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Thread: 408 stroke restricted

  1. 06-13-2022 #1
    oda521
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    408 stroke restricted

    i?ve built 408 stroker with 10.5:1 compression, 243 heads and tick performance tow max stage 2 cam
    214/224 | .571"/.561" | LSA114+4 are the specs. originally i had a ported throttle body on it with gen 3 intake. now i?ve upgraded to a 4th truck intake with the stock 4 bolt throttle body and torque rush x link. which helped it tremendously. but at WOT my KPA starts at 97 at 2800 rpm and tappers off too 92 at 5200 rpm. when i have the key on engine not running i?m showing 99-100 kpa depending on weather conditions. now my question is. if my throttle body killing me? intake? heads? there?s a restriction somewhere i can only get 10-12 degrees of timing at WOT on 93 octane. this thing falls on its face at WOT. afr commanded 12.5
    this is in a 2007 GMC Sierra 2500 HD Classic. EXT can long bed so she isn?t exactly light lol
    is it worth upgrading to a 102mm throttle body and 4? intake tubing.
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  2. 06-13-2022 #2
    5FDP
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    Yeah I'd be wanting a larger throttle body, something over 90mm for sure with how large that engine is.

    That engine should easily take 20-25 degrees of timing at full throttle.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.
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