SOS vs Kraftwerks
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Joined: Aug 2004
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From: Planet Earth....Welcome!
All i can say is that my car makes just about 18psi with my 3.0" pulley. SOS sent me a different crank pulley than what they send with the kits. If I drop to a 3.2" it makes 17psi and if I drop to a 3.4" it makes 16psi. At least thats what Chris told me. I havent tried the other pulleys yet so I dont know for sure.
Joined: Jul 2007
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From: Long Island, NY
Originally Posted by bagherra,Nov 14 2009, 01:49 AM
SC rpm = (crankshaft pulley size / sc pulley size) * engine rpm
For instance:
5in/3in = 1.67 -> 1.67 * 8500 = 14167 SC rpm
4in/3in = 1.33 -> 1.33 *8500 = 11305 SC rpm
It seems to me that by combining the two measurements as a ratio you can maximize boost and minimize overspin of the SC. There are a few sites that exemplify this in their kits...they give the ratios and boost levels to help people decide what to get without creating SC problems. You can calculate the ratios to verify that you're not overspinning the blower.
I'm not sure what the SoS crank pulley's size is vs stock but if you knew you could work the ratio vs. SC pulley to max psi and min overspin. Hope that helps.
For instance:
5in/3in = 1.67 -> 1.67 * 8500 = 14167 SC rpm
4in/3in = 1.33 -> 1.33 *8500 = 11305 SC rpm
It seems to me that by combining the two measurements as a ratio you can maximize boost and minimize overspin of the SC. There are a few sites that exemplify this in their kits...they give the ratios and boost levels to help people decide what to get without creating SC problems. You can calculate the ratios to verify that you're not overspinning the blower.
I'm not sure what the SoS crank pulley's size is vs stock but if you knew you could work the ratio vs. SC pulley to max psi and min overspin. Hope that helps.
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Joined: Sep 2008
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Originally Posted by s.hasan546,Nov 14 2009, 09:44 AM
but wouldnt a smaller crank pulley and the same sc pulley equal less boost not more? idk totally confused here lol
It does, but you work the ratio to get the optimum combo with minimum overspin. Do a quick google search for some of the manufacturers recommendations. I found one for Mustangs...different car and SC but the same principle applies.
Joined: Sep 2005
Posts: 1,941
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From: Baraboo, WI
Originally Posted by gravesdu_99,Nov 11 2009, 06:52 PM
Hey guys. I want to do a supercharger this fall, but I can't decide which kit to go with. I know both the pros and cons of each kit. I like the finished look of the SOS better, but it sounds like the Kraftwerks might be better. Just looking for some opinions and maybe if I'm lucky a SOS and kraftwerks dyno graph overlay. Thanks guys
https://www.s2ki.com/forums/index.php?showtopic=745479
Brian
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Joined: Jun 2007
Posts: 31,070
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Originally Posted by bagherra,Nov 13 2009, 09:49 PM
SC rpm = (crankshaft pulley size / sc pulley size) * engine rpm
For instance:
5in/3in = 1.67 -> 1.67 * 8500 = 14167 SC rpm
4in/3in = 1.33 -> 1.33 *8500 = 11305 SC rpm
It seems to me that by combining the two measurements as a ratio you can maximize boost and minimize overspin of the SC. There are a few sites that exemplify this in their kits...they give the ratios and boost levels to help people decide what to get without creating SC problems. You can calculate the ratios to verify that you're not overspinning the blower.
I'm not sure what the SoS crank pulley's size is vs stock but if you knew you could work the ratio vs. SC pulley to max psi and min overspin. Hope that helps.
For instance:
5in/3in = 1.67 -> 1.67 * 8500 = 14167 SC rpm
4in/3in = 1.33 -> 1.33 *8500 = 11305 SC rpm
It seems to me that by combining the two measurements as a ratio you can maximize boost and minimize overspin of the SC. There are a few sites that exemplify this in their kits...they give the ratios and boost levels to help people decide what to get without creating SC problems. You can calculate the ratios to verify that you're not overspinning the blower.
I'm not sure what the SoS crank pulley's size is vs stock but if you knew you could work the ratio vs. SC pulley to max psi and min overspin. Hope that helps.
Joined: May 2006
Posts: 1,598
Likes: 1
From: Selma, TX
Well you are looking at PSI spec'd from the manufacturer and you don't know what volume the container was that they measured it in. Everyone is correct in that if you change the pulley sizes it makes no difference on lowering the RPMS. Meaning if you have a certain size crank pulley and blower pulley, making the blower pulley smaller or making the crank pulley larger both will increase the blower rpms. So if the blower is maxed out at the 3.0 inch blower pulley then its maxed out. You can't get anymore PSI out of it without over spinning it. Now if the 3 inch is the smallest pulley and they offer a different crank pulley, then the blower is not maxed out at the 3 inch pulley in terms of blower speed.
