cam help for twin turbo motor
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cam help for twin turbo motor

  1. #1
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    Default cam help for twin turbo motor

    I am getting ready to swap the cam in my motor but not sure if its a good idea. The cam that is in it is a comp cams blower cam that is a hyd. flat tappet. Part number is 11-400-4. Its specs are intake 226, ext 218 at .050.
    intake lift .525, exhaust .514.
    115 lobe and 111 intake centerline.
    Valve timing at .006
    intake opens 27 btdc closes 69 abdc
    exhaust opens 73 bbdc closes 15 atdc

    The other cam I have is a custom ground cam that I was using for a nitrous motor. Its a solid roller.
    Intake is 242, exhaust 248 at .050
    113 lobe and 113 intake centerline
    valve timing at .050
    intake opens 8 btdc closes 54 abdc
    exhaust opens 57 bbdc closes 11 atdc

    The enigne is a 468 twin turbo with 91mm turbos with 1.23 ar. 990 heads and around 8:1 compression. It is intercooled and was a motor setup for speed skiing. I was told it made 1,000 hp on 12lbs of boost. Never dyno'd the motor though. I am in the process of swapping into my jet boat. Should i swap cams, or keep the cam that is in it and up the boost if I need more power?
    Last edited by 79centurion; 01-17-2012 at 12:22 PM.

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    Blower cam and a turbo cam are 2 different animals. Do you have the flow numbers off the heads?
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    Heads are unported other than cleaned up the opening to match the intake. Here are specs from chevy hi performance


    ValveLift Intake Exhaust Exhaustw/pipe
    050 ****** 32 24 24
    .100 ****** 69 53 53
    .200 ****** 125 101 103
    .300 ****** 183 134 140
    .400 ****** 233 163 176
    .500 ****** 254 180 198
    .600 ****** 292 185 204
    .700 ****** - 186 207
    .800 ****** - - -
    ~E/I ****** 70% 75%

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    I also just read the info on the cam and it is a turbo cam. It was under the blower/turbo cam, but says it a baseline turbo grind helps increase boost

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    Based on those flow numbers and making peak power about 6400 rpm

    700/660
    249/249 @ .050"
    112 Lobe sep
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    Thanks Chris. I think i am going to try to use my nitrous cam then and put 1.8 rockers on the intake side to move the lift to .685 intake, and .654 exhaust. If I had the money i would do another cam, but cant afford to buy another one at this time

    Dan

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    If the smaller cam is already in there you might as well give it a try if it's in good shape.
    Less lift and less abuse on the valve train would be the direction I would go.

    Once you get it running you're probably going to be looking for ways to tame it down, not get more out of it.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology. Tell him that nowadays if you don't have efi, turbos, or an LS you ain't got shit! Lol!!!
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

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    The small cam is in it, and looks new. It only had a few hours of run time on it. I do have 1.8 rockers that I can put on the small cam to help it breath better.

    Dan

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    Quote Originally Posted by 79centurion View Post
    The small cam is in it, and looks new. It only had a few hours of run time on it. I do have 1.8 rockers that I can put on the small cam to help it breath better.

    Dan

    That's what the turbos are for! Haha...it's gonna be a beast, if you don't have exactly what you want leave it alone and run it to see how it does. At least that's what I would do.


    Andrew

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    Food for thought,
    Each one of those 91mm turbo's will flow (a lot) more than the 2 that are on an old school Gale Banks turbo setup.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology. Tell him that nowadays if you don't have efi, turbos, or an LS you ain't got shit! Lol!!!
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

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    I don't want to jack this thread, but I have essentially the same set-up, that is same cam and same heads turning about 6700 rpm, but with the Rajay 301-E10 turbos. Would the recommendation be the same as has already been posted. I am planning to switch to a hydraulic roller cam, any recommendations.

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    Unchained, so you think I should keep the smaller cam in then? It would work for me since its in there. Just didnt want to have to pull it apart and do it all over again. Also the would have to reprogram. Really 1,100-1,200 hp is more than enough.

    Jimsplace, do you know how much hp you have? How much boost, and if in a jet boat what impeller?

  14. #13
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    Quote Originally Posted by 79centurion View Post
    . Also the would have to reprogram. Really 1,100-1,200 hp is more than enough. ?
    It may be a challenge to bypass enough exhaust to run it that low.
    I don't know the specs on the turbine wheel and housing but I would estimate that each of those turbos will be capable of 1200 + HP.
    Did you look up a compressor map ?

    Post up all the info you have on the turbos and maybe we can match a compressor map up to it.
    Measure the turbine exducer also.

    This is a common direction with a turbo program, to try to optimise things to make more power during assembly.
    Then once it's up and running and you see what a monster you created you then want to turn it down.

    If I had it to do over again I would have used an aluminum small block.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology. Tell him that nowadays if you don't have efi, turbos, or an LS you ain't got shit! Lol!!!
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

  15. #14
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    Quote Originally Posted by 79centurion View Post
    Unchained, so you think I should keep the smaller cam in then? It would work for me since its in there. Just didnt want to have to pull it apart and do it all over again. Also the would have to reprogram. Really 1,100-1,200 hp is more than enough.

    Jimsplace, do you know how much hp you have? How much boost, and if in a jet boat what impeller?
    I recently purchased the set-up and don't know the horsepower or the PSI. It is not in a jet.

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