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  1. #1

    LS9 Camshaft Specs Wow MINUS 24 degrees overlap 050 lobe

    There is a great LS Engine Cam Comparison by Hot Rod: https://www.hotrod.com/articles/ls-cam-test-comparison/

    Duration 211/230
    Lift .558/.553 w/1.7 rockers, .590/585 w/1.8's
    LSA 122.5, Overlap -24.5
    INT Open -17.0 BTDC, Close 48.0 ABDC
    EXH Open 55.7 BBDC, Close -7.5 ATDC

    Those negative numbers are messing with my brain, but it looks the 10 Degrees Retard is ground into the cam.

    And the LS9 worked good too in HotRods NA comparison engine

  2. #2
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    plumcrazy's Avatar
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    moved the thread as it wasnt about gen1/2
    THE IGNORE FEATURE WORKS, TRY IT...

  3. #3
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    J TNT's Avatar
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    That cam spec is similar to a Gen 3 cam spec ...
    White Mamba ,

  4. #4
    I've never seen the Gen 3 cam specs but the LS9 is radically different from the 708, 710, and the 232/236 cams which are popular.

    In fact, while I am a "muscle car guy," I've never seen a cam with that little overlap or a LSA as large as 122. Even the Crane cams that were offered for the HotRod article to compete were at most 116.

    Since it costs so much time and money to work out cam timings by experimentation, with OEM's now selling 1000 HP (Yenko) cars, I believe researching these OEM cams will produce new knowledge and understanding that can be applied to our cars.

  5. #5
    Enthusiast RyanLS.GEN2's Avatar
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    when comparing the LS9 cam to a viper engine cam remember, v10 and LS are different strokes 3.88-3.996 vs 3.66 LS, the LS cams change alot from rectangle port to cathedral port. vipers change from a oval port to rectangle also, and valve size is also different on many of the engines, and the LS9 is also supercharged, the LS rocker arm is alo a 1.7 ratio stock where alot of the vipers are 1.6 gen1/2 and 1.7 gen3+

    in short it is apples to oranges.

    in size comparisons and head port design you would be better comparing a LS9 cam To a Stage One Supercharger Cam for Gen4 engine, but even thats a bit of a strech

  6. #6
    Did you check out the results of the LS cams (and a Crane trio) they compared in a NA engine? I expected the LS9 lack of overlap to perform poorly but instead it even made more HP. Then the Crane 116 LSA cam with more duration made even more. (I'm going to put the results in a spreadsheet and produce correlation coefficients to see what specs correlate more with increased HP.)

    I've always looked at boost cams from the cam manufacturers catalogs and frankly, they were nothing more than a small tweak of NA cams.

    But 24.5 degrees of negative overlap is a monumental change in valve timing thinking. Obviously, I'm thinking LS9 cam timing for boosted Vipers, especially the screw types.

    NOTE: I contacted a web page of a serious Honda tuner outfit where they discussed "Boosted" cam valve timing. It was all "turbo talk." I emailed them, praised what they disclosed on their site and said it would have been nice if they also covered screw and radial compressors. Interestingly, they said the cam timings are basically the same. I think the key concept is NO overlap - you don't want to "short-circuit" the blower or allow the turbo back pressure to back flow.

    Currently my mind is in Cam Land thinking about an upgrade for my TNT heads/cam/headers 96 GTS with a 224/224 .550 lift 114 LSA cam.
    Last edited by MrCreosote; 11-06-2018 at 12:44 PM.

  7. #7
    What gets me is that even the LSA and LS9 blower cams produce 380 something and 420 something on a 5.3 NA LS engine. The Crane did 440 hp with nothing that exciting.

    440 * 1.25 = 550 hp if you extrapolate a 5.3/8 cyl to a 6.6/10 cyl which is only 405 cu. in. and not 488.

    Assuming the Viper head is not total garbage, one would think there should be significant power gains just with a camshaft. The 5.3 stock cam did 353 hp @ 5200 rpm - the hotter cams pushed HP peak to 6000-6500 rpm.


 

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