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- Feb 28, 2007
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- 19,528
I went with a a 3.2" alt. pulley with the 10%, so I would think 3.5" with a 15%.
You won't need a 15% overdrive with that 2.9" pulley man. You will be overspinning that blower by quite a bit, and it probably won't hold up to that for very long. With a 10% overdrive and a 3.0" blower pulley I will be at max impeller speed at 6500rpm, and I have the same blower as you. Plus, if you are looking for 17lbs. of boost, you will get that with the combination I have on mine. The max impeller speed for our blowers is 55K. Even if you only spin your motor to 6500rpm you will be at 58K. If you go to 7000rpm you will be at almost 63K. You aren't going to need to spin it that hard to reach your goal. If you feel like you have to get a 15% overdrive, I wouldn't go any bigger on your blower than 3.2". That will put you at max impeller speed at 6500rpm and at 57K at 7000rpm. Its not worth destroying your head unit.
He's not going to destroy his head unit by overspinning it. People over spin the T-trims and S-trims all the time.. Two people I know overspin the tiny s-trim by 10k rpms.. Is it out of it's range? Yes but will it explode no it won't.. Unless he stays at 6500 rpm for extended periods of time which I doubt he will..
Also if you aren't running a intercooler of some sort on your setup which it looks like you are using water meth injection that pulley combo won't be the same for him.. Since he's running a aftercooler there is still some boost loss with his setup, unlike yours.
If he has full exhaust like LT's and a full o/r xpipe he shouldn't need to pulley down anymore than a 3.33'' blower pulley and the 15% O/D that'll be right around 17psi for his setup.. If he isn't running full exhaust or stock logs that number will probably be closer to 19psi which I wouldn't recommend running on 93 octane. But we also need to know what RPM he plans on spinning to. If he wants to go to 7k then that's different than 6500rpm as you mentioned above. :beer: