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  1. #1

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    Turbo Question, .48a/r or .63a/r

    What would be the best for top end Max speed.
    Can I hit 86+ on the .48a/r exhaust or is too small?
    Thanks,
    Hec


  2. #2
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    Post your EBP (Exhaust Back Pressure ) Readings and I can give you a recommendation.

    Shawn

  3. #3
    t_hoang02's Avatar
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    bigger is always better... I would go with a t3/t04E w/ ball bearings hybrid turbo... this turbo was made for fast spool up and the T04E turbine side is awesome for top end power... its go for up to 500HP...

    http://www.maperformance.com/store/p...roductid=16585

  4. #4
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    Quote Originally Posted by t_hoang02 View Post
    bigger is always better...

    not true. You could get to large that you will enter the surge range on the compressor or If too large a turbine A/R you will not build peak boost.

    But, In general you go larger to move the torque curve up in the power band and go with a smaller A/R to lower it.

    Best to start with the EBP and make a informed decision from that info.

    Shawn

  5. #5
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    Quote Originally Posted by Hecyan View Post
    What would be the best for top end Max speed.
    Can I hit 86+ on the .48a/r exhaust or is too small?
    Thanks,
    Hec
    What happened to you? Haven't seen a post from you in a minute.. I was talking to PBJ about your ski the other day..I couldn't find the post where you explained what pitch and prop you where running to break 80 in salt water.. Please explain so I can pass it on to Jesse..

    Peace,

    Alex

  6. #6

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    How r you alex. Now making changes and going turbo.

    What I did for 80.4 in salt water was tune the 15/19r with the 82.5 ring to 8500-8550. But this was with water temps in the 70's.

    2 weekends ago i hit 78.1mph max. It was too hot to get rpms back. That was with the 83mm ring.
    Take Care,
    Hect

  7. #7

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    Quote Originally Posted by NitroShark View Post
    Post your EBP (Exhaust Back Pressure ) Readings and I can give you a recommendation.
    Ah. . . the data often overlooked. You just got extra points in my book.

  8. #8
    Dave Sharp dav_dman's Avatar
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    Quote Originally Posted by engineermike View Post
    Ah. . . the data often overlooked. You just got extra points in my book.
    Mike, Shawn (nitro) is the Nils of the honda world. He drag races motorcycles. And wins.

  9. #9

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    ???????????/

    how do you measure the back pressure..

  10. #10

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    Quote Originally Posted by JOSE13RT View Post
    how do you measure the back pressure..
    It's not very difficult. On my car, I welded in a 1/8" NPT bung upstream of the turbine. I installed a 6" long pipe nipple and adapted the other end to hose, then a 50 psi pressure gauge. My car has about 34 psi backpressure at 17 psi boost. Our ski's should do better than this since the turbo will likely be more optimally sized.

    Mike

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