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Message: <blockquote data-quote="tooslow" data-source="post: 236095" data-attributes="member: 9239">DYNO NUMBERS!!!!! can't wait to see the results. i hope you guys are making respectable numbers.i follow both ford and chevy tech info. fan of both. so, i'm going to share a bit of info on rotrex blowers from the other side.there are a few people using the C38-81 unit in kits for LT/LS engines, so maybe we can learn some stuff from those who are using them.W2W, a GM tuner, sells a rotrex C38-81 unit as well as KB units, vortech units, and porcharger units. their c38-81 kit costs $3,000 and is their cheapest kit. it includes the head unit and mounting brackets. no plumbing. One of their shop tunned cars, a GTO with a 392ci LS2, made 520rwhp with a maxed out c38-81. It made just over 650flywhp. Kevin at W2W states that the c38-81 makes out just around 650flywhp at 8psi on LS/LT engines. on the larger cubed engines, they feel the c38-81 is just too small of a unit. the c38-81 flows a max of 952cfm at 90,000rpm impeller speeds. the vortech s-trim and procharger p-1sc flow considerably more cfm at max impeller speeds.But, here is the huge BUT, they say that the blowers are the most effecient they have and are more than worth the money for them.why? because they don't have the typical linear boost curve of other centri units. they build low end boost much quicker than other centri units and tend to have better torque curves as a result.comparing a twin vs the rotrex vs other centri's you have this.the twin builds boost instatly, but has poor high rpm flow.the typical centri builds boost slowly but has lots of high rpm flow potential.the rotrex DOES NOT build boost as fast as a twin, it DOES NOT have the high rpm flow potential of a typical centri, BUT it DOES build boost faster than a typical centri and DOES have more high rpm flow potential than a twin screw.it is a good middle of the road blower. nothing more, nothing less.is this $3,500 kit worth it? IMO, depending on dyno results to come... worth every damn cent.If, you are looking for reliable, cheap, effective middle of the road performance. i wouldn't argue against this blower.i have no doupt that at 6-10psi (a 281ci mod will see more boost from this blower than the bigger LS/LT engines do) that the c38-81 rotrex will outperform a s-trim/p-1sc. it will have comparable peak numbers, with a better curve.IMO if you are looking for 10+psi and 450-500rwhp, a vortech or procharger is also worth ever cent of their $5,000 price tags.</blockquote>