also if said compressor suffers from any inlet restriction (as rear feed/side entrance PD superchargers normally do). </p><p>I haven't seen much in the way of KB 4.9 air flow data. </p><p></p><p>How many CFM are you expecting from a 4.9L supercharger with a 4" upper/10% OD lower @ 7500 rpm? What inlet/throttle body setup do you expect to see that CFM with? </p><p></p><p>2. If all variables remain totally equal then a decrease in supercharger output CFM will result in less boost and and increase in output CFM will result in a more boost. </p><p></p><p>3. Airflow restriction</p><p></p><p>4. From what I'm reading he's asking you to support the rationale that the ~200 HP gain observed by Van was solely from a reduction in parasitic loss from moving to a larger supercharger. </p><p>I too find this conclusion dubious without a full dyno graph and a full boost curve to confirm it.</p><p></p><p>Yes both dyno pulls saw a peak boost reading of 25 psi <em>but</em> were they both making 25 psi @ 7000 rpm (or whatever RPM peak HP occurred)? </p><p></p><p>My suspicion (without knowing all of the details) is the smaller supercharger most likely suffered from a inlet restriction of some sort and <em>most likely</em> experienced a boost drop through the dyno pull.</p></blockquote><p></p>
[QUOTE="4VandHemiKiller, post: 17045670, member: 49914"] Interesting 1. It depends on the specific compressor and also if said compressor suffers from any inlet restriction (as rear feed/side entrance PD superchargers normally do). I haven't seen much in the way of KB 4.9 air flow data. How many CFM are you expecting from a 4.9L supercharger with a 4" upper/10% OD lower @ 7500 rpm? What inlet/throttle body setup do you expect to see that CFM with? 2. If all variables remain totally equal then a decrease in supercharger output CFM will result in less boost and and increase in output CFM will result in a more boost. 3. Airflow restriction 4. From what I'm reading he's asking you to support the rationale that the ~200 HP gain observed by Van was solely from a reduction in parasitic loss from moving to a larger supercharger. I too find this conclusion dubious without a full dyno graph and a full boost curve to confirm it. Yes both dyno pulls saw a peak boost reading of 25 psi [I]but[/I] were they both making 25 psi @ 7000 rpm (or whatever RPM peak HP occurred)? My suspicion (without knowing all of the details) is the smaller supercharger most likely suffered from a inlet restriction of some sort and [I]most likely[/I] experienced a boost drop through the dyno pull. [/QUOTE]
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2013-14 Shelby GT500
The Resurrection of "The ACCUSER"
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