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Higher revving LS motor

This is a discussion on Higher revving LS motor within the Internal Engine forums, part of the LSx Technical Help Section category; Hey guys, I am looking at building a LS motor that has more top end HP than low end torque. ...

  1. #1
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    1986 Turbo 944

    Higher revving LS motor

    Hey guys,

    I am looking at building a LS motor that has more top end HP than low end torque. i have debated with the 383 but the stroker adds too much torque for my transaxle to be comfortable with as a daily driver.

    This is going in my 86 944 Porsche Turbo.

    I want to use my LS6 heads with dual comp valve springs that seat at 148-150lbs, LS1 block, 90mm TB, LS6 intake, and a Granetelli 90 MAF.

    Not sure what else I would need to do besides forged lower internals to make the engine rev up to hopefully 7k and have a power band past 6500.

    I plan it to be a daily driver, highway cruising monster that can hit 180mph+ at top end. That speed gearing means its good for a 70mph cruise rpm and still have tons left to give.

    Any help would be greatly appreciated. I am waiting on this engine build to get the car running again.

  2. #2
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    Quote Originally Posted by cfgioja View Post
    Hey guys,

    I am looking at building a LS motor that has more top end HP than low end torque. i have debated with the 383 but the stroker adds too much torque for my transaxle to be comfortable with as a daily driver.

    This is going in my 86 944 Porsche Turbo.

    I want to use my LS6 heads with dual comp valve springs that seat at 148-150lbs, LS1 block, 90mm TB, LS6 intake, and a Granetelli 90 MAF.

    Not sure what else I would need to do besides forged lower internals to make the engine rev up to hopefully 7k and have a power band past 6500.

    I plan it to be a daily driver, highway cruising monster that can hit 180mph+ at top end. That speed gearing means its good for a 70mph cruise rpm and still have tons left to give.

    Any help would be greatly appreciated. I am waiting on this engine build to get the car running again.
    90mm TB won't work with an LS6 intake.

    I'm not bashing, but why do you need a power band past 6500 with a 180mph top speed. A bolt on LS1 is capable of propelling a 944 to 180+.

  3. #3
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    2000 Trans Am WS6 M6

    My friend I were talking about this a few weeks ago.

    We came to the conclusion that a 5.3L LM7 would would be the best GenIII/IV motor to do this with. It has a low amount of rotating mass. You could bump the compression higher than stock with a good set of heads so you can get the power you want.

    The problem you're going to run into is that the LS6 intake manifold won't flow enough air when you get higher in the RPM range that you'll choke the motor. You'll going to need at least a FAST intake or even better the Edlebrock Pro Flow.

    There are a lot of other factors involved, but this is the extent of my research.

  4. #4
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    1986 Turbo 944

    trying to build the engnine to better suite the weak part of the car, the transaxle. Figured if I can bring power higher into the rpm range it would be better, and I would like to shift closer to new cars if possible so I am not shifting twice as fast.

    sorry the TB is not 90mm it is an LS6 TB.

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    SOM
    1998 T.A.

    A good valvetrain and the best intake you can fit on the motor will help you spin 7k but...... The LS6 IM will start to flatline around 6300-6400. A ported FAST will carry a little higher. You can spin the LS6 past 6400 but there is not much power there so what is the point????

    The cam you choose is also important. Not only will it affect where power is made but will also affect valvetrain control. That is why EPS lobes are in my car. They make good power but they are fat and and have slower jerk than most of the older designed lobes so they are easier to keep out of valve float and give good valvespring life. These lobes are also easier on the valve seats... The Comp LSL lobes on their LSR series of cams are similiar and also a good choice IMO... Good Luck!!!!

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    Quote Originally Posted by SOMbitch View Post
    ...That is why EPS lobes are in my car. They make good power but they are fat and and have slower jerk than most of the older designed lobes so they are easier to keep out of valve float and give good valvespring life. These lobes are also easier on the valve seats... The Comp LSL lobes on their LSR series of cams are similiar and also a good choice IMO... Good Luck!!!!
    Good info! And cfgioja

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    victory red
    2007 zo6

    i hope this helps.. i like my stock cam in 2007 zo6.. good idle/tons of torque/ rev to 7,000 rpm/ did not hit rev limiter ? may be kicks in at 7,200 ? you can look at spec. close to 600 lift ? not sure about duration,but gm did their home work on this cam..covette stock say 427 cubes /505 horses/ forgot torque maybe 480lbs ?

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    1986 Turbo 944

    well just to clarify the situation. I was not talking about just a stock block. Some of the LeMans series race cars are revving in the 9k rpm. I am just hoping for around 7k.

    Here is what I got now that should put me close to that goal.

    Ls1 block, stock bore
    pistons:
    http://www.coasthigh.com/Chevy-LS-5-...ns-p/14217.htm

    rods:
    SCAT 4340 H-beam Connecting Rods - 6.100" Length

    8740 ARP connecting Rod Bolts

    Full Floating Pins

    Assembly is balanced

    Heads:
    LS6 243 heads with 26921 Dual comp cam valve springs

    Cam:
    is a 54-428-11 XFI RPM High Lift
    http://www.compcams.com/Company/CC/c...csid=1091&sb=0

    Rocker Arm upgrade:
    1.72 Ultra Gold
    http://www.compperformancegroupstore...de=GEN3Rockers

    Hi-Tech pushrods:
    http://www.compperformancegroupstore...e=GEN3Pushrods

    Short lift Lifters:
    http://www.compperformancegroupstore...ct_Code=875-16

  9. #9
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    victory red
    2007 zo6

    wow! sounds/looks like a good set up !! maybe i missed it ? what kind of horsepower/ torque, etc.. cant beat these engines ! rkvette

  10. #10
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    1986 Turbo 944

    hoping to keep the 400+ horsepower and 350+ torque. I am aiming ofr what an ls6 has plus some. Since I am also running custom headers

    Do not know the specifics since I am still figuring out the build itself, this is my first true running engine build besides just head gasket and bearing replacements.

  11. #11
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    victory red
    2007 zo6

    i owned a 2002 and- 2004 special edition lemans blue with factory chrome wheels, c/5 zo6's.. they had think 350 cubes and 405 horsepower,.they are quick vettes and had those numbers heads, you are going with.. think only stock factory engine from gm, at that time! had only 350 cubes but over 400 horses.!.they even had a very light exhaust system on those models corvettes.. boy i wish i kept that 2004 zo6 !!. they even had lower gears in the trannys.. rkvette

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