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<blockquote data-quote="na svt" data-source="post: 5619952" data-attributes="member: 35346"><p>No, the intake is not the bottleneck. The stock intake keeps peak power rpm at about 6200 and a short runner (1.5" removed) raises that to about 6500-6600rpm, but even then the power drops off substantially the further you go up in rpm. Stock springs are reliable to 7k and at roughly 7200 they float. Your stock cams, like any stock cams can rev to 7500rpm, but their duration keeps the peak power at a much lower rpm. You can move the chagne the overlap to slow the drop-off after peak power is made but there are penalties when doing so like loss of power down low. You will want peak power to occur at 7000-7200rpm or so if you want to shift at 7500. </p><p> </p><p>In a purpose built motor like those that race NMRA factory stock, the 96-98 cams are used and they shift at roughly 7500rpm. However, the heads are much better, the intake provides much higher velocities and the compression is a lot higher. There is a lot to overcome when working with B heads and the B head intake...especially when using stock cams. </p><p></p><p>Below is a dyno chart from a stock cammed, B headed, short runner intaked motor. If the rpm is carried out to 7500rpm the power will be about 75rwhp lower than peak.</p><p><a href="http://imageshack.us" target="_blank"><img src="http://img504.imageshack.us/img504/5681/jimssvtwx3.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p></p><p>Why do you want to turn 7500 with stock cams?</p></blockquote><p></p>
[QUOTE="na svt, post: 5619952, member: 35346"] No, the intake is not the bottleneck. The stock intake keeps peak power rpm at about 6200 and a short runner (1.5" removed) raises that to about 6500-6600rpm, but even then the power drops off substantially the further you go up in rpm. Stock springs are reliable to 7k and at roughly 7200 they float. Your stock cams, like any stock cams can rev to 7500rpm, but their duration keeps the peak power at a much lower rpm. You can move the chagne the overlap to slow the drop-off after peak power is made but there are penalties when doing so like loss of power down low. You will want peak power to occur at 7000-7200rpm or so if you want to shift at 7500. In a purpose built motor like those that race NMRA factory stock, the 96-98 cams are used and they shift at roughly 7500rpm. However, the heads are much better, the intake provides much higher velocities and the compression is a lot higher. There is a lot to overcome when working with B heads and the B head intake...especially when using stock cams. Below is a dyno chart from a stock cammed, B headed, short runner intaked motor. If the rpm is carried out to 7500rpm the power will be about 75rwhp lower than peak. [URL=http://imageshack.us][IMG]http://img504.imageshack.us/img504/5681/jimssvtwx3.jpg[/IMG][/URL] Why do you want to turn 7500 with stock cams? [/QUOTE]
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